JPH04188950A - Picture processor - Google Patents

Abstract

PURPOSE:To appropriately implement a counter measure to various kinds of inputted picture signals, and to output an optimal processed picture by selecting a converting method according to the maximum value of an inputted analog signal. CONSTITUTION:Plural luminance and density conversion tables, in addition to the program of a control procedure, are stored in a read-only memory(ROM) 108. For example, a high level mode at the time of the high level of an outputted signal from a reading part 101, and a low level mode at the time of the low level of the outputted signal from the reading part 101, are prepared as the mode of the luminance and density conversion. Then, the optimal luminance and density table is selected by the maximum value (maximum potential value) of an analog picture output from the CCD line sensor part of the reading part 101. Thus, it is possible to appropriately deal with the various kinds of the inputted picture signals, and to output the optimal processed picture.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an image processing device that converts an analog image signal expressed by luminance information into a digital image signal expressed by corresponding density information, and includes, for example, a plurality of tables for converting luminance information into density information. The present invention relates to an image processing apparatus including means for selecting the table.

[Conventional technology]

Conventionally, image information from an original with gradation has been extracted using CC, for example.
When reading and quantizing with an image sensor such as a D sensor, luminance data that is the output of the image sensor is converted into density data. Some of these systems are known to have a plurality of tables for this conversion within one system, and any table can be selected depending on the type of document and the like.

[Problem to be solved by the invention]

However, the selection can be made, for example, by the machine user using the operation keyboard as needed.
” or “thin”, etc., and the table corresponding to the input is uniquely selected. Therefore, it is very troublesome, and if the user makes a setting error, the read information will be of poor image quality. Further, the photoelectric conversion characteristics unique to the image sensor are not taken into account at all, and the photoelectric conversion characteristics are not corrected, so that linearity of density cannot be ensured. Typically, a fluorescent lamp is used as a light source for reading documents. In general, the amount of light from a fluorescent lamp changes greatly depending on temperature, and the amount of light from a fluorescent lamp can differ several times between the maximum and minimum times. At this time, the output of the CCD is, for example, the fourth
The values are shown in the figure. FIG. 4(a) shows the output of the CCD when the amount of light from the fluorescent lamp is maximum, and FIG. 4(b) shows the output from the COD when the amount of light from the fluorescent lamp is the minimum. In both cases, V represents the maximum value in the l line (white area), and ■ represents the output of the black area. As shown in Figure 4, the output V2 in the white part falls in proportion to the intensity of the light amount, whereas the output V2 in the black part is grounded (GND) due to the influence of stray light even when the light intensity decreases. It is a predetermined level range that does not fall to the same level and does not change much. Normally, when converting CCD output from A/D, ■, ~G
Since the conversion is performed in proportion to ND, for example, V, = 64
．． If GND=O, in the case of Figure 4(a), V will be at the 4th level, but in the case of Figure 4(b), vs will be at the 10th level. If the same table is used when performing luminance-density conversion in FIG. 4(b), the density of "black" will be lower in FIG. 4(b). Even if the same document is read in FIG. 4(b) as in FIG. 4(a), the overall density will be lower (and the resulting image will be "thinner").

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above-mentioned problems, and includes the following configuration as a means for solving the above-mentioned problems. That is, in an image processing apparatus that converts an analog image signal expressed by luminance information into a digital image signal expressed by corresponding density information, an input means for inputting an input analog image signal expressed by luminance information; The analog-to-digital conversion means converts an input analog image signal into a corresponding digital image signal, and the random access memory converts the output signal from the analog-to-digital conversion means into corresponding density data using at least two methods. The apparatus includes a conversion means capable of converting, a processing means for quantizing the density data converted by the conversion means, and a selection means for selecting a conversion method of the conversion means based on the maximum value of the input analog signal from the input means. Further, a plurality of data conversion tables are further provided, and the selection means selects one from the plurality of data conversion tables and writes the selected data conversion table into a random access memory which is the conversion means, and the selection means Density conversion processing is performed using the selected data conversion table. [Operation] In the above configuration, by selecting the conversion method of the conversion means according to the maximum value of the input analog signal from the input means, it is possible to appropriately correspond to input image signals of various specifications and output an optimal processed image. .

【Example】

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, and this embodiment shows an example in which the present invention is applied to a facsimile machine. In FIG. 1, reference numeral 101 is a reading unit that scans a document with a CCD (solid-state image sensor) line sensor (document reading sensor 200 shown in FIG. 2, which will be described later) and reads image information from the document. Outputs an analog image signal represented by a signal. 102 is an image processing unit that performs image processing on the input image signal from the reading unit 101, and the image processing unit 102 converts the signal read by the CCD (solid-state image sensor) line sensor of the reading unit 101 into a digital density signal. Quantization processing is performed to binary data of white/black. Note that the image processing unit 102 will be explained in detail later. Reference numeral 103 denotes a recording unit for recording images, and the recording unit 103 is constituted by a printer capable of permanently visible display, such as a thermal transfer printer, a laser beam printer, or an inkjet printer, which is normally used in facsimile machines. 10
Reference numeral 4 denotes an operation unit for operating the facsimile machine of this embodiment, which includes a plurality of key manual switches, a key constant distortion circuit,
It consists of a display device such as a liquid crystal display for displaying various information and a display drive circuit. Reference numeral 105 denotes an encoding/decoding unit that performs encoding processing of converted binary data sent from the image processing unit 102 and decoding processing of received data. 106 is a CPU stored in a read-only memory (ROM) 108 via the system bus 100, which controls the entire system of this embodiment according to the control procedure shown in FIG. 4, which will be described later. 107 is a random access memory (RAM). ) and is used as a work area for the image processing unit 102 and CPU 106. 108 is a ROM in which, in addition to the above-mentioned program, a plurality of brightness/density conversion tables shown in FIG. 3 are stored.
In this embodiment, the brightness/density conversion mode is "high level" when the output signal from the reading unit lot is at a high level.
mode and a "low level" mode when the output signal from the reading unit 101 is at a low level, and two density data shown in FIG. 3 that are output in response to the input luminance signal level are stored. There is. In this example, for the sake of simplicity, only two brightness/density conversion modes are shown; however, the number of modes is not limited to these two, and more modes may be used to accommodate various situations. It is desirable that the configuration has a mode of 0
For example, if you have 20 types, you can make even finer adjustments to the shading. 109 is a modem that modulates transmitted data and demodulates received data; 110 is an NCU (Network CU) that switches the telephone line 110a to the modem 109 side or the telephone 111 side
k Control Unit), 111 is an attached telephone. Further, 150 is a public line network. FIG. 2 shows a detailed configuration of the image processing section 102 shown in FIG. 1. In FIG. 2, 200 is a CCD line sensor section of the reading section 101, 201 is a peak hold circuit, and the CCD
The maximum value (maximum potential value) of the line sensor section 200 output is held. The potential peak held by the peak hold circuit 201 is input to the A/D converter 203. The A/D converter 203 sets the reference value 207 as the maximum value and
Depending on the level of the input peak hold value within the range where the ND level is the minimum value, the input peak hold value is converted into corresponding digital data and output to the signal line 208. The signal line 208 becomes an input to the CPU 106, and
06 reads the digital data from this signal line 208 and introduces the reading level from the CCD line sensor section 200, for example when the original is completely white, and uses this value as a reference to read the reading level from the ROM 106.
One of the brightness/density conversion tables shown in FIG. 3 is selected. Table (a) is a brightness/density conversion table when the reading level is high. On the other hand, table (b) is a brightness/density conversion table when the reading level is low, and the overall density is set high for the same brightness data. The CPU 106 reads the selected brightness/density conversion table from the ROM 108 and writes it into the conversion table area 107a of the RAM 107. On the other hand, 202 is a shading correction circuit, which performs shading correction based on the potential peak held by the peak hold circuit 201, and converts the corrected waveform into A.
/D converter 204 as a reference voltage. The A/D converter 204 converts the analog image data read by the CCD line sensor section 200 of the reading section 101 into digital image data with a quantization number of 6 bits. That is, the shading correction circuit 2 which is the data with the highest brightness
Set the reference voltage from 02 to the lightest white (all white) to 64”
(l l l 1.11.), and the GND level is represented by "O" (000000), which is the darkest black (total black) that is the data with the lowest brightness. Note that this image data is brightness data. The luminance data from the A/D converter 204 is sent to a data conversion circuit 205, where it is converted into density data corresponding to the luminance data. This conversion is performed by the A/D conversion circuit 203 described above.
This is done by referring to the conversion table 107a stored in the RAM 107 based on the data. The data converted by the data conversion circuit 205 is transferred to the binarization processing circuit 206.
Image processing is performed and binarized using, for example, an error diffusion method. Then, it is output to the recording unit 103 or the like. As explained above, according to the present embodiment, by selecting the optimum brightness/density conversion table based on the maximum value (maximum potential value) of the output of the CCD line sensor section 200, it is possible to appropriately adapt to input image signals of various specifications. It is possible to output optimally processed images. Furthermore, by selecting a conversion table according to the maximum output of the CCD line sensor unit 200, even when the amount of light from a fluorescent lamp decreases, images near black can be output without becoming faded.

[Other Examples]

In the above embodiment, there are two types of tables, but several types may be prepared depending on the level.
It is also possible to combine it with "dark<", "light", etc. set by the user.Generally, the light intensity of fluorescent lamps changes depending on the temperature, so it is also possible to select a table based on the output of a temperature sensor attached to the device. [Effects of the Invention] As explained above, according to the present invention, by selecting the conversion method of the conversion means based on the maximum value of the input analog signal from the input means, it is possible to appropriately convert input image signals of various specifications. It is possible to output optimally processed images.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of a facsimile machine according to an embodiment of the present invention, FIG. 2 is a detailed configuration diagram of the image processing section shown in FIG. 1, and FIG. FIG. 4 is a diagram showing an example of a brightness-density conversion table, and FIG. 4 is a diagram showing an example of an output signal level from an image sensor. In the figure, 100...system bus, 101...reading section, 102...image processing section, 103...recording section, 10
4... Operating unit, 105... Encoding/decoding unit, 10
6...CPU, 107...RAM, 108...R
OM, 109...modem, iio...NCU, 11
DESCRIPTION OF SYMBOLS 1... Telephone, 150... Public network, 201... Peak hold circuit, 202... Shading correction circuit, 203, 204... A/D converter, 20"5...
- Data conversion circuit, 206... Binarization processing circuit. Special;, 'l'4-+ (, Creation 1 Figure 3 (a) (b) No. 41]

Claims (2)

[Claims] (1) In an image processing device that converts an analog image signal expressed by luminance information into a digital image signal expressed by corresponding density information, an input means for inputting an input analog image signal expressed by luminance information; An analog-to-digital converting means for converting an input analog image signal in the input means into a corresponding digital image signal, and a random access memory, and converting the output signal from the analog-to-digital converting means into a corresponding density in at least two ways. A conversion means that can be converted into data, a processing means that quantizes the density data converted by the conversion means, and a conversion method of the conversion means is selected based on the maximum value of the input analog signal from the input means. An image processing device comprising: selection means. (2) The image processing apparatus according to claim 1, further comprising a plurality of data conversion tables, and the selection means selects one from the plurality of data conversion tables and uses the selected data conversion table in the conversion means. An image processing apparatus characterized in that data is written in a certain random access memory, and the conversion means performs density conversion processing using a data conversion table selected by the selection means.