JPH0683364B2 - Digital color copier - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital color copying machine capable of copying color originals.

2. Description of the Related Art FIG. 3 shows an example of the configuration of a conventional digital color copying machine.

In FIG. 3, 41 is a scanner, 42 is a color correction device, 43 is a printer, 44 is a three primary color image signal, and 45 is a print signal.

The operation of the digital color copying machine constructed as described above will be described below.

In FIG. 3, the scanner 41 is provided with a sensor composed of an element that generates an electric charge according to the intensity of light. The scanner 41 optically reads a document using a sensor, obtains an output as an electrical signal, A / D converts the signal, and then sequentially outputs as a three-primary-color image signal 44 for each pixel. When the A / D conversion is performed on the electrical signal output from the sensor, the scanner does not judge whether or not it exceeds the range that can be A / D converted. The maximum value that the signal can take is output. For example, 0.0 when reading a document with a reflectance of 0%.
For a sensor that outputs 10.0 volts when reading a document with a reflectance of 80%, it is 0.0 using the 8bits A / D converter.
When there is a conventional scanner that outputs 00 _{(16) to} FF ₍₁₆₎ for an input of ~ 10.0 volts, the sensor reads 1 when reading a document with 90% reflectance.
It outputs 1.25 volts, but as a result of A / D conversion, it outputs FF ₍₁₆₎ as the three primary color image signals. After that, the electric signal output from the sensor is
Outputting the maximum value as a three-primary-color image signal when the electric signal exceeds the range that can be A / D converted during D conversion is expressed as “saturated”. The color correction device of 42 inputs the three primary color image signals of 44, and reduces the color difference of the corresponding pixels of the original input from the scanner of 41 and the duplicate output from the printer of 43 to reduce the color difference of 45. Output a print signal. The printer of 43 applies the coloring material to the paper according to the print signal of 45.

Here, the color correction device 42 determines that the value of the three primary color image signal 44 is FF.
_{When (16)} , the reflectance of the input original is 80%.
It is not possible to distinguish whether it was 90% or 90%, and no consideration is given to the indistinguishability.

SUMMARY OF THE INVENTION However, in the digital color copying machine having the above-described structure, when the scanner reads a document of a color having a high reflectance that saturates the three primary color image signals, the three primary color image signals output by the scanner are read. Is the maximum value. At that time, the color correction apparatus performs color correction by assuming that the original document having the reflectance corresponding to the maximum value of the input three primary color image signals is read by the scanner, and outputs the print signal. However, the color of the actual manuscript has a higher reflectance. When the ratio between the three primary color image signals changes due to saturation of some of the three primary color image signals, the hue to be expressed changes, so that there is a problem that colors do not match between the original and the duplicate. there were.

Further, it is also possible to solve the above-mentioned problems by expanding the range in which the electric signals output from the sensor can be A / D converted. However, when trying to reproduce a good color even with a special color such as a fluorescent color that modulates short-wavelength light into long-wavelength light and reflects it, normal colors that are not fluorescent colors and fluorescent colors Since it is not possible to obtain good color reproduction with the same color correction means, there is a problem in that it is not possible to simply widen the range of reflectance that the sensor can read.

In view of the above problems, the invention according to claim 1 can perform good color reproduction even when a document has a pixel having a reflectance exceeding the range of reflectance that can be read by a scanner. The present invention provides a digital color copying machine.

Further, in view of the above problems, the invention according to claim 2 is a good color even for a special color such as a fluorescent color in a manuscript, in which light of a short wavelength is modulated into light of a long wavelength and is reflected. The present invention provides a digital color copying machine that can be reproduced.

In order to solve the above problems, a digital color copying machine according to a first aspect of the present invention is provided with a first color correction device, a second color correction device, a saturation determination device, and a print signal selector. And a first print signal output from the first color correction device and a second print signal output from the second color correction device in response to the saturated color determination signal output from the saturation determination device. It is provided with a configuration of selecting and outputting with a selector.

In order to solve the above problems, a digital color copying machine according to a second aspect of the present invention comprises a first color correcting device, a second color correcting device, a fluorescent color judging device, and a print signal selecting device. The first print signal output by the first color correction device and the second print signal output by the second color correction device are selected by the print signal selector in response to the fluorescent color determination signal output by the fluorescent color determiner. Then, the output is provided.

According to the invention described in claim 1, with the above configuration, even if the pixel of interest is a color having a reflectance higher than the reflectance that can be read by the scanner, a color that can be expressed by the printer by the first color correction device By expressing a color close to that of the original, it is possible to make a faithful copy of the original.

According to the second aspect of the present invention, in addition to the above-described action, the present invention also has a special color such as a fluorescent color in which a pixel of interest modulates short-wavelength light into long-wavelength light and reflects it.
By performing the color correction for the fluorescent color by the first color correction device and expressing the color that can be expressed by the printer with the color close to that of the original, it is possible to make a faithful copy on the original.

Embodiment A digital color copying machine according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing this digital color copying machine. In FIG. 1, 1 is a scanner, 2 is a saturation determination device, 3 is a first color correction device, 4 is a second color correction device, 5
Is a print signal selector, 6 is a printer, 7 is a reading signal of three primary colors, 8 is an image signal of three primary colors, 9 is a saturation determination signal, 10
Is a first print signal, 11 is a second print signal, and 12 is a print signal.

The operation of the digital color copying machine configured as described above will be described below with reference to FIGS. 1 and 4.

In FIG. 1, the scanner 1 optically reads a document. The scanner 1 is provided with a sensor composed of an element that generates an electric charge according to the intensity of light, and the reflectance of the document can be observed as an electric signal using this sensor. In the scanner 1, three types of filters of red (R), green (G), and blue (B) are prepared, the three types of filters are separately passed for one pixel, and the reflectance is observed using a sensor. . The color information of the pixel of interest can be read as the magnitudes of the three types of sensor outputs obtained through these filters and the ratio between the outputs. In the scanner 1, the electric signal output from this sensor is subjected to A / D conversion of 8 bits and output from the scanner as a three primary color image signal 8. Thereafter, each of the three primary color image signals 8 is converted into R according to the type of each filter.
We will call them signal, G signal, and B signal. Also, when the electrical signal output from the sensor is A / D converted, it is judged for each of the three primary color image signals 8 whether it exceeds the range that can be A / D converted, and if it exceeds the range. If so, '1' is set as the three-primary-color reading state signal 7, otherwise, '0'
Is output. Of the three primary color image signals 8, those that exceed the range that can be A / D converted when A / D converted have the maximum value (FF
⁽ ₁₆ ⁾ ). After that, when the electric signal output from the sensor is A / D converted in this way, the maximum value is output as a three-primary-color image signal when the electric signal exceeds the range that can be A / D converted. It is expressed as “saturating”.

The first color correction device 3 inputs the three-primary-color image signal 8 and the three-primary-color reading state signal 7 and outputs the first print signal 10. The first color correction device 3 is realized by a look-up table (hereinafter referred to as LUT), which is a table of numerical values of seven types. FIG. 4 is a diagram for explaining the seven types of LUTs and their operations. FIG. 4 (a) is a LUT used when the'B signal 'of the three primary color image signals is saturated,
FIG. 4B is a LUT used when the'R signal 'of the three primary color image signals is saturated, and FIG. 4C is a LUT used when the'G signal' of the three primary color image signals is saturated. FIG. 4 (d) shows'G signal 'and'B signal' among the three primary color image signals.
LUT used when the image is saturated, FIG. 4 (e) is a LUT used when the'R signal 'and'B signal' of the three primary color image signals are saturated, and FIG. 4 (f) is a three primary color image LUT used when'R signal 'and'G signal' are saturated,
FIG. 4 (g) is a LUT used when the'R signal ',' G signal 'and'B signal' of the three primary color image signals are saturated.

One of the three primary color reading state signals 7 has two states (“0” and “1”), and there are 8 (= 2 ³ ) cases depending on the combination of the states of the three signals. If none of the three primary color image signals 7 is saturated, the second color correction device 4
Is selected by the print signal selector 5, and if this is excluded, there are seven cases, and seven LUTs are required. First, the information on which of the three primary color image signals 8 is saturated is obtained from the three primary color reading state signal 7, and which of the seven types of LUT is to be used is determined accordingly. Using the LUT selected by the three primary color reading status signal 7,
Of the three primary color image signals 7, the remaining unsaturated signals,
First print signal to be output by searching LUT 1
Decide 0. For example, when the R signal of the three primary color image signals 8 is saturated, FIG. 4B is selected.
At that time, the LUT is searched using the values of the G signal and the B signal which are the remaining non-saturated three primary color image signals 7. The set of values stored therein is output as the first print signal.

Here, this LUT confirms the values of the three primary color image signals 8 and the three primary color reading status signals 7 for the colors saturated when actually read by the scanner, and determines the location of the LUT determined by those values. In addition, it was constructed by finding the value of the print signal that becomes visually close when the saturated color is read by the scanner and expressed by the printer and storing it.

The second color correction device 4 reduces the color difference between the corresponding pixels of the original input from the scanner 1 and the duplicate output from the printer 6 for the colors in which the three primary color image signals 8 are not saturated. Thus, the second print signal 11 is output. Specifically, the second print signal 11 is obtained by subjecting the three primary color image signal 8 to a matrix operation of a 3 × 3 matrix,
Has been realized.

The saturation determination unit 2 inputs the three-primary-color reading status signals 7 output from the scanner 1, and outputs "1" if any one of them has a value of "1", and outputs "0" for all three-primary-color reading status signals 7. In case of, '0' is output as the saturation determination signal 9.

The print signal selector 5 selects the first print signal 10 when the saturation determination signal 9 output by the saturation determination unit 2 is “1” and selects the second print signal 11 when the saturation determination signal 9 is “0”, and selects the print signal. Output as 12.

Therefore, if at least one of the three primary color image signals 8 is saturated, the first print signal 10 is output, and if there is no saturated signal, the second print signal 11 is output as the print signal 12. .

The printer 6 adheres the color material to the paper according to the print signal 12.

As described above, according to this embodiment, the first color correction device 3 and the second color correction device 4 are provided, and the second color correction device 4 performs the conventional color correction, and the saturated color is By using the first color correction device 3, it is possible to output to the printer 6 a print signal that is visually close to the color of the pixel of interest when the color of the pixel of interest is expressed by the printer 6, and to reproduce the saturated color. You can improve your sex.

A digital color copying machine according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a digital color copying machine according to the second embodiment of the present invention. In FIG. 2, 21 is a scanner, 22 is a fluorescent color determiner, 23 is a first color correction device, 24 is a second color correction device, 25 is a print signal selector, 26 is a printer,
27 is a three primary color image signal, 28 is a fluorescent color determination signal, 29 is a first print signal, 30 is a second print signal, and 31 is a print signal.

The operation of the digital color copying machine configured as described above will be described below with reference to FIGS. 2 and 4.

In FIG. 2, the scanner 21 optically reads a document. The scanner 21 is equipped with a sensor composed of an element that generates an electric charge according to the intensity of light,
The sensor can be used to observe the reflectance of the document as an electric signal. In the scanner 21, red (R),
Three types of filters, green (G) and blue (B), are prepared, and these three types of filters are separately passed through one pixel, and the reflectance is observed using a sensor. The color information of the pixel of interest can be read as the magnitudes of the three types of sensor outputs obtained through these filters and the ratio between the outputs. In the scanner 21, the electrical signal output from this sensor is A / D converted into 8 bits and 3
The primary color image signal 27 is output from the scanner. Here, when the electric signal obtained as the output of the sensor is subjected to A / D conversion, it is not judged whether or not it exceeds the range in which A / D conversion can be performed. However, if it exceeds the range that can be A / D converted, the image signal of the three primary colors
The maximum value (FF ₍₁₆₎ ) is output as 27.

The first color correction device 23 inputs the three primary color image signals 27, and first compares the three primary color image signals 27 with the threshold value. The threshold value is stored in the first color correction device 23 as a predetermined value. The first print signal 29 is determined and output from the information indicating which of the three primary color image signals 27 exceeds the threshold value and the signal of the three primary color image signals 27 that does not exceed the threshold value. Specifically, the first aspect of the present invention
This is realized by using seven types of LUTs, as in the example of the section.

The second color correction device 24 includes a document input from the scanner 21 and a copy output from the printer 6 for normal colors in which the three primary color image signals 27 do not exceed the threshold values.
The second print signal so that the color difference of the corresponding pixels becomes small.
Outputs 30. Specifically, this is performed by performing a matrix operation of a 3 × 3 matrix on the three primary color image signal 28 to obtain the second
The print signal 30 of is obtained and realized.

The fluorescent color determiner 22 inputs the three primary color image signals 27 and determines whether or not the pixel of interest is a fluorescent color by using the threshold value. The threshold value has the same value as that in the first color correction device 23. If at least one of the input three primary color image signals 27 exceeds the threshold value, the first print signal 29 is output. If none of the three primary color image signals 27 exceeds the threshold value, the second print signal 29 is output. The print signal 30 of the print signal selector
A fluorescent color determination signal 28 selected by 25 is output.

The print signal selector 25 responds to the fluorescent color determination signal 29 output by the fluorescent color determiner 22, selects either the first print signal 29 or the second print signal 30, and outputs it as the print signal 31. .

The printer 26 attaches the coloring material to the paper according to the print signal 31.

As described above, according to the present embodiment, even when the pixel of interest in the document is a special color such as a fluorescent color that modulates short-wavelength light into long-wavelength light and reflects it, the fluorescent color A discriminator 22 discriminates the fluorescent color, and the first color correction device performs the color correction for the fluorescent color, whereby a copy with good color reproducibility can be obtained.

In the first and second embodiments, the second color correction device 4 is realized by matrix calculation, but it may be realized by LUT.

EFFECTS OF THE INVENTION As described above, according to the present invention, by providing the first color correction device, the second color correction device, the saturation determination device, and the print signal selector, the reflectance of the pixel of interest can be read by the scanner. Even a color having the above reflectance can be reproduced faithfully to the original by expressing the color that is closest to the color of the original among the colors that can be expressed by the printer.

Further, by providing the first color correction device, the second color correction device, the fluorescent color determiner, and the print signal selector, short-wavelength light is converted into long-wavelength light such that the pixel of interest is a fluorescent color. When a special color that is modulated and reflected is used, color correction for fluorescent colors is performed by the first color correction device, and the color that is closest to the original color of the colors that can be expressed by the printer is used. , It is possible to make a copy that is faithful to the original.

[Brief description of drawings]

1 is a block diagram of a digital color copying machine in an embodiment of the invention described in claim 1, FIG. 2 is a configuration diagram of a digital color copying machine in an embodiment of the invention described in claim 2, and FIG. FIG. 4 is a block diagram of a digital color copying machine, and FIG. 4 is an explanatory diagram of seven types of LUTs in the first color correction apparatus in the embodiment of the present invention. 1, 21, 41 ... Scanner, 2 ... Saturation determiner, 3, 23 ... First color correction device, 4, 24 ... Second color correction device, 5, 25 ... Print signal selector, 6, 26, 43 ... printer, 7 ... 3 primary color reading status signal, 8, 27, 44 ... 3 primary color image signal, 9 ... saturation determination signal, 10, 29 ... first print signal, 11, 30 …… Second print signal, 12, 31, 45 …… Print signal. 22 ... Fluorescent color judgment device, 28 ... Fluorescent color judgment signal, 42 ... Color correction device.

Claims (2)

[Claims] 1. An optical reading of a document, A / D conversion of a signal obtained as an electric signal, output as a three-primary-color image signal, and the electric signal when the electric signal is A / D converted. , A scanner that outputs as a three-primary-color reading state signal whether or not it exceeds an A / D-convertable range, and the three-primary-color reading state signal is input, and the scanner performs the A / D conversion of the electrical signal. At that time, it is determined whether or not the electric signal has three or more of the three primary color image signals that exceed the range that can be A / D converted, and the determination result is used as a saturation determination signal. A saturation determination device for outputting, the three primary color image signals, and the three primary color reading state signals are input, and the electric signal of the three primary color image signals in the input document exceeds the range where A / D conversion is performed. For pixels with more than one signal And a first color correction device that outputs a first print signal that reduces the color difference between the pixel and the corresponding pixel of the copy, and the three primary color image signals are input, and the electrical signals of the three primary color image signals are input. A second color correction device for outputting a second print signal in which a color difference between a pixel having no signal exceeding the range of A / D conversion of the signal and a corresponding pixel of the copy is reduced And inputs the second print signal and the first print signal, and selects only one of the second print signal and the first print signal in response to the saturated color determination signal. A digital color copying machine comprising a print signal selector for outputting as a print signal and a printer for inputting and printing the print signal. 2. A scanner which optically reads a document, A / D-converts a signal obtained as an electric signal, and outputs it as a three-primary-color image signal, and inputs the three-primary-color image signal,
A fluorescent color discriminator that outputs, as a fluorescent color discrimination signal, whether or not there is one or more signals in which the values of the three primary color image signals exceed a certain threshold, and the three primary color image signals are input. Outputs a first print signal in which a color difference between the pixel and a pixel corresponding to a copy becomes small for a pixel having one or more signals in which the value of the three-primary-color image signal exceeds a certain threshold value in the input document. A first color correction device for inputting the three-primary-color image signals, and selecting a pixel in the input document that has no signal in which the value of the three-primary-color image signal exceeds a certain threshold value. A second color correction device that outputs a second print signal that reduces the color difference from the corresponding pixel of the copy, and the second print signal and the first print signal that are input, and the fluorescent color determination signal In response to either the second print signal or the first print signal. A print signal selector which selects and outputs only one of the print signal, inputting the print signal, a digital color copying machine, characterized by comprising a printer for printing.