JP3507097B2 - Image processing apparatus and image processing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and an image processing method for converting an input image into a predetermined image.

[0002]

2. Description of the Related Art Recently, color information of an original is converted into a color signal by a photoelectric conversion element such as a color CCD, and an area determined to have a predetermined color by this color signal is replaced with a predetermined monochrome density signal. A digital copying machine that can obtain a monochrome image has been proposed.

As a result, it is possible to print out a monochrome image in which the color portion of the input color image can be identified by the monochrome printer.

By the way, a normal copying machine can set a copy density.

[0005]

However, if the copy density is changed in a digital copying machine that replaces the above-mentioned predetermined color with a predetermined monochrome density, the predetermined density to be replaced also changes, and a printout is made. There is a problem that it is not possible to know how many colors the original image was composed from the recorded image and a problem that a beautiful printed image cannot be obtained.

[0006]

An image processing apparatus of the present invention comprises a discriminating means for discriminating a predetermined color in an original image, and the discriminating means.
The area with the specified color determined by the method is set to the specified density.
A first density converting means for converting, a setting means for setting the density of the output image with respect to the density of the original image, and a density converting process for the original image based on the density set by the setting means . Density conversion means and the first density
It is characterized by further comprising control means for controlling so that the density conversion processing is not performed by the second density conversion means on the area converted into the predetermined density by the conversion means . The image processing method of the present invention, a determination step of determining a predetermined color in the original image, the predetermined color is discriminated by said discriminating step
The first density conversion step for converting a region having
And a setting step for setting the density of the output image with respect to the density of the original image, and a density conversion process is performed on the original image based on the density set by the setting step.
The second density conversion step and the first density conversion step
Wherein the region to be converted to a predetermined concentration by up second
It is characterized in that it has a control step for controlling so that the density conversion processing is not performed by the density conversion step .

[0007]

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

(Structure of Copying Machine) FIG. 1 is a sectional view for explaining the structure of a copying machine which is an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an original feeding device for automatically feeding originals, which feeds placed originals one by one or two in succession to a predetermined position on an original glass surface 2. To do. Reference numeral 4 denotes a scanner including an exposure lamp 3 for irradiating a document, a scanning mirror 5 for exposing and scanning the document, and the like.
After the document is placed on the platen glass surface 2 by the document feeding device 1, the scanner 4 is scanned in the direction A, and the reflected light from the document is scanned through the scanning mirrors 5 to 7 and the lens 8 and the CCD image sensor unit 101. Image. Reference numeral 10 denotes an exposure control unit including a laser scanner, which is a controller unit CONT
The light beam modulated on the basis of the image data output from the image signal controller is irradiated onto the photoconductor 11. A red developing device 12 and a black developing device 13 visualize the electrostatic latent image formed on the photoconductor 11 with a predetermined developer (toner). One of the developing devices 12 and 13 is disposed close to the photosensitive drum 11 by the developing device switching device 30, and the other is disposed to the photosensitive drum 1.
It will be evacuated from the beginning. Further, when performing the multiple phenomenon, the controller unit CONT controls the developing device switching device 30. A sheet stacking unit 14 and 15 stacks and stores standard size sheets. The sheet is transferred from the stacking units 14 and 15 to the registration roller 2 by driving the feeding roller.
The sheet is fed to the arrangement position 5 and is fed at such a timing that the leading edge of the image formed on the photoconductor 11 by the registration roller 2 and the leading edge of the sheet are aligned.

Reference numeral 16 denotes a transfer / separation charger, which transfers the toner image developed on the photoconductor 11 to a sheet, and then the photoconductor 11
The sheet is separated from the sheet, and the fixing unit 17
To fix the toner on the sheet. 18 is a discharge roller,
The recorded sheet is discharged to the tray 20. Reference numeral 21 switches whether the sheet recorded by the direction flapper is discharged to the tray 20 side or is conveyed to the internal conveyance paths 22, 23 and 24.

For double-sided recording, the flapper 21 is placed on the tray 20.
After the sheet passes through the sheet discharge sensor 19, the sheet discharge roller 18 is rotated in the direction opposite to the sheet discharge direction, and at the same time, the flapper 21 is raised to make a copy. The finished sheets are stored in the intermediate tray 24 via the transport paths 22 and 23. The sheet stored in the intermediate tray 24 is fed at the time of the next back surface recording, and the back surface of the sheet is transferred.

During multiple recording, the flapper 21 is raised to store the recorded sheet in the intermediate tray 24 via the conveyance paths 22 and 23. The sheets stored in the intermediate tray 24 are fed at the time of the next second recording, and the multiple transfer is performed.

(Operation Unit) FIG. 2 shows a part of the operation unit of the copying machine of this embodiment.

A display unit 200 displays the state of the apparatus, the number of copies, the copy magnification, and the copy paper size, and displays the contents to be set during the copy mode setting.

A reduction / enlargement key 201 is used for reducing or enlarging a standard size image to another standard size image.

Reference numeral 202 denotes a cassette selection key which selects a cassette stage in which sheets are stored.

A reset key 203 operates as a key for returning to the standard mode.

Reference numeral 204 is a copy start key.

Reference numeral 205 is a ten-key pad, which is used when inputting a numerical value.

Reference numerals 206, 207, and 208 denote copy density keys. The operator 206 presses the key 207 to make the copy density lighter, and the key 208 to make the copy density darker. . When the darkest copy is made, the LED 211 lights up.
LED2 for the thinnest copy with ED210
09 emits light.

Reference numeral 212 is a key for setting a color-density conversion mode for converting the color components in the original document to a density corresponding to the color, and the operator presses this key 212 when setting the color-density conversion mode.

FIG. 3 is a block diagram of the copying machine of this embodiment.

The full-color original is exposed by the exposure lamp 3 and the reflected color image is read by the CCD image sensor 1.
01, imaged image signal is processed and processed,
It is designed to output to the printer 103.

The color information of the original 100 is obtained by the image reading unit 1.
CCD image sensor 1 through lens 101a of 01
The image is formed at 01b. CCD image sensor 101b
Reads each line at 400 dpi for R (red), G (green), and B (blue). The read signal is output as an analog signal and input to the A / D converter 101c that converts the analog signal into a digital signal. The digital signal from the A / D converter 101c is input to the image processing unit 102. In the image processing unit 102, the shading correction circuit 102a performs shading correction, and R, G,
Image data of 8 bits for each B is generated. The data processing unit 102b discriminates the color of the read image data and converts it into a specific density signal corresponding to it, and further, the brightness / density conversion unit 102c converts the brightness data into density data, and prints the print data for the printer 103. To generate. The printer 103 has a control circuit such as a motor that conveys a sheet, a laser recording unit that writes input image data on a photosensitive drum, and a development control circuit that performs development. Also,
The CPU circuit unit 104 includes a CPU 104a and a ROM 104.
b, a RAM 104c, and controls the image reading unit 101, the image processing unit 102, the printer 103, etc., and collectively controls the sequence control of the copying machine.

FIG. 4 is a detailed block diagram of the data processing unit 102b.

In the luminance signal generator 110, image data over the entire wavelength region that has been color-synthesized from the R, G, B image data read by the CCD image sensor 101b,
That is, it produces black-and-white image data. This is for printing a color original image in black and white. In the luminance signal generation unit 110, R, G, B input
(R +
G + B) / 3 is calculated to generate a luminance signal.

The R, G, and B image data are simultaneously input to the max, mid, and min detectors 120. Reference numerals 120 to 132 constitute a color discriminating unit. The color discriminating units 120 to 128 detect color components of a document image for performing image processing for outputting a color image portion with a density corresponding to a color. It is a thing.

The hue signal is used to detect the colors in the color discriminating units 120 to 128. This is to enable accurate determination even when the same color has different vividness and brightness. (To be exact, it is different from the commonly used hue, but in the following explanation, "hue"
Explained as).

First, an outline of the color detection method will be described.

The input R, G, and B data are each 8-bit data, and have information for a total of 2 ²⁴ colors.
Therefore, it is expensive in terms of its scale.
In the present invention, in consideration of the above points, the following processing is performed using the hue described above.

The input R, G, B data is first input to the max / mid / min detection section 120 which discriminates its magnitude. The max / mid / min detection unit 120
By comparing each input data using a comparator, the order of the size of R, G, B data is obtained, and the max value (maximum value) and mid value (intermediate value) from the input R, G, B data. , Min value (minimum value) is obtained and the obtained result is output.

It is known that the color space is represented by saturation, lightness, and hue, as is known in Munsell color solids and the like. That is, the input R, G, and B data are converted into planes,
That is, it is necessary to convert it into two-dimensional data. Therefore, using the fact that the common part of R, G, B, that is, the minimum value of R, G, B, min (R, G, B), is an achromatic component, min (R, G, B) Is subtracted from each R, G, B data, and the remaining information is used as a chromatic color component. This achieves conversion to a two-dimensional input color space with a simple configuration.

As shown in FIG. 5, the plane thus converted is divided into six colors arranged on the circumference of 0 ° to 360 °, and the colors of R, G and B to be input are set. In order: R>G> B, R>B> G, G>B> R, G>R>
Color discrimination can be performed based on the information of B, B>G> R, and B>R> G.

Due to the above conversion processing, the output max
Subtractor 1 to subtract the achromatic component from the value and the mid value
21 and 122, the min value is subtracted from the max value and the mid value, and the subtraction result is input to the hue detection unit 123 together with the rank signal indicating the order of the sizes of R, G, and B. The hue detection unit 123 is a ROM that stores a look-up table.
It is composed of.

The angle on the plane of FIG. 5 is (max-min)
The order of the value, the (mid-min) value, and the sizes of R, G, and B can be calculated.
In advance, the rank signal, (max-min) value, (mid-
The hue value corresponding to the (min) value is stored. When the rank signal and the (max-min) value and the (mid-min) value are input, the corresponding hue value is output.

As a result, an LUT (look-up table) or the like is used based on the order of the sizes of R, G and B to be input and the maximum value and the intermediate value of R, G and B to be input. With such a simple configuration, the three-dimensional input color space can be converted into the two-dimensional color space and the corresponding hue value can be obtained.

The hue value output from the hue detection unit 123 is input to the window comparator 140. The window comparator 140 determines whether the hue value from the hue detection unit 123 is a specific color value. This example is 5
Color determination can be performed, and four other circuits similar to 124 to 130 are connected in parallel in the window comparator 140.

Registers 124 and 127 are connected to the comparators 125 and 126, respectively.
4, the lower limit value and the upper limit value of the hue to be detected are set.

Assuming that the setting reference value of the comparator 125 is a1, the comparator 125 outputs "1" when the input hue data is (input hue data)> (a1).

Similarly, when the setting reference value of the comparator 126 is a2, the comparator 126 is configured to output "1" for the input hue data when (input hue data) <(a2).

Therefore, (a1) <(input hue data) <
In the case of (a2), "1" is output from the AND gate 128 in the subsequent stage.

Then, the register 129 stores C as described later.
The PU 104 sets a predetermined density value corresponding to the hue data. AND gate 130 is AN
AN of the output of the D gate 128 and the output of the register 129
D, and the selector 111 via the OR gate 132
Entered in.

The output of the AND gate 128 is sent to the selector 11 via the OR gate 131 and the AND gate 133.
Input to 1. When the color-density conversion mode is set by the key 212, the CPU 104 operates the AND gate 1
“1” is output to 33, and “0” is output if not set.

The circuit for detecting the other colors in the window comparator 140 has the same configuration, and the reference value set by the comparator is a value corresponding to each detected color. Then, when the number of determination colors is increased, a similar configuration may be added.

In the selector 111, the OR gate 13
When the output of 1 is "1" and the signal from the CPU 104 input to the AND gate 133 is "1", the output signal of the OR gate 132 is selected, and otherwise,
The output of the brightness signal from the brightness signal generation unit 110 is selected. This output signal is converted into density data by the brightness / density converter 102c and input to the printer 103.

(Calculation of Density Value) As described above, the copy density keys 206, 207, and 208 can be used to select from nine levels of states from the darkest copy to the lightest copy.

The operation of the copy density is realized by changing the reference table used when converting the brightness data in the brightness density converter 102c into the density data.

The brightness / density conversion section 102c stores a randomly accessible reference table, and nine reference tables for converting brightness data into density data in advance (the reference tables are referred to as F1 to F9). . The reference tables F1 to F9 are copy density keys 206 and 20.
7, 208.

FIG. 6 shows three reference tables for the darkest copy, the standard state, and the lightest copy. The F1 reference table is used when the darkest copy is designated by the operation unit, and F5 is used in the standard state, and the F9 reference table is used when the lightest copy is designated.

In FIG. 6, when luminance data of K1 is input, it is converted into data of B1 when the reference table of F1 is used, and when it is F5, B5, F
In the case of 9, it will be converted into the data of B9. Further, the printer 103 prints darker as the density data is larger, and lighter as the density data is smaller. That is, even if the same luminance data is input, the output density data changes depending on the reference table used. As described above, when the color-density conversion mode is set by the color-density setting key 212, the predetermined color in the input image is converted into the image of the predetermined density. , 207, 208, the density of the color-density converted density image also changes.

In order to make the density of the predetermined color portion constant regardless of the reference table, it is necessary to obtain the input brightness data from the output density data and set the input brightness data in the register 129. As shown in FIG. 7, for example, in order to output the density data D1, when the reference data of F1 is used, the input luminance data is A1,
It is necessary to use the input brightness data of A5 for the reference data of F5 and A9 for F9.

In this embodiment, nine reference tables for converting the luminance data into the density data are stored in advance in the RAM 104c, and the copy density key 20 on the operation unit is used.
The reference table is selected according to the densities designated by 6, 207, and 208, and is read out by the CPU 104a at any time.

The input brightness data is calculated based on a program stored in the ROM 104b in advance. The calculation method will be described in detail with reference to the flowchart shown in FIG.

Since five colors can be discriminated in this embodiment, the density values to be converted into fixed density images corresponding to the colors are also five, A [0] to A [4].

Output density data is X [I] (0≤I≤4)
And input luminance data at that time is A [I] (0 ≦ I ≦
4) should be obtained.

The input luminance data J (0≤J≤2
55) output density data in B [J] (0 ≦ J ≦ 255)
Then, B [J] and X [I] are compared with each other to find J when they are equal or the difference is the smallest. That is, J at this time is A [I].

In the flowchart shown in FIG. 6, initial settings are made in steps S1, S2 and S3, and X [I] and B
[J] are compared (step S4), and if they are equal, J is substituted for the desired A [I] (step S9). If they are not equal, the difference between X [I] and B [J] is calculated and substituted into BUF (steps S5 and S6). When the value of BUF is smaller than the value of DEF (step S7), the value of DEF is changed to the value of BUF (step S8), and the value of A [I] is set to J.
Substitute in and update. (Step S10) Next, the value of J is changed (step S11), and the process is repeated until J reaches a maximum of 255 (step S12). Furthermore, A [I] is 5
The above steps are repeated until one is obtained (steps S13 and S14).

A [0] to A obtained in this way
The CPU 104a sets [4] in a register such as the register 129. A [0] is set in the register 129, and A [1] to A [4] are also set in the same register. (Registers are omitted.) The flow of FIG. 8 is performed after the copy start key 204 is pressed, and thereafter, operations such as document reading are performed.

Therefore, the window comparators 125, 1
26, etc., when it is determined that the color is a detected color, the set density value A [I] set in the register is output,
A [I] is X [I] in the brightness density conversion unit 102c.
, Or the value closest to X [I],
The printer 103 can always print with the same density.

FIG. 9 is a schematic diagram for calculating the input luminance data for each color based on the above-mentioned program when the luminance density conversion unit 102c is set to perform conversion using the reference table F5. In FIG. 9, X [0] to X
[4] is a predetermined output density value for each color. The input brightness data A [0] to A [0] A are converted into the respective output density values after being converted by the brightness density converting unit 102c.
[4] is required. These input luminance data A [0]
~ A [4] is five registers 12 by the CPU 104.
Set to 9. Then, when the colors of the input image are determined to be the predetermined colors by the comparators 125 and 126, the input brightness data set in the register 129 is output to the brightness density conversion unit 102c, and the brightness density conversion unit 102 or Output density data corresponding to the input brightness data is output to the printer 103.

FIG. 10 is a diagram showing an example of the configuration of another data processing unit 102b and luminance density conversion unit 102c.

FIG. 10 has the same configuration except that the value set in the register 129 and the position of the selector 111 are different from those in FIG. The signal from the luminance signal generation unit 110 is directly input to the luminance density conversion unit 102c. The signal from the brightness / density converter 102c and the data from the register 129 are input to the selector 111, and the comparators 125 and 12
Selection is made by the judgment signal of 6. The output density data X [0] corresponding to a predetermined color is stored in the register 129.
.. X [4] are set by the CPU 104, and when the color in the input image is a predetermined color, the output density data set in the register 129 in the color area is output to the printer 103. In the case of this configuration, it is not necessary to consider the reference table used in the brightness / density conversion unit 102c.

It is also possible to apply such a structure to a structure for converting the color in the input image into a pattern image. For example, the part of the register 129 in FIG. 10 is replaced with a memory in which a pattern image is stored in the form of output density data in advance, and a part corresponding to a predetermined color is provided with a predetermined pattern through the brightness / density conversion part 102c. Instead, it can be output to the printer 103.

It should be noted that these embodiments may be applied to input images from a computer, a file device, or a facsimile device other than the reader, or may be applied to output to a computer, a file device, or a facsimile device other than a printer. Is also possible.

[0065]

As described above, according to the present invention,
When the first image processing is performed on the area of the predetermined color, the second image processing is invalidated on the area. Therefore, the image subjected to the first image processing is the second image. There is no change due to the processing, and it is possible to obtain the output image as the user desires.

[Brief description of drawings]

FIG. 1 is a sectional view of a copying machine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a part of an operation unit of a copying machine.

FIG. 3 is a block diagram for performing image processing of a copying machine.

FIG. 4 is a detailed block diagram of a data processing unit 102b.

FIG. 5 is a diagram illustrating a hue.

FIG. 6 is a diagram showing a reference table in the brightness density conversion unit 102c.

FIG. 7 is a diagram showing a concept of obtaining a register setting value from a reference table in the brightness / density converting unit 102c.

FIG. 8 is a flowchart for obtaining a register setting unit.

FIG. 9 is a schematic diagram for obtaining register setting values.

FIG. 10 is a data processing unit 102b and a luminance density conversion unit 1.
It is a block diagram of 02c.

Continuation of the front page (56) References JP 63-46071 (JP, A) JP 63-280577 (JP, A) JP 61-285866 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H04N 1/46-1/52 H04N 1/60

Claims (2)

(57) [Claims] 1. A discriminating means for discriminating a predetermined color in an original image, and a region having a predetermined color discriminated by the discriminating means is predetermined.
First density conversion means for converting the density of the output image to the density of the original image, and a density conversion process for the original image based on the density set by the setting means. Second density conversion means to be applied, and control for controlling so that the second density conversion means does not perform density conversion processing on the area converted to a predetermined density by the first density conversion means. An image processing apparatus comprising means. 2. A discrimination step of discriminating a predetermined color in an original image, and an area having a predetermined color discriminated in the discrimination step.
A first density conversion step of converting to a predetermined density, a setting step of setting the density of the output image with respect to the density of the original image, and a density conversion process for the original image based on the density set by the setting step. A second density conversion step of applying the density and a first density conversion step of converting the density to a predetermined density.
The image processing method further comprises a control step of controlling so that the density conversion processing is not performed on the region to be processed by the second density conversion step .