JPH06121271A - Video printing method and video printer - Google Patents

Abstract

PURPOSE:To prevent stepwise disturbance in a picture in a tilted direction when a field picture is converted into a frame picture and the converted picture is printed out and to obtain a print of natural reproduction even when picture data of two picture elements in the tilt direction are both 0. CONSTITUTION:The result of adding picture data of upper and lower picture elements with respect to a line to be interpolated is D',x',E' and when the relation of them is D'<x'<E' or D'>x'>E', difference values S1,S2,S3 of picture data of two picture elements in an upper left to lower right direction, in the up-down direction and in an upper right to lower left direction around an interpolation picture element are compared. In the case of S1<S2<S3, xD =(AD+Hb)/2 is obtained and in the case of S1>S2>S3, xD=(CD+FD)/2 is obtained. In other cases and when the relation of D'<x'<E' or D'>x'>E' is not in existence, xD(BD+GD)/2 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video printing method for converting a field image into a frame image for printing.

[0002]

2. Description of the Related Art A video image is composed of a plurality of lines. For example, in a video image picked up by a TV camera, the number of lines on one screen is 525 frame images, which is 1/2 of this, 262. There is a field image consisting of 5 lines. The frame image is superior to the field image in that it has better image quality, but since it requires a large memory capacity to record this, for example, in an electronic still camera, the number of frames that can be taken is reduced. There is.

Therefore, it is preferable that a field image is recorded at the time of shooting and a frame image is output at the time of printing. However, if you convert the field image to a frame image as it is, the space between each line will be opened,
It is necessary to interpolate between them. As this interpolation method,
Conventionally, the average value of the image data of two pixels in the vertical direction of the pixel to be interpolated is generally used as the image data of the interpolated pixel. However, if this interpolation method is applied to a thermal printer that prints a video image on a recording paper 51 with a thermal head 50 in which elongated heating elements 50a are formed in a line shape in the main scanning direction as shown in FIG. When recording an image in which the density level of is gradually changed, the interpolation line 52 is
As in the case of Nos. 3 and 54, an oblique staircase pattern is formed, and this staircase pattern is emphasized to cause image sagging (jaggies).

As a method which can improve this interpolation method to perform more natural interpolation, for example, one described in Japanese Patent Laid-Open No. 63-187785 is known. In this interpolation method, image data of two pixels each in the vertical direction centered on the pixel to be interpolated, in the upper right lower left direction, and in the upper left lower right direction are extracted and the difference values are compared. Then, the average value of the image data of the two pixels in the direction in which the difference value becomes the minimum is used as the image data of the interpolated pixel.

[0005]

By the way, in FIG. 9 showing each image data by taking out 3 × 3 pixels centered on the pixel to be interpolated, the image data of two diagonal pixels are both “ Since it is "0", the image data P of the pixel to be interpolated becomes 0 according to the above interpolation method. However, the image data of the upper and lower pixels is “10
Since it is "0" and "95", it is unnatural to set the image data P of the pixels sandwiched between them to "0". Rather, it is natural to take the average value of the image data “100” and “95” of the upper and lower pixels to be “97.5”. As described above, the above-described interpolation method sometimes causes an unnatural result, and improvement has been desired.

According to the present invention, it is possible to prevent the sagging of a stepwise image in an oblique direction, avoid the unnatural reproduction as described above, and convert a field image into a more natural frame image for printing. It is intended to provide a video printing method.

[0007]

In order to solve the above problems, a video printing method according to a first aspect of the present invention has a pixel to be interpolated from a line to be interpolated and two lines above and below the line to be interpolated. Image data of 3 pixels on the interpolation line, and the upper and lower 2
It is assumed that the image data of each pixel is an addition value, and when the image data of three pixels on the interpolation line increases or decreases in the line direction, the first pixel centered on the interpolation pixel is used. The absolute value of the difference between the image data of two pixels in the diagonal direction is S1, the absolute value of the difference between the image data of two pixels in the vertical direction centered on the interpolated pixel is S2, and the second diagonal When the absolute value of the difference between the image data of two pixels in the direction is S3, S1 <S2 <S3 or S
When the conditional expression 1>S2> S3 is satisfied, an oblique direction with a small absolute value of the difference is selected, and the average value of the image data of the two pixels in the selected oblique direction is set as the image data of the interpolated pixel. In other cases, the average value of the image data of the two pixels above and below the interpolation pixel is used as the image data of the interpolation pixel.

A video printer according to a second aspect of the present invention includes an analog video input terminal for inputting a reproduced color image signal of a field image and an image for performing a required correction by dividing the input color image signal into a digital component signal. A signal processing circuit, an interpolation operation unit for converting the processed digital component signal from field image data to frame image data, and a thermal head for driving the component signal of the frame image interpolated by the interpolation operation unit. A signal conversion circuit for generating a thermal head drive signal for each color and a thermal head are included, and the interpolation calculation unit includes data for one field before and after interpolation processing or one before interpolation processing for each component signal system.
It has a pair of field memories each capable of storing data for one field, and at least one interpolation operation unit of the component signal system inputs a first field memory having a pre-interpolation data input terminal and its output. It has a second field memory that stores and outputs the data after the interpolation processing, and the output of the first field memory is connected to the input terminal of the signal conversion circuit of the next stage through the synthesizing circuit and also in parallel. The unprocessed data, which is connected to the interpolation direction determination circuit and the interpolation calculation circuit, is input to the interpolation direction determination circuit, the correction direction is determined by the interpolation direction determination circuit, and the output of the direction determination is input to the interpolation calculation circuit. , A predetermined calculation is performed according to the direction determination output from the data for one field before the interpolation process output from the first memory, and the frame after the interpolation process is performed. Field data once stored as field data in the second field memory, the second field memory connected to the synthesizing circuit is added to the first field memory output, and the interpolated component data for one frame is input to the signal conversion circuit. It is composed of an interpolation calculation processing circuit connected to a terminal.

[0009]

As a result, for example, when the image data of two pixels in the vertical direction of the interpolated pixel is not "0", but the image data of the two pixels in the diagonal direction are both "0". The interpolated pixel image data is "0".
It avoids unnatural corrections such as
The field image is converted into a natural and high quality frame image and printed.

[0010]

FIG. 2 shows a 3 × 3 pixel centered on a pixel x to be interpolated from a line (scanning line) to be interpolated and two lines above and below the line to be interpolated. , The image data of the pixels A, B, and C on the upper line (for example, luminance data or density data) are A _D , B _D , and C _D , respectively.
And the image data of the pixels F, G, H on the lower line are F _D , G _D , and H _D , respectively. From this, D '= A _D + F _D x' = B _D + G _D E '= C _D + H _D S1 = | A _D −H _D | S2 = | B _D −G _D | S3 = | C _D −F _D | To calculate. Note that, for convenience, the pixels on the left and right of the interpolated pixel x are
Let pixels D and E.

As shown in FIG. 1, first, D ', x',
Compare E '. D '<x'<E'orD'> x '>
If E ′, then pixels A, B, C, D, x, E,
It can be considered that the brightness or density of the region consisting of F, G, and H is gradually changing in the scanning direction. In this case, when the image data x _D of the interpolated pixel x is interpolated by the image data B _D and G _D of the pixels B and G in the vertical direction, only a staircase-like image sag occurs in the diagonal direction. A,
Image data A _D of H, H _D, or image C, the image data C _D of F, interpolating those close correlation of F _D performed.

By comparing S1, S2 and S3, S1 <S2 <
If S3, the image data A _D , H of the pixels A, H
The average value of _D , (A _D + H _D ) / 2, is the image data x _D of the interpolated pixel x. When S1>S2> S3, the average value of the image data C _D and F _D of the images C and F, (C
The _D + F _D) / 2 and the image data x _D of the interpolation pixel x.
If neither of these is true, or if D '<x'<E'orD'> x '>E', then pixels A, B, C,
Since the luminance or the density of the area consisting of D, x, E, F, G, and H does not change gradually, the interpolation pixel is interpolated by the image data B _D and G _D of the pixels B and G in the vertical direction of the interpolation pixel x. Interpolate the image data x _D of x. That is, x _D = (B _D + G _D ) /
Set to 2.

Next, a thermal printer for carrying out the recording method shown in FIG. 1 will be described with reference to FIGS. 3 and 4. For example, a video floppy shot by an electronic still camera is set in a still video player. The video signal of the field image reproduced here is input to the Y / C separation circuit 11 and separated into a luminance signal Y and a color signal C. This color signal C is supplied to the decoder 12 to generate a color difference signal R-
The luminance signal Y and the color difference signals R-Y and B-Y are converted into Y and B-Y, and are quantized by the A / D converter 13 and converted into, for example, a digital signal having 64 gradations. The digitized luminance data Y'and color difference data R'-
Y'and B'-Y 'are input to the color masking circuit 14 and subjected to color correction.

Luminance data Y ', color difference data R'-Y',
When B'-Y 'is input to the interpolation calculation unit 15, it is shown in FIG.
As described above, the field memories 16a, 16c,
16e is once recorded. Next, the brightness data Y'is
Interpolation direction determination circuit read from the field memory 16a
17, the interpolation direction, that is, the vertical direction, as shown in FIG.
Direction, upper right lower left direction and upper left lower right direction
The smaller direction is selected. Then, the interpolation calculation circuit 18
For example, x_D= (A_D+ H_D) / 2 is not calculated
Luminance data x of this interpolated pixel x_DIs a field memo
16b is recorded. After this, the field memory 16
luminance data Y ', x from a, 16b at the same time _DRead out
Then, the contour correction is performed as the brightness data for one screen of the frame image.
It is input to the circuit 21.

The luminance data Y'input to the contour correction circuit 21 is contour-emphasized by, for example, a spatial filter represented by the following equation (1), and then input to the matrix circuit 22. This expression (1) shows the brightness value of the spatial filter called the second-order differential calculation (Laplacian), where the position of 3 × 3 pixels is (i, j). That is, the brightness value of the pixel whose contour is to be corrected is multiplied by "4", the brightness value of each of the left, right, upper and lower pixels is respectively multiplied by "-1", and these are added to obtain the contour emphasis component. It is added to the luminance value of.

Color difference data R'of the line to be interpolated
As -Y ', the same data input to the field memory 16c is input to the field memory 16d. Then, the color difference data R'-Y 'is read from the field memories 16c and 16d at the same time, and this is input to the matrix circuit 22 as the color difference data R'-Y' for one frame image. Similarly, the same color difference data B'-Y 'as in the field memory 16e is input to the field memory 16f, and the field memories 16e, 16
The color difference data B′-Y ′ is read from f as the color difference data B′-Y ′ for one screen of the frame image and input to the matrix circuit 22.

Luminance data Y ', color difference data R'-Y',
B′−Y ′ is converted into R ′,
It is converted into three primary color signals of G'and B '. The luminance data Y ', the color difference data R'-Y', B'-Y 'and R',
As is well known, the relationship with the G ′ and B ′ signals is expressed by the following equation. Y '= 0.3R' + 0.59G '+ 0.11B'R'-Y'=0.7R'-0.59G'-0.11B'B'-Y'=-0.3R'-0.59G"+0.89B"

The R ', G', and B'signals are .gamma.-corrected by the .gamma.-correction circuit 23 in accordance with the color-developing characteristics of the thermal recording paper 24, and converted into M, Y, and C signals representing the density. This M,
The thermal head 25 is sequentially driven by the Y and C signals. First, the thermal head 25 is driven by the Y signal to thermally record the yellow thermosensitive coloring layer of the thermosensitive recording paper 24, and then an ultraviolet ray of a predetermined wavelength is irradiated by a dedicated ultraviolet lamp to perform optical fixing. Similarly, the magenta thermosensitive coloring layer of the thermosensitive recording paper 24 is thermally recorded by the M signal and is optically fixed. Finally, the cyan thermosensitive coloring layer of the thermosensitive recording paper 24 is thermally recorded by the C signal. This thermal head 2
As is well known, a large number of heating elements 5 are arranged in a line in the main scanning direction.

As shown in FIG. 5, the thermosensitive recording paper 24 has a structure in which a cyan thermosensitive coloring layer 32, a magenta thermosensitive coloring layer 33, and a yellow thermosensitive coloring layer are provided on a support 31 made of an opaque coated paper or a plastic film. 34, protective layer 35
Are sequentially layered. Each of these thermosensitive coloring layers 32 to 3
4 is layered from the surface in the order of thermal recording. The cyan thermosensitive coloring layer 32 contains an electron-donating dye precursor and an electron-accepting compound as main components, and develops cyan when heated.

As the magenta thermosensitive coloring layer 33, a diazonium salt compound having a maximum absorption wavelength of about 365 nm,
It contains a coupler which thermally reacts with this to develop a magenta color. This magenta thermosensitive coloring layer 33 has a thickness of 365 nm after the magenta image is thermally recorded by the thermal head 25.
When irradiated with ultraviolet rays in the vicinity, the diazonium salt compound is photolyzed and the coloring ability is lost.

The yellow thermosensitive coloring layer 34 contains a diazonium salt compound having a maximum absorption wavelength of about 420 nm and a coupler which thermally reacts with this compound to develop yellow. When this yellow thermosensitive coloring layer 34 is irradiated with near ultraviolet rays in the vicinity of 420 nm, the yellow thermosensitive coloring layer 34 is photo-fixed and loses its coloring ability.
In FIG. 3, the ultraviolet lamp for fixing is not shown. Also, the luminance signal Y and the color signal C of the field image
If the signal is already separated, the luminance signal Y and the color signal C are directly input to the decoder 12 from the S terminal.

The thermal printers shown in FIGS. 6 and 7 are the same as those of the above embodiment in that the luminance signal Y and the color difference signal R of the video signal are used.
-Y, BY was interpolated, R, G,
The B signal is interpolated. After color correction is performed by the color masking circuit 14, R, G, B
The signals are respectively stored in the field memory 36 of the interpolation calculation unit 40.
a, 36c, 36e. Then, the interpolation direction determination circuit 37 determines the interpolation direction for the G signal read from the field memory 36a, and based on this interpolation direction, the interpolation calculation circuits 38a, 38b, and 38c perform R, G, and R of the lines to be interpolated. The B signal is calculated and input to the field memories 36b, 36d and 36f. Thereafter, the G signal is read from the field memories 36a and 36b, the R signal is read from the field memories 36c and 36d, and the B signal is read from the field memories 36e and 36f, respectively, and the field image is converted into a frame image. The R, G, B signals of this frame image are input to the contour correction circuit 41, subjected to the contour enhancement as described above, and then transmitted to the matrix circuit 22. Hereinafter, since it is similar to the above-mentioned embodiment, the description thereof will be omitted.

The above-described embodiments have been described with respect to a thermal printer for recording an image on a thermosensitive recording paper on which a thermosensitive coloring layer is laminated, but the present invention is not limited to this, and for example, sublimation using an ink sheet. A thermal printer of a thermal transfer recording system or an inkjet printer may be used. Also, I explained the line printer,
The present invention can also be applied to a serial printer.
Further, although the interpolation processing is performed on the luminance data, the interpolation processing may be performed on the density data.

[0024]

As described in detail above, according to the video printing method and the video printer of the present invention, 3 × 3 is used.
When the image data of the three pixels on the line to be interpolated using the reference pixel of No. 1 increases or decreases in the line direction, the interpolated pixels are located in the upper left lower right direction, the vertical direction, and the upper right lower left direction. The difference values of the image data of two pixels are compared, and when the difference values are gradually changing in the scanning direction, the diagonal direction having the smaller difference value is selected, and the image data of the two pixels in the selected diagonal direction are selected. The average value is used as the image data of the interpolated pixel, and in other cases, the average value of the image data of the two pixels above and below the interpolated pixel is used as the image data of the interpolated pixel. It is possible to improve bleeding, and it is possible to obtain a print having natural reproducibility without causing unnaturalness even when image data of diagonal pixels is “0”.

[Brief description of drawings]

FIG. 1 is a flowchart showing an interpolation method according to the present invention.

FIG. 2 is an explanatory diagram showing 3 × 3 reference pixels.

FIG. 3 is a block diagram of a thermal printer that implements the interpolation method shown in FIG.

FIG. 4 is a circuit diagram showing an internal structure of a correction calculation unit.

FIG. 5 is an explanatory diagram showing the structure of the thermal recording paper.

FIG. 6 is a block diagram of another thermal printer that implements the interpolation method shown in FIG.

7 is a circuit diagram showing an internal structure of an interpolation calculation unit of the thermal printer shown in FIG.

FIG. 8 is an explanatory diagram showing a print example according to a conventional interpolation method.

FIG. 9 is an explanatory diagram showing another conventional interpolation method.

[Explanation of symbols]

 15, 40 Interpolation calculation unit 16a to 16f, 36a to 36f Field memory 17, 37 Interpolation direction determination circuit 18, 38a, 38b, 38c Interpolation calculation circuit 24 Thermal recording paper 25 Thermal head

Claims (2)

[Claims] 1. A field image is converted into a frame image by storing image data of the field image in a memory and performing an interpolation process to increase the number of lines in printing.
In the video printing method for printing this frame image, a 3 × 3 pixel centered on the pixel to be interpolated is extracted from the line to be interpolated and the two lines above and below this line It is assumed that the image data of the pixel of is the addition value of the image data of two pixels above and below, and the image data of three pixels on the interpolation line increases or decreases in the line direction. Let S1 be the absolute value of the difference between the image data of two pixels in the first diagonal direction centered on the interpolation pixel, and the difference between the image data of two pixels in the vertical direction centered on the interpolation pixel. Let S2 be the absolute value of S2 and S3 be the absolute value of the difference between the image data of the two pixels in the second diagonal direction, S1 <S2 <S
3 or the conditional expression of S1>S2> S3 is satisfied, an oblique direction having a small absolute value of the difference is selected, and the average value of the image data of the two pixels in the selected oblique direction is set as the image data of the interpolated pixel. In other cases, the video printing method is characterized in that the average value of the image data of two pixels in the vertical direction of the interpolation pixel is used as the image data of the interpolation pixel. 2. An analog video input terminal for inputting a color video signal of a reproduced field image, a video signal processing circuit for dividing the input color video signal into digital component signals and performing a necessary correction, and this processing. An interpolating operation unit for converting the digital image component signal obtained from the field image data into the frame image data, and a thermal head driving signal for each color for driving the thermal head from the component signal of the frame image interpolated by the interpolating operation unit And a thermal head, and the interpolation calculation unit can store data for one field before and after interpolation processing or data for one field before interpolation processing for each component signal system. A pair of field memories and at least a component The interpolation calculation unit of one system of the signal system has a first field memory having a pre-interpolation data input terminal and a second field memory for storing the output data after the interpolation processing for inputting the output. The output of the first field memory is connected to the signal conversion circuit input terminal of the next stage via the synthesis circuit, and is also connected in parallel to the interpolation direction determination circuit and the interpolation calculation circuit, and is input to the interpolation direction determination circuit. The correction direction of the previous data is determined by the interpolation direction determination circuit, and the output of which the direction is determined is input to the interpolation calculation circuit, and the direction is determined from the data for one field before the interpolation processing output from the first memory. A predetermined operation is performed according to the discriminant output, the interpolated field data is temporarily stored in the second field memory, and the second field memory connected to the synthesizing circuit. There video printer, characterized in that it consists of interpolation calculation processing circuit is added to the first field memory output is connected to one frame of the component data interpolated into the signal conversion circuit input terminals.