JP5898735B2 - Information processing apparatus and print medium - Google Patents

Description

  The present invention relates to a dot pattern that is superimposed and printed on halftone dot printing, on which a dot pattern that can be read by being discriminated as a halftone dot by an optical reading means is printed, and information for reading a dot pattern using the print medium The present invention relates to a processing method and an information processing apparatus.

  The inventor of the present application has invented many techniques for optically reading the dot pattern of such a medium in which the dot pattern is printed superimposed on the image and outputting information.

  Patent Document 1 discloses an invention in which a dot pattern and a map are superimposed and printed, and the dot pattern on the map is read to output information corresponding to the coordinates on the map.

  Patent Document 2 discloses an invention in which a dot pattern and a keyboard pattern for a personal computer are superimposed and printed, and a dot pattern on a keyboard key is read to input instructions corresponding to the key to the personal computer. Has been.

  Patent Document 3 discloses a method of reading only a dot pattern when an area in which an image and a dot pattern are superimposed and printed is read by an optical reading unit. According to Patent Document 3, in order to read only a dot pattern, an image is printed with a non-carbon ink, and the dot pattern is printed with a transparent or translucent infrared absorbing ink or carbon black. Carbon black (black) absorbs infrared rays, irradiates the infrared rays with an optical reading means, images only the infrared rays reflected from the medium surface, and reads the dot pattern. Therefore, in the case of color printing, five colors are printed.

  On the other hand, according to Patent Document 4, in order to reduce the printing cost, black ink is expressed in a pseudo manner (so-called composite black) with non-carbon CMY ink instead of non-carbon K (black) ink, and the same ink as in the past. Color printing can be performed in four colors.

JP 2007-79993 A Japanese Patent No. 4042065 WO2004 / 029871 WO2007 / 021249

  According to Patent Document 3, non-carbon CMYK ink for images and invisible infrared absorbing ink (stealth ink) for dot patterns, that is, five colors of ink are required for printing, and in particular, stealth ink is expensive. There was a point.

  According to Patent Document 4, an image is expressed only with non-carbon CMY ink using a composite black in which a black color is simulated with CMY ink. However, since composite black is a dark dark brown, it is a vivid black. There was a problem that could not be expressed.

  In view of the above problems, an object of the present invention is to make it possible to express vivid colors without increasing the number of colors and to suppress the printing cost of a printing medium on which a dot pattern is printed. As a result, it is possible to superimpose and print a graphic and a dot pattern with one color, which has been impossible in the past, without using inks having different frequency characteristics.

  In order to solve the above problems, the present invention employs the following means.

  (1) The print medium of the present invention can be read by the optical reading means, and the read bitmap image data can be decoded into predetermined information by the image analysis processing means. The grid is defined according to a predetermined rule to define the predetermined information. A printing medium in which a dot pattern in which dots are arranged and characters, patterns, photographs, etc. printed using halftone dots are superimposed and printed, and a predetermined method based on brightness information recorded in the bitmap image data Are detected so that the image analysis processing means can determine whether the dots are grid dots or halftone dots constituting the dot pattern. And

  Here, the brightness information indicates the brightness of all colors, black is the lowest brightness, and by printing the dot pattern in black, it is compared with the brightness of the color expressed by halftone dots. Grid dots can be identified. If the difference is slight, the color portion may be printed with the lightness of the color portion increased, or may be determined by correcting so as to increase the lightness of the color portion read by the image analysis processing means. As a result, only the grid dots can be detected and the dot pattern can be recognized regardless of the optical reading means using the frequency characteristics and the ink used.

  (2) Further, the image analysis processing means calculates the number of pixels constituting dots detected by a predetermined method from the bitmap image data formed by pixels, and the pixels are compared with a preset threshold value. When determining whether the dot is the grid dot or the halftone dot depending on the number, it is determined that the dot is a grid dot when the number of pixels constituting the dot is larger than the threshold, and the number of pixels constituting the dot Is determined to be a halftone dot when it is smaller than the threshold value.

  As a result, even if the color brightness of the overlapped portion where each halftone dot of CMY overlaps decreases and it becomes difficult to discriminate based on the brightness of the grid dots and the halftone dots, the number of pixels constituting the overlapped portion will be less than the threshold value. If printing is performed, discrimination from grid dots becomes possible. Of course, if CMYK is used for color printing and the brightness of the K dot and the grid dot are about the same, it can be discriminated by the number of pixels constituting both.

  (3) Further, the grid dots and the halftone dots are printed using the same ink.

  Thereby, even when grid dots and halftone dots are printed using the same kind of ink, only the grid dots can be detected and the dot pattern can be recognized.

  (4) Further, the grid dots and the halftone dots are printed using ink that absorbs infrared rays in a predetermined wavelength region.

  As a result, when the dot pattern is recognized using an optical reading means that captures only infrared rays, halftone printing is performed with CMYK (carbon black that absorbs infrared rays) used in normal printing, and ink that absorbs infrared rays in the same manner as K ink. Even when grid dots are printed, it can be discriminated by the number of pixels constituting both.

  (5) Further, the halftone dots that are printed adjacent to each other are set as predetermined dots so that the image analysis processing means can detect them as individual dots so that the halftone dots are not connected to each other from the bitmap image data. It is printed with a halftone dot density.

  This makes it possible to distinguish grid dots by printing halftone dots with a predetermined halftone density in consideration of printing accuracy so that the number of pixels constituting the connected halftone dots does not exceed the threshold and grid dots cannot be distinguished. Make it possible. In addition, even if a part of halftone dots is connected due to variations in printing, since the brightness of the connecting portion is slightly higher, the connection can be disconnected.

(6) Further, the grid dots are rectangular or elliptical arcs, and when the length in the short side direction is L (inch) and the number of halftone dot printing screen lines is D (lpi), the halftone dot shape is circular. In the case where the predetermined halftone dot density X (%) is less than 25πL ² × D ² and the halftone dot shape is square, the predetermined halftone dot density X (%) is 50 L ² × D. It is printed with less than ² .

  As a result, if there is a slight variation in printing, it can be discriminated by the number of pixels constituting both. However, when there are many variations in printing, it is preferable to print halftone dots by reducing the predetermined halftone dot density by about 10%.

  (7) The information processing method according to the present invention includes a dot pattern in which grid dots are arranged according to a predetermined rule to define predetermined information, and a character, a picture, a photograph, or the like printed using a halftone dot. An information processing method of reading an overprinted print medium with an optical reading unit, and decoding the read bitmap image data into the predetermined information with an image analysis processing unit, wherein the image analysis processing unit includes the bitmap Detecting a dot by a predetermined method from lightness information recorded in image data, determining whether the dot is a grid dot or a halftone dot constituting the dot pattern, and decoding the predetermined information And

  This makes it possible to recognize only grid dots regardless of the type of optical reading means and the reading method.

  (8) Further, the image analysis processing means calculates the number of pixels constituting dots detected by a predetermined method from the bitmap image data formed by pixels, and the number of pixels with respect to a preset threshold value is calculated. When determining whether the dot is the grid dot or the halftone dot depending on the size, it is determined that the dot is a halftone dot when the number of pixels constituting the dot is smaller than the threshold, and the number of pixels constituting the dot is When it is larger than the threshold value, it is determined that the dot is a grid dot and is decoded into predetermined information.

  (9) Further, the image analysis processing means includes a threshold value table or a predetermined calculation formula, detects a pixel value indicating brightness information excluding the dots in a predetermined area of the read bitmap image data, and detects the threshold value. A grid dot is determined by obtaining a threshold value corresponding to the pixel value from a table or a predetermined calculation formula.

  As a result, in a state where the optical reading means is tilted or slightly away from the medium surface, the shooting area is widened.As a result, the grid dots and halftone dots are reduced, and the number of pixels constituting the grid dots is reduced. Grid dots can be determined by using a threshold value table corresponding to lightness or a threshold value obtained from a predetermined calculation formula even if the threshold value of a predetermined number of pixels falls below the threshold value. . This is because the lightness in the lightness measurement area in the center of the image data developed in the image memory decreases when the optical reading means is tilted or slightly separated from the medium surface. Then, the threshold value of the number of pixels may be dynamically reduced to determine whether the dot is a grid dot or a halftone dot.

  (10) Further, the image analysis processing means includes a first threshold value table or a predetermined calculation formula for determining the halftone dots and the grid dots, and a grid read by the optical reading means excluding at least halftone dots. A second threshold value table for determining dots or a predetermined calculation formula is provided, and either one is selected by a predetermined method to determine a threshold value corresponding to the pixel value to determine a grid dot.

  As a result, two different threshold tables or predetermined values can be used for both discrimination of grid dots printed as small as possible so as to be inconspicuous on a normal grid dot print medium and discrimination of halftone dots on a medium printed with relatively large grid dots. The grid dots can be identified by using different formulas. As one specific example, an optical reading unit that reads only grid dots with frequency characteristics (optical characteristics), both normal grid dot print media and print media printed with the same ink as the grid dots, It can be read and decoded into predetermined information.

  (11) Further, the printing medium is characterized in that the grid dots and the halftone dots are printed using the same ink.

  (12) Further, the printing medium is printed using an ink in which the grid dots and the halftone dots absorb infrared rays in a predetermined wavelength region, and the optical reading means includes at least a filter that blocks visible light, and at least An infrared irradiation unit in the predetermined wavelength region is provided, and the optical reading unit reads the print medium printed with ink that absorbs infrared rays in the predetermined wavelength region.

  (13) Further, the image analysis processing unit reads the print medium on which the halftone dots are printed at a predetermined halftone density by the optical reading unit so that the halftone dots printed adjacent to each other are not connected. In this case, each dot is detected from the read bitmap image data so as not to be connected to each other, and it is determined whether the dot is the grid dot or the halftone dot, and is decoded into predetermined information.

(14) Furthermore, the grid dots are rectangular or elliptical arcs, and when the length in the short side direction is L (inch) and the number of halftone dot printing screen lines is D (lpi), the grid dots are rectangular. When the halftone dot shape is circular, the predetermined halftone dot density X (%) is less than 25πL ² × D ² , the grid dots are rectangular, and the halftone dot shape is square When the predetermined halftone dot density X (%) is less than 50 L ² × D ² , the grid dots are elliptical arcs, and the halftone dot shape is circular, the predetermined halftone dot density X (%) is 25π. in less than ^{2 L 2 × D 2/4} , the grid dots are elliptical arc, when the net-point shape is square, the predetermined halftone dot density X (%) is less than 50πL ² × D ^2/4 It is printed.

  (15) Further, the image analysis processing means detects the pixel as a dot when the pixel value indicating the brightness information recorded in the bitmap image data formed by the pixel is equal to or less than a predetermined threshold value, and It is characterized by determining whether a dot is a grid dot or the halftone dot and decoding predetermined information.

  (16) Further, the image analysis processing means includes a first pixel arranged in a horizontal direction and a second pixel separated by a predetermined number of pixels in each pixel of each row of the bitmap image data formed by pixels. A pixel value indicating brightness information recorded in each is detected, and when the absolute value of the difference between the two pixel values is equal to or greater than a predetermined threshold, a small pixel value is detected as a dot, and the dot is a grid dot Or the halftone dot, and when it is a grid dot, predetermined information is decoded.

  (17) Further, the predetermined threshold is a pixel value indicating brightness information excluding the dots in a predetermined area in the center of the bitmap image data, and a threshold table or a predetermined calculation formula corresponding to the pixel value is detected. It is more required.

  As a result, individual differences in performance occur in the optical reading means, and even if the brightness information of the read bitmap image data varies, it is possible to determine the optimum threshold value and determine the grid dots. Also, the brightness of the read bitmap image data decreases when the optical reading means is not completely in contact with the medium surface or when the optical reading means is tilted with respect to the print medium surface. However, it is possible to determine grid dots by obtaining an optimum threshold value correspondingly.

  (18) Further, the predetermined threshold value is a threshold value table corresponding to the pixel value detected in each row of the bitmap image data by detecting a pixel value indicating brightness information excluding the dot in a predetermined region at the center of each row. Alternatively, it is obtained for each row by a predetermined calculation formula.

  As a result, when the optical reading unit is tilted with respect to the print medium surface, the brightness of the read bitmap image data decreases in the reverse direction from the side where the optical reading unit is tilted forward, but the bitmap image data By obtaining an optimum threshold value in each row, grid dots located in each row can be more accurately determined.

  (19) The information processing apparatus according to the present invention includes a dot pattern in which grid dots are arranged according to a predetermined rule to define predetermined information, and a character, a pattern, a photograph, etc. printed using a halftone dot. An information processing apparatus that reads an overprinted print medium by an optical reading unit, and that decodes a dot pattern constituted by grid dots from the read bitmap image data into the predetermined information by an image analysis processing unit, The image analysis processing means detects a dot by a predetermined method from the brightness information recorded in the bitmap image data, determines whether the dot is a grid dot or a halftone dot constituting a dot pattern, When it is a grid dot, it decodes to predetermined information, It is characterized by the above-mentioned.

  (20) Further, the image analysis processing means calculates the number of pixels constituting dots detected by a predetermined method from the bitmap image data formed by pixels, and the number of pixels with respect to a preset threshold value is calculated. When determining whether the dot is the grid dot or the halftone dot depending on the size, it is determined that the dot is a halftone dot when the number of pixels constituting the dot is smaller than the threshold, and the number of pixels constituting the dot is When it is larger than the threshold value, it is determined that the dot is a grid dot and is decoded into predetermined information.

  (21) Further, the printing medium is printed using an ink in which the grid dots and the halftone dots absorb infrared rays in a predetermined wavelength region, and the optical reading means includes at least a filter that blocks visible light, and at least An infrared irradiation means in the predetermined wavelength region is provided.

  Thereby, since CMY used in normal printing does not absorb infrared rays, only halftone dots printed with K ink that absorbs infrared rays and grid dots printed with ink that absorbs infrared rays are imaged with an optical reading means, A grid dot can be discriminated by brightness or the number of pixels constituting both. That is, the determination is made with only two colors of the halftone dot and the grid printed with K ink, or when the K ink is used for printing the grid, the determination is made with only one color.

  (22) Further, the dot pattern includes a step of arranging a plurality of reference dots continuously in a line according to a predetermined rule, and a first line comprising a straight line, a broken line, and / or a curve connecting the plurality of reference dots. Providing at least one second virtual reference line comprising a straight line and / or a curve defined at a predetermined position from the reference dot and / or the first virtual reference line A step, a step of providing a plurality of virtual reference points at predetermined positions on the second virtual reference line, and an end point expressed by a vector with the virtual reference point as a starting point, and a distance and direction from the virtual reference point A stream dot pattern arranged in accordance with the step of arranging information dots in which XY coordinate values and / or code values are defined is formed by arranging one line or a plurality of lines. The

  According to this, by forming a plurality of stream dot patterns with a fixed reference point interval, XY coordinate values are defined on the print medium without gaps, and trajectory information can be generated. Furthermore, when characters, staffs, maps, figures, etc. are printed on a print medium, and the user scans or touches the line segment with a scanner pen, a stream dot pattern is formed only along that line segment. , Can arrange the dot pattern reasonably. In addition, when a dot pattern in which XY coordinates are defined is formed as a two-dimensional code (used as an index), it is not restricted by the shape of the rectangular area, and is matched to the information area visually formed on the medium surface. In addition, it is possible to form a dot pattern by repeating a set of constant information in a free shape.

  (23) Further, the stream dot may further include a reference for defining a second virtual reference line and / or for defining a direction of the dot pattern and one XY coordinate value and / or code value. The reference dot is provided at a predetermined position.

  According to this, by setting a new reference point, it is possible to easily define the direction of the stream dot pattern and a set of constant information without using information dots, thereby suppressing unnecessary information reduction. It is done. Furthermore, the position of the virtual reference point that is the starting point of the information dot can be accurately indicated by the arrangement of the new reference point.

  According to the present invention, it is possible to detect a dot pattern by detecting only grid dots regardless of optical reading means utilizing frequency characteristics and ink used.

  Therefore, even when grid dots and halftone dots are printed using the same kind of ink, only the grid dots can be detected and the dot pattern can be recognized. This makes it possible to recognize the dot pattern by superimposing the dot pattern on the graphic even in a single color printing medium such as monochrome printing.

It is an enlarged view for explaining a state in which halftone dots and grid dots are superimposed and printed with ink having the same frequency characteristics. It is an enlarged view showing a state in which halftone dots and grid dots are superimposed and printed with one color ink. It is an enlarged view which shows the state which printed the halftone dot and the grid dot with the ink which has a different frequency characteristic. It is the figure which expressed the halftone dot and the grid dot with the bitmap image. It is a figure explaining the method of determining the magnitude | size of a halftone dot. It is a figure explaining the method of discriminating a halftone dot and a grid dot. It is a figure explaining the other method explaining the method of discriminating a halftone dot and a grid dot. It is a figure explaining the method to discriminate | determine whether the halftone dot or the grid dot is printed. It is a figure explaining an optical reading means. FIG. 3 is an enlarged view of a captured image of a print medium according to the present invention. It is a figure (1) explaining the stream dot pattern which is an example of the dot pattern used for this invention. It is a figure (2) explaining the stream dot pattern which is an example of the dot pattern used for this invention. It is a figure (3) explaining the stream dot pattern which is an example of the dot pattern used for this invention. It is a figure (4) explaining the stream dot pattern which is an example of the dot pattern used for this invention. It is a figure (5) explaining the stream dot pattern which is an example of the dot pattern used for this invention. It is a figure (6) explaining the stream dot pattern which is an example of the dot pattern used for this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  1 to 3 are enlarged views illustrating a state in which halftone dots and grid dots (dots used in a dot pattern) are superimposed and printed.

  FIG. 1 illustrates a state where halftone dots and dot patterns are superimposed and printed, and is an example of reading in the visible light region using an optical reading unit. (A) shows normal halftone dot printing, (b) shows a dot pattern, and (c) shows a state in which a graphic and a dot pattern are superimposed and printed.

  Here, normal graphic printing means normal halftone dot printing of characters, photographs, illustrations, and the like. A dot pattern is a kind of two-dimensional code, and is an automatic recognition technique for inputting and outputting various information and programs. Specifically, it is disclosed in Japanese Patent No. 3706385, Japanese Patent No. 3858051, Japanese Patent No. 3771252, Japanese Patent Application No. 2009-165163, and the like. Of course, any dot pattern may be used.

  Normal graphic printing is performed using three colors of C (cyan), M (magenta), and Y (yellow) (FIG. 1A) or four colors of C, M, Y, and K (black). On the other hand, the dot pattern is printed using K ink (FIG. 5B). Then, as shown in FIG. 5C, normal graphics and dot patterns are superimposed and printed. As a result, when the user touches the print medium with a dedicated scanner (optical reading means) for reading the dot pattern, information such as sound / image corresponding to the contents of graphic printing is transferred to the information device ( Output from a personal computer, PDA, or the like.

  In this embodiment, the ink used for these graphic printing and dot pattern printing discriminates the brightness difference between the halftone dot and the dot pattern in the visible light region. It does not matter. That is, although not shown, a predetermined brightness is set as a threshold value, and the dot portion of the bitmap image data read by the optical reading means is determined as a grid dot if it is larger than the threshold value, and determined as a halftone dot if it is smaller than the threshold value. . Thereby, it is possible to detect the dot pattern by detecting only the grid dots regardless of the optical reading means using the frequency characteristics (optical characteristics) and the ink used. Here, at the position where the composite black in which C, M, and Y are mixed is represented, not only the difference in brightness, but also the halftone dots read by the optical reading means and recorded in the bitmap image data as shown in FIG. And the number of pixels constituting the grid dot are compared, and if it is equal to or greater than the predetermined number of pixels, it is necessary to determine that the dot is a grid dot. Of course, when four colors C, M, Y, and K (black) are used for normal graphic printing, determination is made with a predetermined number of pixels at the position where K (black) is printed. In this figure, the halftone dots are represented by squares, but the present invention is not limited to this, and it is needless to say that grid dots can be discriminated similarly in halftone dot printing having other shapes such as a circle.

  FIG. 2 shows a state in which a halftone dot and a dot pattern are printed with one color ink.

  In the figure, both halftone dots and grid dots are printed with M ink. In the present invention, even in such a case, the halftone dots read by the optical reading means and recorded in the bitmap image data are compared with the number of pixels constituting the grid dots. It is possible to determine that the dot is a grid dot. However, it is necessary to print by limiting the density of the halftone dots and / or the number of screen lines of the halftone dots so that the size of the halftone dots is necessarily smaller than the grid. Of course, in consideration of printing accuracy, paper quality, and ink characteristics such as dot gain during printing, the dot size must be determined so that the dot size is always smaller than the grid dot in the printed result. .

  As described above, according to the present invention, it is possible to distinguish between halftone dots and grid dots even when printing is performed in one color. This makes it possible to print a dot pattern on a document, text, or graphic that is printed only in one color, such as a single color printing of a newspaper, a test question, a questionnaire, or the like.

  The ink for printing in one color is not limited to M ink, but may be printed with C ink, Y ink, and K ink.

  FIG. 3 shows a state in which a graphic and a dot pattern are printed with inks having different frequency characteristics. In the figure, the graphic is printed with four colors of C, M, Y, and K, and the dot pattern is printed with one color of K ink. Then, ink that reflects or transmits infrared light is used for C, M, and Y printing, and ink that absorbs infrared light or carbon black is used for K printing. In this case, the optical reading means reads only the halftone dots and gridts printed in the infrared region and printed with K, and is recorded in the bitmap image data. Pixel values (lightness) constituting the halftone dots and grid dots Are approximately the same, and the number of pixels constituting each dot is compared. If the number of pixels is equal to or greater than a predetermined number, it can be determined that the dot is a grid dot. The optical reading means has a structure in which infrared rays are irradiated onto the medium surface and only the infrared rays in the reflected light are read by a visible light blocking filter (infrared transmission filter).

  Thus, in the present invention, inks having different frequency characteristics depending on the color of the ink may be used.

  4A and 4B are diagrams in which halftone dots and grid dots are represented by bitmap images, where FIG. 4A shows grid dots and FIG. 4B shows halftone dots.

  The graphic or dot pattern read by the optical reading means is developed as a bitmap image on the image memory. That is, it is expressed by being divided into many fine points (pixels) in a grid pattern.

  On the image memory, halftone dots and grid dots are imaged brightly at locations where they are not printed. The image analysis processing means inside the scanner detects a dark imaged portion from the bitmap image data. Then, the number of pixels constituting them is calculated, and whether the dot is a grid dot or a halftone dot is determined according to the number of pixels. As a criterion for determination, a threshold value for the number of pixels is set. When the pixel number is larger than the threshold value, it is determined as a grid dot, and when the pixel number is smaller than the threshold value, it is determined as a halftone dot. It should be noted that when a halftone dot and / or a grid dot is detected whether it is bright or dark, the determination is made based on a predetermined lightness threshold. Note that grid dots may be set above the threshold, halftone dots below the threshold, grid dots above the threshold, and halftone below the threshold.

  For example, when the threshold is set to 12, since it is 15 pixels in FIG. 4A, it is determined to be a grid dot. In FIG. 6B, since it is 8 pixels, it is determined to be a halftone dot.

  Here, in a state where the optical reading means is tilted or slightly away from the medium surface, the shooting area is widened.As a result, the grid dots and the halftone dots are reduced, and the number of pixels constituting the grid dots is reduced. There are cases where the threshold value of the preset number of pixels falls below and is determined as a halftone dot. In order to avoid this, when the optical reading means is inclined or slightly separated from the medium surface, the brightness of the image data developed in the image memory is lowered, so that the pixel according to the brightness at that time. The threshold value of the number may be lowered dynamically. If the central area of the image data is a brightness measurement area, an average value of pixel values excluding dots is obtained in the brightness measurement area, and is calculated from this average value as shown in FIG.

Is a threshold value for the number of pixels. If it is less than the threshold value T, it is determined to be a halftone dot, and if it is greater than or equal to the threshold value, it is determined to be a grid dot. In this calculation formula, when the average value of pixel values is λ1 or less and λ2 or more, the threshold number of pixels is a constant value N1 and N2, and from λ1 to λ2, the threshold number of pixels is

It becomes. For example, a 4mm square on the surface of a print medium is captured and the image data developed in the image memory has a resolution of about 144 x 144, brightness information is 8 bits (0 to 255), grid dot diameter is 0.1 mm or more, and dot printing If the screen line count is equivalent to 175 lpi and the dot density is less than 20%, the values of λ1 = 60, N1 = 8, λ2 = 180, and N2 = 12 may be set. Needless to say, this value varies depending on the printing method, ink type, dot gain, paper quality, optical reading means performance, and the like.

  By the way, in an ordinary grid dot printing medium, only grid dots are printed, or only grid dots are optically read by using inks having different frequency characteristics (optical characteristics) for grid dot printing and halftone dot printing. Usually, the predetermined information is read by reading. In this case, the grid dots are made as small as possible so as not to stand out, or invisible ink is used. Here, in order to eliminate noise such as scattering of grid dot ink during printing and missing / damage of the image sensor of the optical reading means, the threshold value of the number of pixels must be set similarly. However, when the image data has a resolution of about 144 × 144, the number of pixels constituting the noise is as small as 1 to 2 (increases when the resolution of the read image data is large), and the printed grid is as small as possible. A small value is also set for the threshold for discriminating dots. Therefore, a threshold value for a different number of pixels must be set for a normal grid dot print medium and a print medium that is discriminated based on the number of pixels that form halftone dots and grid dots.

  Therefore, as shown in FIG. 4D, the second threshold value calculation formula for a normal grid dot printing medium is used.

If the grid dot is read using either the first threshold calculation formula T or the second threshold calculation formula T ′ and the predetermined information cannot be decoded, the other threshold calculation formula is used. The read image data is analyzed again. If the analysis is successful, the threshold calculation formula is subsequently used. Thereafter, if the analysis cannot be performed again, the read image data may be analyzed again using the other threshold calculation formula. For example, a 4mm square on the surface of a print medium is captured and the image data developed in the image memory has a resolution of about 144 x 144, brightness information is 8 bits (0 to 255), grid dot diameter is 0.1 mm or more, and dot printing If the screen line number is equivalent to 175 lpi and the dot density is less than 20%, λ1 = 60, N1 = 8, λ2 = 180, N2 = 12, λ1 ′ = 80, N1 ′ = 2, λ2 ′ = 160, N2 A value of ‘= 4’ may be set. Needless to say, this value varies depending on the printing method, ink type, dot gain, paper quality, optical reading means performance, and the like.

  FIG. 5 is a diagram for explaining a method for determining the size of a halftone dot.

  In the present invention, the size of the halftone dot is determined in relation to the size of the grid dot. The grid dots are a rectangle as shown in FIG. 5A or an elliptical arc as shown in FIG. Most of them are square or circular, and in particular, they are often defined as squares for convenience in data creation and reduction of data capacity.

  On the other hand, circular halftone dots are arranged as shown in FIG. 3C, and square halftone dots are arranged as shown in FIG. The dotted line shows the case where the halftone dot density is 70% in FIG. 10C and the halftone dot density is 50% in FIG. Thus, if the density of halftone dots is 70% or 50% or more, the halftone dots are in contact with each other on the data. As a result, the number of pixels constituting the halftone dot increases, and the image analysis processing means erroneously determines that the halftone dot is a grid dot. Further, in a normal offset, a rotary press, and various printers, even if the halftone dot density is 50% for a circular halftone dot and 40% for a square halftone dot, they may be connected as shown in FIG. In this way, when dots are printed, halftone dots are connected due to factors such as dot gain, ink type, printing method, paper quality, etc., in which ink permeates into the periphery and the printing area expands. Although not shown in the figure, if the dot is less than about 40% for a circular halftone dot and less than about 30% for a square dot, printing can be performed without being connected. However, in order to suppress the halftone dot density to less than 30 to 40%, an image that is slightly black may not be obtained. Needless to say, the printing accuracy varies depending on the printing method, ink type, dot gain, paper quality, optical reading means performance, and the like. Here, depending on the printing accuracy, even if the halftone dot density is suppressed to less than 30% to 40%, some of the halftone dots may be connected, so that the image analysis processing means can make the determination. Since the brightness of this connection part is brighter than the central part of the halftone dots, the connection can be disconnected by comparison. When the printing variation is large, if the halftone dot density is less than about 2 to 30%, the halftone dot connection is completely eliminated, and the grid can be determined more accurately.

Next, the maximum printing halftone density when the grid dots are set to a predetermined size is determined. The short side of the rectangular and elliptical arc grid dots is L inches. Also, if the number of printed screen lines of a halftone dot is D lpi, and the halftone dot is circular, the diameter R inch of one halftone dot having a halftone dot density of X% is assumed to be r inch. ,
πr ² / (1 / D) = X / 100,
Therefore

It becomes.

Here, to print so that L> R, the dot density X is
X <25πL ² × D ²
It becomes. Here, since the shape of the grid dot is generally a square, when comparing the side length L of the square of the grid and the diameter R of the circular halftone dot, the area of the square is definitely larger even if there is no difference. Even if there is a slight variation in printing, there is a difference in the number of pixels constituting the dot, and the grid dot can be identified. If the grid dot shape is circular, the dot density X needs to be reduced by π / 4,
^{X <25π 2 L 2 × D} 2/4
It becomes.

When the halftone dot is a square, the diagonal length K inch of one halftone dot having a halftone dot density of X% is k inch.
k ² / (1 / D) = X / 100
And
Therefore

It becomes.

Here, to print so that L> K, the dot density X is
X <50L ² × D ²
It becomes.

Here, since the shape of the grid dot is generally a square, when the side length L of the grid square is compared with the diagonal length K of the square halftone dot, the area is surely the square of the grid even if there is no difference. Even if there is a slight variation in printing, the difference in the number of pixels constituting the dot occurs and the grid dot can be identified. If the grid dot shape is circular, the dot density X needs to be reduced by π / 4,
^{X <50πL 2 × D 2/} 4
It becomes.

  As a result, if there is a slight variation in printing, it can be discriminated by the number of pixels constituting both. However, if there are many variations in printing, the halftone dot size in the printed result is a grid, taking into account the fact that printing accuracy decreases due to the printing method, ink type, dot gain, paper quality, optical reading means performance, etc. Since the size of the halftone dot must be determined with a margin so as to be surely smaller than the dot, it is preferable to print the halftone dot with the predetermined halftone dot density reduced by about 10%. Of course, by increasing the number of halftone dot printing screens as described above, the size of the halftone dots can be reduced even with the same halftone dot density, and the grid can be determined more accurately.

  FIG. 6 is a diagram for explaining a method for discriminating between grid dots and halftone dots.

  As described above, an image photographed by the optical reading unit is formed by a set of pixels as a bitmap image on the image memory.

  FIG. 4A shows image data developed in the image memory of the optical reading means. The image analysis processing means extracts a certain number of pixels in a certain region at the center of the image data. This certain number is determined by the relationship between the number of pixels constituting the grid dots and the number of pixels in a certain region in the center of the image data. A certain area in the center of the image data may be defined by a number of pixels that is four times or more the maximum number of pixels constituting a grid dot, and the number of pixels equal to or less than 1/4 may be set to a certain number. In addition, it is not necessary to stick to this calculation method if grid dots and / or halftone dots do not exist in the extracted fixed number.

  FIG. 4B is an enlarged view of the extracted area. The image analysis processing means calculates the brightness of each pixel. Then, as the lightness measurement region, a predetermined number (for example, 10) of pixels B (1) to B (10) are extracted in descending order of lightness, and the lightness average value of each lightness measurement region is extracted.

Ask for.

  As shown in the figure (c), it is calculated from this average value.

Is determined to be a halftone dot if it is equal to or greater than the threshold T, and a grid dot if it is less than the threshold.

  When obtaining the threshold value, as shown in FIG. 7, for each line of image data, a fixed number of pixels that are not dots (grid dots and / or halftone dots) in the center area (brightness measurement range) of each line are extracted. May be. When the resolution of the bitmap image is m × n, pixels in the center region are extracted from the first calculation scanning line to the mth calculation scanning line. Then, the threshold value is obtained by the same method as in FIG. 6 based on the average value of the brightness of the pixels extracted for each line. Here, the center area (width) of each line of image data is determined by the number of pixels that is four times or more the maximum width of the pixels constituting the grid dots, and the brightness measurement range is set. It may be a certain number. In addition, it is not necessary to stick to this calculation method if grid dots and / or halftone dots do not exist in the extracted fixed number.

  Due to the tilt of the scanner, the image data includes a darkly imaged area and a brightly imaged area. Therefore, by obtaining a threshold value for each line, it becomes possible to more accurately discriminate halftone dots and grid dots. In addition, in order to increase the accuracy of discrimination, image data is divided, and the threshold value for each divided area is calculated from the average value of the brightness of pixels in which no grid dots and / or halftone dots exist in the central area of the divided area. Then, it may be detected and determined. When grid dots and / or halftone dots are detected on a line, the threshold values on the line change discontinuously. Therefore, the threshold values are calculated by interpolation so that these threshold values change continuously on the line. If detected, the accuracy of discrimination of grid dots can be further increased.

  FIG. 8 is a diagram for explaining a method of discriminating between an area where grid dots or halftone dots are printed and an area where neither is printed (blank area).

  The image analysis processing means calculates the brightness for each line of the image data.

  FIG. 5A shows a specific example of image data. Thus, the brightness varies depending on the pixel. FIG. 4B shows the brightness for each pixel in a bar graph.

  The image analysis means calculates a difference in brightness between an arbitrary pixel i (first pixel) among pixels in the horizontal direction and a pixel i + n (second pixel) that is separated from i by a predetermined number n. Find the absolute value of. If the absolute value of the difference is greater than or equal to a predetermined threshold, the pixel with the smaller brightness is determined to be a dot (either a grid dot and / or a halftone dot). Even if the absolute value of the brightness difference between an arbitrary pixel i (first pixel) and a pixel i + n (second pixel) that is a predetermined number away from i is equal to or smaller than a predetermined threshold value, If it is determined that one pixel is a dot, it is reserved that the pixel is a dot, and the second pixel is also determined to be a dot. That is, the first pixel and the second pixel are pixels that form the same dot. Furthermore, in order to improve accuracy, the second pixel is reserved as a dot candidate, and the absolute value of the brightness difference is equal to or greater than a predetermined threshold value when compared with the second pixel. If so, it may be formally determined that the first pixel is a dot. Here, when the absolute value of the brightness difference is equal to or smaller than the predetermined threshold value, the second pixel is also reserved as a dot candidate, and the determination may be continued. When the determination is continued and it is officially determined that the first pixel is a dot, the previous dot candidates may be officially determined as dots. If the absolute value of the brightness of the pixel is used to determine whether or not the dot is a printed area, when the optical reading means is tilted, a dark portion is generated and all the dots are determined. Further, if the determination is made based on the difference value between adjacent pixels, fine noise (electronic light / dark or slight light / dark depending on the printing environment) is recognized, making it difficult to accurately determine the dots. Therefore, if the difference is detected at a certain distance as in the present embodiment, a considerable difference occurs in the brightness between the two, and the grid dot can be determined. However, the constant distance n is preferably smaller than the number of pixels between adjacent dots.

  FIG. 9 is a diagram showing the structure of the scanner (optical reading means).

  The scanner incorporates an IR-LED that is an infrared irradiation unit that irradiates the medium surface, a visible light blocking filter that cuts a visible light length component of the reflected light, a C-MOS sensor that is an imaging device, and a lens. And a diffuser capable of diffusing infrared rays applied to the medium surface from the infrared irradiation means and uniformly irradiating the medium surface. The scanner photographs the reflected light of the irradiation light irradiated on the medium. Since the dot pattern is printed with ink having the characteristic of absorbing infrared rays, only the grid dot portion is photographed black in the image captured by the C-MOS sensor. Note that the visible light blocking filter may be provided below the C-MOS sensor or near the photographing port.

  A medium that uses an ink that reflects or transmits infrared rays when ink that absorbs infrared rays is used for grid dots and halftone dots by determining the grid dots based on the number of pixels that make up the dots. It is possible to discriminate grid dots simply by comparing the halftone dots using the ink that blocks the reflected light from the surface and absorbs infrared rays and the grid dots. In addition, when ink that absorbs infrared rays is not used for printing halftone dots and grid dots, an IR-LED that is an infrared irradiation unit and a visible light blocking filter that cuts a visible light length component of the reflected light are not necessary.

  10A and 10B are enlarged views (photographs) of a captured image of the print medium according to the present invention. On the image memory read by the optical reading means, image data as shown in FIGS. This image was taken of a 4 mm diameter area on a printed media surface printed with a grid dot diameter of 0.1 mm or more, a dot printing screen line number equivalent to 175 lpi and a dot density of 20%, and a resolution of 288 x 288 In the image memory, brightness information is recorded as 8-bit (0 to 255) image data.

FIG. 6A shows image data when the optical reading means is read vertically with respect to the print medium surface, and FIG. 10B shows image data when the optical reading means is read with an inclination of about 40 degrees. It can be seen that the size of the halftone dots and grid dots in FIG. 6B are clearly smaller than those in FIG. By using the calculation formula of FIG. 4C, even if there is no difference between the size of some of the halftone dots in FIG. 4A and the size of some of the grid dots in FIG. By using different threshold values for (a) and (b), it is possible to distinguish between halftone dots and grid dots.
<Description of dot pattern Stream dots>
Next, an example of a method for forming a stream dot, which is an example of a dot pattern used in the present invention, will be described with reference to FIGS.
A stream dot is a dot pattern disclosed in Japanese Patent Application No. 2009-165163.

  11 and 12 sequentially show an example of a process for forming a stream dot pattern.

  The dot pattern according to the present invention is different from the conventional dot pattern. First, in step 1, corresponding to the visible information on the surface of the medium, the reference dot 1 is continuously arranged in a line at a position where information is input / output. Place multiple.

  In FIG. 11A, the reference dots 1 are arranged in a curved shape, but the arrangement of the reference dots 1 is not limited to this, and is composed of a plurality of line segments interwoven with straight lines and curves. Various modifications can be made to form the dot pattern in a shape that matches the area where information is input and output, such as a polygonal line.

  Further, the reference dot 1 may be arranged on an actual line that is visibly formed on the medium surface, or the reference dot 1 may be arranged according to a predetermined rule along the actual line. The real line here is a concept with respect to a virtual line, and includes all the lines that actually exist. For example, a solid line, a broken line, a dotted line, a straight line, a curved line, and the like can be mentioned. In the present invention, regardless of the medium on which the line is formed (for example, a display of a video display device) or the substance that forms the line (for example, ink) Absent. In addition, the dot pattern may be unevenness such as printing, display display, or a hole or groove on a metal or plastic.

  In addition, it is desirable to arrange the reference dots at equal intervals from the viewpoint of improving reading accuracy, but the reference dots are not limited to this, and a plurality of intervals are mixed to define a set of constant information of the dot pattern, It is also possible to define both a set of constant information of a dot pattern and a direction of the dot pattern by arrangement intervals of three different reference dots in the set of fixed information.

  Next, as step 2, a first virtual reference line 2 that connects the reference dots 4 arranged in a line is provided. In FIG. 11B, the first virtual reference line 6 is provided by a curved line. However, the first virtual reference line 2 is not limited to this, and the reference virtual dots 1 arranged in a curved line are not limited thereto. The straight first virtual reference line 2 may be provided, or the curved first virtual reference line 2 may be provided for the reference dots 1 arranged in a straight line. That is, the second virtual reference line 3, the virtual reference point 4, and the information dot 5 in Step 3 to Step 5 which will be described later are arranged according to the positions where the reference dots are connected to each other. One virtual reference line 102 can be freely defined.

  As shown in FIG. 13, the first virtual reference line 102 in the case of a curve is preferably a Bezier curve.

  That is, first, the reference dots 1 on the first virtual reference line 2 are P0 and P3, and P1 and P2 are given control points. Next, points P4, P5, and P6 are obtained by dividing the three line segments P0-P1, P1-P2, and P2-P3 obtained by connecting the control points in order at a one-to-one ratio. Then, points P7 and P8 are obtained by dividing the two line segments P4-P5 and P5-P6 obtained by connecting these points in order at a one-to-one ratio.

  Finally, a point P9 that further divides the line segment connecting the two points, P7-P8, at a ratio of 1: 1 is obtained, and this point becomes a point on the Bezier curve.

  By repeating this procedure, a Bezier curve having control points P0, P1, P2, and P3 is obtained.

  The first virtual reference line 2 may be provided using various algorithms such as a spline curve obtained by using a spline function, an nth order polynomial, an elliptic arc, and the like, not limited to a Bezier curve.

  Also, in the second virtual reference line 3, it is possible to define a curve using this method as in the first virtual reference line 2.

  Next, as step 3, a second virtual reference line 3 defined at a predetermined position from the reference dots 1 and / or the first virtual reference line 2 arranged in a line is provided. In FIG. 11C, the second virtual reference line 3 is adjacent to the reference dot 1 adjacent to a predetermined position on the vertical line with respect to the tangent line of the first virtual reference line 2 at the midpoint between the adjacent reference dots 1. However, the second virtual reference line 3 is not limited to this, and a virtual reference point is provided in accordance with an area in which information is input / output by a dot pattern as will be described later. In addition, it can be defined by various methods.

  Further, the second virtual reference line 3 may be provided only on one side with respect to the first virtual reference line 2 to define the direction of the dot pattern, or may be provided on both sides to increase the amount of information. .

  Next, as step 4, a plurality of virtual reference points 4 are provided at predetermined positions on the second virtual reference line 7. In FIG. 12A, the virtual reference point 4 is an isosceles triangle with the intersection of the second virtual reference lines 3, that is, a straight line connecting adjacent reference dots 1 as the base and the second virtual reference line 3 as the opposite side. However, the position of the virtual reference point 4 is not limited to this, and is provided at the midpoint of the second virtual reference line 3 or instead of the second virtual reference line 3. Various modifications such as provision on the dot 1 are possible.

In step 5, the information dot 5 is arranged at the end point expressed by a vector with the virtual reference point 4 as the start point. In FIG. 12B, one information dot 5 is arranged for one virtual reference point 4 so that the vector direction from the virtual reference point 4 is eight directions and the distance from the virtual reference point 4 is equal. However, the arrangement of the information dots 5 is not limited to this, and the information dots 5 are arranged on the virtual reference point 4, the vector direction is set to 16 directions, or two are arranged for one virtual reference point 4. It is possible to arrange a plurality of elements in any direction and in any length.
FIG. 14 is an enlarged view showing an example of dot display information dots and bit display of data defined therein.
The information dot 5 is a dot for recognizing various information. This information dot 5 is arranged at the end point represented by a vector with the virtual reference point 6 as the start point. For example, as shown in FIG. 12, the information dot 5 is rotated by 45 degrees in the clockwise direction because a dot 0.1 mm away from the virtual reference point 4 has a direction and a length expressed by a vector. These are arranged in 8 directions to represent 3 bits.

  In the illustrated example, 3 bits are expressed by arranging in 8 directions, but the present invention is not limited to this, and 4 bits can be expressed by arranging in 16 directions. Of course, it can be arranged in length.

Further, in FIG. 12B, the information dot 5 is arranged at the end position of the virtual reference point 4 with the virtual reference point 4 as the starting point. However, the dot is not limited to this and is not limited to this. Information may be defined depending on whether or not is arranged. For example, information can be defined as “1” if a dot is arranged on a virtual reference point, and “0” if no dot is arranged.
FIG. 15 shows an example of the information dot and the bit display of the data defined therein, and shows another form.

  Further, regarding the information dot 5, if two types of short (upper part in FIG. 15) and long (lower part in FIG. 15) are used from the virtual reference point 4 derived from the reference dot 1, and the vector direction is 8 directions, then 4 bits. Can be expressed. At this time, it is desirable that the longer one is about 25-30% of the distance between the adjacent virtual reference points 5, and the shorter one is about 15-20%. However, it is desirable that the center interval between the long and short information dots 3 is longer than the diameter of these dots.

The information dot 3 is preferably one dot in consideration of its appearance. However, if the appearance is ignored and the amount of information is to be increased, a large amount of information can be obtained by assigning 1 bit to each vector and expressing the information dot 3 with a plurality of dots. For example, the vector of concentric eight directions, an information dot 3 defined from the reference dots 4 can represent information of 2 ^8, and 2 ⁶⁴ in chunks of the information dot eight constant information 1.

  As described above, the stream dot pattern according to the present invention is continuous with a line including a curve unlike the reference dot formed in a two-dimensional lattice pattern in the conventional dot pattern proposed by the present inventor. Are formed based on the reference dots arranged in this manner.

  FIG. 16 is a diagram illustrating an example of a state where stream dot patterns are arranged in the vertical direction.

  In the figure, in addition to the reference dots and information dots, key dots and side dots are arranged. Key dots are dots arranged at both ends of a set of fixed information. This key dot is a representative point of the dot pattern 1 for one region representing a group of information dots. The side dots are dots arranged on the positive and negative extension lines of the shift of the key dot 2.

  In FIG. 6B, reference dots and stream dot patterns are arranged at equal intervals. As described above, by forming a plurality of stream dot patterns having a constant reference point interval, the XY coordinate values are defined without a gap. However, the stream dot pattern according to the present invention is not limited to this, and the interval between the dot patterns may be arbitrarily set as shown in FIG. Also, the interval between the reference dots can be set arbitrarily.

  As a result, the dot pattern in which the XY coordinates are defined is formed in the information area visually formed on the medium surface without being restricted by the shape of the rectangular area when used as a two-dimensional code (used as an index). It is possible to form a dot pattern by repeating a set of constant information in a combined free shape.

  Note that the virtual reference line and the virtual reference point according to the present invention are not actually printed and formed on the surface of the medium, but only when the dot pattern is arranged on the image memory of the computer or when the dot pattern is read. Is set virtually.

By using this stream dot pattern, it is possible to form a dot pattern on a curved surface body such as a globe, a three-dimensional structure such as a human body model, a three-dimensional map, etc., and the present invention is not limited to a planar map or picture book. It is possible to use the input / output device according to the above.

  The present invention can be used for any printed matter. Regardless of the optical reading means using the frequency characteristics and the ink used, only the grid dots are detected, and the dot pattern can be recognized.

  Therefore, even when grid dots and halftone dots are printed using the same kind of ink, only the grid dots can be detected and the dot pattern can be recognized. This makes it possible to recognize the dot pattern by superimposing the dot pattern on the graphic even in a single color printing medium such as monochrome printing. As a result, it is possible to perform printing with reduced costs. Furthermore, as an optical reading means, it is possible to discriminate and read a dot pattern imaged by a consumer product such as a mobile phone, a digital camera, or a web camera.

1 reference dot 2 first virtual reference line 3 second virtual reference line 4 virtual reference point 5 information dot

Claims (4)

Optical reading hand stage reading the print medium a dot pattern grid dots are arranged, and / or print data is printed using halftone dots, but is printed in accordance with a predetermined rule to define a predetermined information the dot pattern and / or dot read by the storage means for recording a bit map image data to be formed in pixels,
An image analysis unit you analysis the bitmap image data,
An information processing apparatus comprising:
The image analysis processing means includes
Of the pixels forming the bitmap image data, recorded in each of a first pixel which is an arbitrary pixel and a second pixel which is separated from the first pixel by a predetermined number of pixels in the horizontal direction. detecting the brightness, it calculates the difference between each of the brightness, that the absolute value of said difference is out detection as a dot having a small the pixel value when it is above a predetermined threshold value,
Information processing device. The image analysis processing means includes
It has been determined in advance that the first pixel is the dot,
If the absolute value of the brightness difference between the first pixel and the second pixel is less than or equal to a predetermined threshold,
Determining that the second pixel is also the dot;
The information processing apparatus according to claim 1. The image analysis processing means includes
Further, the brightness of a third pixel separated from the second pixel by a predetermined number of pixels in the horizontal direction is detected,
Calculating the brightness difference between the second pixel and the third pixel;
If the absolute value of the difference is below a predetermined threshold,
The calculation of the lightness difference is repeated until the lightness difference between the nth pixel and the (n + 1) th pixel horizontally separated from the nth pixel by a predetermined number of pixels is equal to or greater than a predetermined threshold. From pixel to nth pixel are determined to be dots,
The information processing apparatus according to claim 2.   In order to define predetermined information, a dot pattern in which grid dots are arranged according to a predetermined rule and / or print data printed using halftone dots are read by an optical reading unit that reads a printed print medium. Recording the dot pattern and / or halftone dots in the storage means as bitmap image data formed of pixels;
  Analyzing the bitmap image data by image analysis processing means;
An information processing program for executing
  The image analysis processing means includes
  Of the pixels forming the bitmap image data, recorded in each of a first pixel which is an arbitrary pixel and a second pixel which is separated from the first pixel by a predetermined number of pixels in the horizontal direction. Detecting brightness, calculating a difference between each brightness, and detecting a small pixel value as a dot when the absolute value of the difference is equal to or greater than a predetermined threshold;
Information processing program.