Digital copying apparatus with a display

An apparatus for copying a document in which an operation unit is provided separately from a copying unit. The operation unit includes a memory to store the digital image signals inputted from the copying unit, a display to display the digital image on a screen, and an operation board to convert the display image into a desired image. The copy unit makes a copy image corresponding to the desired image on a recording material.

BACKGROUND OF THE INVENTION 
There has been an increase in the number of the additive functions of the 
copying machine, resulting in a complicated operation to such an extent 
that the user cannot make use of all functions. Since he does not know how 
copying is performed, he has to make several test copies to get a copy 
having the desired dimensions, layout and colors. Since he is not very 
fond of such test copies, he has often avoided using effective additive 
functions. To assist understanding of the user for solution of this 
problem, a little larger display unit has been provided, and the messages 
have been displayed in kanji (Chinese characters) or hiragana (Japanese 
characters), or editors or a variety of semiautomatic functions have been 
added, which have been insufficient in the following respects: For 
example, it is not easy for the user to determine what magnification 
should be selected to get the desired size in the case of the zooming 
function. Some machines provide the automatic magnification setting 
function; however, since it uses the method of calculating magnification 
according to the specified paper size, it cannot meet the requirement of 
magnifying part of the original, for example. 
Some machines calculate the magnification rate from input values on the 
coordinates, but this requires precise user operation, often resulting in 
operation errors. With respect to density adjustment and color balance, 
several test copies must often be taken to determine the influence given 
to the picture by one graduation on the adjust button. Namely, the display 
on the conventional control section has failed to determine if the current 
setting is correct to get the desired copy style, therefore, a 
considerable experience has been required to make an effective use of the 
additive function without test copies. Furthermore, the unit price for the 
full-color copy has been much higher than that of the black/white copy, so 
it is uneconomical to take many test copies. 
The primary objective of the present invention is to provide the digital 
copying machine featuring extremely excellent maneuverability, which 
permits pictorial confirmation of the copy style, to ensure precise 
operation of the additive function by eliminating the need of test copies 
when the additive function is used, as described above. 
The present invention relates to the color balance control device which, as 
the said additive function operating device eliminating the need of test 
copies, converts the colored original including photographs and printed 
matters into electric signals, these signals being output on the color 
television monitor or full color printer via the control circuit. 
Color balance in the conventional full color copy mode has been controlled 
by adjusting the magnitude of the signals for red, green and blue, or 
cyan, magenta and yellow (black) constituting the color components by the 
control key on the control panel. In this case, some knowledge or skill on 
color mixing has been required for the operation, and this has been 
difficult for normal users. For example, when the entire page of the 
original is brownish, color balance can be controlled so as to cancel it. 
The user has to operate the control key to control the color balance while 
considering color components of the brown, their ratio and quality. This 
control is not very easy for the user who has little knowledge about color 
mixing, often causing operation errors. 
This present invention provides an easy-to-use means for color balance 
control by electronic means to solve the said problems. 
For the user with little knowledge about color mixing, it is easy to 
specify the color to be output as achromatic color (gray) in the original. 
For example, it can be easily considered that the black character or the 
paper texture should be adjusted to in achromatic color in general cases. 
When the original is output on the color display screen or the paper, the 
user can easily identify if the part to be output in achromatic color 
(black character or the paper texture) is covered with several colors. He 
can easily identify the case when the entire paper is covered by colors. 
Thus, the second object in the present invention is to provide the color 
balance control device which ensures that all colors are adjusted as the 
user desires and that the expected gray part is certainly output in gray, 
if the user identifies the said colors and specified them, without having 
to consider the color components. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is achieved by the digital 
copying machine provided with an image reading means which obtains the 
image signal by scanning the original and converting it into the electric 
signal, an image processing means which provides image processing to the 
image signal, an image recording means which records the image signal 
having undergone image processing according to the color material of the 
CMYK, a first operation means incorporated in the machine and a second 
operation means located separately from the machine; the first operation 
means comprising the first operation key, display section, CPU and 
parameter, and the parameter memory having operation parameters to operate 
the image reading section, image processing section and image recording 
section, wherein the CPU inputs the signal from the operation key, 
converts it into the operation parameter, stores it into the parameter 
memory and, at the same time, causes the operation parameter setting 
conditions to be displayed on the display unit, the second operation means 
comprising the external CPU, coordinates input device, the second 
operation key, color display device and image memory, wherein the external 
CPU inputs the signal from the coordinates input device and operation key, 
converts it into the operation parameter, inputs the image signals 
obtained from the said image reading means while skipping a part or all of 
these signals, causes them to be stored into the image memory, and inputs 
or outputs the operation parameter from the parameter memory through the 
CPU of the machine, wherein the said second operation means permits part 
or all of the operations which can be done from said first operation 
means, the image signal stored in the said image memory is processed on 
the basis of the parameter in parameter memory or external CPU, the 
processed image is displayed on the color display unit, and the copy style 
can be identified before being copied. 
The second object of the prevent invention is achieved by the image color 
balance control device which determines the chromaticity, processing mode 
and image density by specifying the two-dimensional coordinates, 
comprising an operation section which produces coordinates, chromaticity 
signal, processing mode signal and image density signal, a signal 
converting means which converts the said chromaticity signal into the 
signal for each of the color components (cyan, magenta and yellow or red, 
green and blue), a first calculation means to get the coefficient signal 
value for each of the color components by the calculation of said 
processing mode signal value, said signal mode value for each of the color 
components and said density control signal value, and a second calculation 
means to multiply the image signal value for each of the picture elements 
obtained from scanning the original, by the coefficient signal value for 
each of the said component to be obtained from the said first calculation 
means, and to output the result of this multiplication. 
Namely, when the color balance control device according to the present 
invention is used, color samples are displayed on the color display in 
advance; if one of said samples is specified by the user, the color 
balance works towards the color specified by the user, thereby controlling 
the color balance. Or the color picture elements to be subjected to color 
balance control are displayed on the color display; when the part to be 
adjusted to gray is specified, the color balance works so that part turns 
gray, thereby controlling the color balance. Furthermore, these two types 
are switched automatically. 
The color balance control device also provides density control in addition 
to color balance control.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 represents the configuration of the present invention, wherein 100 
denotes the digital copying machine provided with the first operation 
means 200, and 310 denotes the external CPU (2) (computer), constituting 
part of the second operation means 300, the first operation means 200 of 
the digital copying machine 100 and computer 310 being capable of 
communication by cable 400 or other communication means. 
FIG. 2 is a sectional view representing an embodiment of digital copying 
machine 100. This digital copying machine 100 comprises image reading 
section A, image processing section B, laser writing section C and image 
forming section CPU D. 
The top of the copying machine is provided with the original mount 
comprising the transparent glass plate, and the table 11 comprising the 
original cover to cover the original placed on the original mount. The 
position below the original mount of the machine is provided image reading 
section A comprising first mirror 12, second mirror 13, main lens 20 and 
color CCD 23. The first mirror unit 12 is provided with exposure lamp 14 
and first mirror 15 is mounted so that it can be moved straight in the 
direction parallel to the said original mount and to the left and right of 
the drawing; it optically scans the entire surface of the original. The 
second mirror 13 is provided with the second mirror 16 and third mirror 17 
designed in an integral structure, and makes straight movement in the same 
direction to the right and left at the speed half that of the first mirror 
12 so as to ensure the specified light path at all times. 
Needless to say, second mirror 13 moves parallel to the original mount as 
in the case of the first mirror 12. The image of the original placed on 
the original table illuminated by exposure lamp 14 is formed on the color 
CCD 23 via first mirror 15, second mirror 16 and third mirror 17 by main 
lens 20. The above description relates to the scanning operation. When the 
scanning has completed, the first mirror 12 and second mirror 13 return, 
waiting for the next copying operation. 
The image data of each color obtained from said color VVF 23 is processed 
by the image processing section B and is output from laser writing section 
C as image signal. 
Laser writing section C is composes of drive motor 31, polygon mirror 32, f 
.theta. lens (not illustrated), compensating lens (not illustrated), 
semiconductor laser (not illustrated) and its drive circuit (not 
illustrated). The drive circuit within the laser writing section provides 
on-off control of the semiconductor laser on the basis of the said signal. 
Image forming section CPU D comprises electric charger 35, image exposure 
section 55, developers 36Y, 36M, 36C and 36BK, transfer unit 37, separator 
38 and cleaning unit 39 laid out on the circumference of photosensitive 
drum 30, an image former, and paper feed cassette 40 located close to 
sensitive drum 30, feed belt 44 and fuser 45. 
For said developer 36Y, 36M, 36C and 36BK, developer 36Y is located on the 
most upstream position of the periphery of photosensitive drum 30, and 
developer 36BK accommodating the black toner BK is located on the most 
downstream position. The color toner and black toner stored in developers 
36Y, 36M, 36C and 36BK will not be described here since the extensively 
known toners are used. 
In the said copying machine, each process of said image reading section A, 
image processing section B, laser writing section C and image forming 
section CPU D are operated by the pressure of the copy button installed on 
the operation unit outside the machine, thereby forming the colored copy 
image. Namely, copying operation is started when the image signal from 
image reading section A has been input into laser writing section C 
through image processing section B. That is, photosensitive drum 30 
rotates in the clockwise direction as illustrated by the arrow mark. It is 
charged uniformly by the electric charger 35 at first. At image exposure 
section 55, the operation is performed by laser beam to laser writing 
section C for the yellow (Y') image corresponding to the image of the 
original, thereby forming a Y-image electrostatic latent image. In said 
electrostatic latent image on the photosensitive drum 30, reserve 
development due to the Y toner is caused by developer 36Y, and the visible 
Y toner image is created. In other words, d.c. or a.c. bias voltage is 
applied to the developer sleeve incorporating the magnet roll of developer 
36Y, and non-contact development is caused by two-component non-contact 
developing powder, forming the Y-toner image. The photosensitive drum 30 
which causes creation of the said Y-toner image passes below the cleaning 
unit 39 which is retracted, and starts the second rotation. Then charging 
is performed by electric charger 35 and laser beam writing of the magenta 
(M) image is performed by laser writing section C. Then electrostatic 
latent image of magenta (M) image is formed on the said Y-toner image. 
This latent image is reversed and developed by the developer 36M storing 
the magenta toner, and is turned into M-toner image. This is followed by 
superimposition and formation of the cyan (C) toner image and black (BK) 
toner image. 
The transfer paper P which is fed sheet by sheet by paper feed roller 41 
from the paper feed cassette 40 which stores the transfer paper P as 
transfer material is, and is then fed out onto photosensitive drum 30 by 
timing roller 42 which operates in synchronism with the said toner image 
on photosensitive drum 30. The toner image on photosensitive drum 30 is 
transferred on this transfer paper P by the action of transfer unit 37, 
and is separated from photosensitive drum 30 by separator 38. After that, 
it is fed to fuser 45 by through feed belt 44, with the toner image facing 
upward. 
The transfer paper P subjected to fusing in said fuser 45 is ejected out of 
the copying machine, while said photosensitive drum 30 continues rotating. 
The toner remaining on the surface without being transferred is collected 
and cleaned by the cleaning unit 39A which has ceased to be retracted, and 
the machine waits for the next copying operation. 
The digital copying machine 100 is provided with first operation means 200 
which is built in the machine. The first operation means 200 comprises the 
first operation key 210, display section 220, internal CPU (1) 230, 
parameter and parameter memory 240. 
The second operation means 300 which can be communicated by external cable 
400 is provided with CPU (2) 310, coordinates input device 320, second 
operation key 330, CRT display 340 which is capable of full color display 
and image memory 350. 
The storage device of the CPU (2) 310 stores the program which commands 
functioning as second operation means 300, so execution of said program 
causes operation as second operation means 300. Unless said program is 
executed, digital copying machine 100 can be operated only by the first 
operation means 200. The CPU (2) 310 has computer functions original 
thereto. 
The first operation means 200 on the digital copying machine 100 is 
provided with various buttons 210 including the copy buttons for operation 
and LCD (liquid crystal) or LED display section 220. 
FIG. 3 shows an embodiment of the function block. The block can be divided 
into two portions; the portion on the machine (digital copying machine 100 
and first operation means 200) side and the external portion (second 
operation means 300). The portion on the machine side comprises image 
reading section A, image processing section B, image recording sections C 
and D, control CPU E, parameter memory 240, CPU (1) 230, display section 
220 and first operation key 210; this portion is the "digital copying 
machine." The external portion comprises CPU (2) 310, image memory 350, 
CRT display 340, and second operation key 330 (keyboard and mouse); this 
portion corresponds to the personal computer and work station. 
The parameter memory is a non-volatile SRAM to store necessary operation 
parameters. 
The information input from first operation key 210 is converted into the 
operation parameter by CPU (1) 230, and is stored in parameter memory 240. 
The display section 220 references the operation parameter value inside 
parameter memory 240, and displays the operation parameter value on the 
LED or LCD panel on display section 220. In the same way, the information 
input from second operation key 330 is processed by CPU (2) 310, is fed as 
operation parameter to parameter memory 240 via CPU (1) 230, and is 
stored. At the same time, part or all of the parameter set states are 
displayed on the display section 220 and external CRT display 340. 
Namely, the parameter for additive function can be set from either first 
operation key 210 or second operation key 330. When the operation 
parameter is set from one of these keys, the operation mode is displayed 
on display section 220 and CRT display 340. 
Assume that the original is already placed on the original mount. 
Select the copy paper size, and input this information from one of the 
operations keys 210 and 330. For example, if the first operation means 200 
is used for input, the information is stored in parameter memory 240 via 
first operation key 210 and CPU (1) 230. If second operation means 300 is 
used, the information is stored in the parameter memory 240 via second 
operation key 330, computer 310 and CPU (1) 230. The second operation key 
330 is provided with a copy style button to confirm the copy style. 
Turning on this button causes the magnification, color and style for 
copying to be displayed on the CRT display 340. Firstly, the ON signal of 
the copy style button is fed to the parameter memory via second operation 
key 330, CPU (2) 310 and CPU (1) 230 and stored there. The CPU (1) 230 and 
CPU (2) 310 stores the ON signal in parameter memory 240, and disables 
part of the parameter changes by operation keys 210 and 330, until it is 
released. This prevents the operation error to a certain extent. 
Furthermore, CPU (2) 310 is ready to accept the image signal from image 
reading section A. On the other hand, the control CPU E controls the 
operations of the image recording section comprising the image reading 
section A, image processing section B, laser writing section C and image 
forming section CPU D, and always supervises parameter memory 240. When it 
detects the ON signal, image reading section A scans the original, and 
sends the image signal to CPU (2) 310. The CPU (2) 310 gives consideration 
to the picture elements which can be displayed on CRT display 340 and the 
original mount size and resolution of the image reading section A, and 
skips the image data as required. Thus the data is stored in the image 
memory 350. The image data stored in image memory 350 is displayed on CRT 
display 340. After pre-scanning is completed, the ON signal of the copy 
style button inside parameter memory 240 is cleared, and the system is 
again ready for parameter change. The CPU (2) 310 performs simulation of 
the additive function based on the parameter from parameter memory 240. 
This enables the system to calculate the magnification, color and style 
for copying, according to how the parameters are set, and the results are 
pictorially displayed on the CRT display 340. 
Additive functions to be operated from second operation key 330 and 
coordinates input device 320 may be vertical and horizontal independent 
magnification, magnification change rate, color control, region 
specification or any others. It is essential, however, that the parameter 
representing the content of the additive function be stored in parameter 
memory 240, and correct function be performed when the parameter is 
referenced by image reading section A, image processing section B, image 
recording sections C and D, and control CPU (E). 
Repeat confirmation of the copy style on CRT display 340. When the desired 
copy style is obtained on CRT display 340, press the buttons of first 
operation key 210 on the digital copying machine 100. Then the copying 
operation is performed and the hard copy of the copy style displayed on 
the CRT display 340 is output. Of course, the copy operation may be 
started by the remote type. 
The copy ON signal is firstly stored in parameter memory 240 via the first 
operation key 210 and CPU (1) 230. 
When the CPU (1) 230 and CPU (2) 310 have detected the ON signal in the 
parameter memory 240, the system disables part of the parameter change 
made by operation keys 210 and 330, until it is released. When the CPU (E) 
has detected the ON signal, it controls the image reading section A, image 
processing section B, and image recording sections C and D. The image 
reading section A, image processing section B, and image recording 
sections C and D enter the parameter from parameter memory 240, and 
copying operation is performed in synchronism. 
As described above, the present invention ensures precise operation of the 
additive function while the copy style is checked, and provides the 
digital copying machine which does not require test copying for additive 
function. 
As an example of the said additive function, the following describes the 
case of applying the color balance control device to the color copying 
machine: 
FIG. 4 is a brief illustration of the flow of the image signal inside the 
color copying machine. The image signals Cin, Min and Yin obtained by 
operating the original in the scanner section 501 are subjected to color 
balance control by the color balance control device 502, and are output as 
Cout, Mout and Yout. Furthermore, after having been subjected to color 
modification or other processing by image processing device 503, these 
signals are fed to printer section 504, where they are output as hard 
copies. In this example, color balance control device 502 is positioned 
immediately after scanner section 501; it may be located immediately 
before printer section 504. 
The input/output signal of color balance control device 502 is CMY density 
signal, and is equivalent to the logarithms of the RGB brightness signal 
used as density signal of the complementary color. Simply reversed 
brightness RGB signal may be used as input and converted into CMY density 
after color balance control. 
FIG. 5 is the block diagram of color balance control device 502 according 
to the present invention. 
The color balance control device 502 comprises operating section 521, 
signal converting means 522, first calculation means 523 and second 
calculation means 524. The operating section 521 produces chromaticity 
signals .alpha., .beta. and .gamma., processing mode signal s, and density 
control signal V. Signals .alpha. and .beta. are converted into color 
balance signal CMY for each color component by a signal conversion means, 
and this signal is fed to first calculation means 523, together with V and 
s. The first calculation means 523 performs operations using these signal 
values to get coefficients RC, RM and RY. The second calculation means 524 
multiplies image signals Cin, Min and Yin by coefficients RC, RM and RY 
before color balance control for each picture element, and produces the 
outputs as image signals Cout and Yout after color balance adjustment. 
FIG. 6 represents an overall view of the color copying machine. 
The machine comprises scanner section 501, image processing section 505 and 
printer section 504. Image processing section 505 contains second 
calculation means 524 as part of the color balance control device 502; it 
also contains the image processing device including color correction 
device, etc. 503. They are composed of multiple electronic devices 
including gate array and memory. 
The operating section 521, signal converting means 522 and first 
calculation means 523 comprises computer 506 having interface with the 
machine, and software. Said computer 506 is equivalent to personal 
computer and work station, and its periphery is provided with color 
display 507, keyboard 508 and mouse 509 to specify the two-dimensional 
coordinates. 
The top of color display 507 is provided with color image 507A, color 
sample 507B and operation menu 507C as illustrated in FIG. 7. 
The color image is displayed in the area shown by 507A. The color image is 
obtained by scanning the color original. Since it has a huge amount of 
picture elements, it is sampled at the pitch of about 1 [picture 
element/mm], and is stored in the image memory (not illustrated) inside 
computer 6. The number of picture elements in this case is about 
297.times.420 picture elements in terms of A3 size paper. 
The color elements stored in the memory are given as CMY density signal, 
and they must be converted into the signal of the RGB which belongs to the 
display system of the color display system, before the color picture 
elements are displayed. In the present embodiment, this conversion is 
performed by software. The signal is firstly reversed, and is then 
subjected to linear masking and other matrix calculation. It is displayed 
on the display unit after having been processed so that the colors of the 
original and color image on the color display will agree approximately 
with each other in standard setting. Said standard setting should be taken 
to mean the state in which density control and color balance control are 
not made. 
Then the colors whose hue and chroma change continuously according to 
coordinates are displayed as color samples on the area 507B on the color 
display. 
The colors to be displayed as color samples are determined by the following 
calculation, when the center of the 507B area is assumed as the origin 
(zero point) and the coordinate value in the horizontal direction is 
assumed as .alpha. and that in the vertical direction as .beta.: 
##EQU1## 
where D.sub.0 is a value representing density. This value cannot be 
specified; it should not be too small or too great because of the problems 
involving ease of reading when displayed on the color display unit, 
precision of calculation, so for the purpose of the present embodiment, 
half the maximum value (D.sub.0 =D.sub.max /2) is used. 
FIG. 5 shows the relationship between the color and position within the 
color samples of the area 507B in the present embodiment. That is, the 
origin .alpha.=.beta.=0 is an achromatic color, and chroma is intensified 
as it goes away from the origin. The hue is changed continuously by the 
angle represented with the origin as an axis. 
The operation menu is displayed in the area 507C on the color display, as 
illustrated in FIG. 9, and is used to operate the color copying machine or 
computer 506. To select the operation, the symbol on color display 507 
should be moved by mouse 509, and should be brought to the position 
(.quadrature., .DELTA. or .gradient.) corresponding to the desired 
operation in the menu and the EXECUTE button installed on mouse 509 should 
be pressed. 
(1) is a copy start switch. Pressing this switch starts copying operation 
at the current setting. 
(2) is a pre-scan switch. Selection of this switch causes the original to 
be coarse scanned, and the image data to be stored in the image memory. 
(3) is a copy style display switch. If this switch is selected, the image 
data obtained by coarse scanning is subjected to such processing as the 
density control and the color balance control. The result is displayed on 
the area A of the display unit as a copy style. 
Selection of (4) switch enables color balance control operation. 
The density is controlled by selecting .increment.(506) or .gradient.(507) 
more than once. In this case, the state of the density control is shown by 
horizontal movement of (505). 
(8) is an additive function selector switch. Selection of this switch 
causes the area 507C to be switched to the different menu. 
(9) is a switch used to disconnect computer 506 from the machine. 
The mode select signal is used to select between conversion of the gray 
into the specified color and conversion of the specified color into gray. 
In the present embodiment, the computer 506 is programmed so that the mode 
select signal is automatically switched according to the symbol position. 
That is, when the EXECUTE button is pressed, computer 506 reads the symbol 
coordinates and determines if it is within the area 507A. If it is within 
the area, the computer produces s=1; otherwise it produces s=0. The result 
is fed to first calculation means 523. 
Firstly, the case of s=1 will be described below: 
Firstly, the program is executed on computer 506. This enables computer 506 
to operate as part of color copying machine. Display as shown in FIG. 7 is 
given on the screen of color display 507. Next, place the original on the 
original mount, and operate mouse 509 to select the pre-scan switch (2) of 
the menu. Then the scanner scans the original in the coarse mode, and the 
image data is stored into the image memory inside computer 506 via the 
interface. Next, when the copy style switch (3) is selected, the color 
image in the image memory is displayed on the color display 507. 
Next, when the color balance switch (4) is selected, the color sample is 
displayed in the area 507. When the entire original is desired to be 
brown, the user should position the symbol to the brown portion inside the 
color sample, and should press the EXECUTE button. This will get him the 
chromaticity signals .alpha. and .beta. and mode signal s=0. The .alpha. 
and .beta. are fed to the signal converting means 522 while s=0 is fed to 
first calculation means 523. 
Signal converting means 522 coverts the chromaticity signals .alpha. and 
.beta. to the CMY color balance signal which is the signal for each color 
component. The CMY color balance signal in this case can be obtained by 
calculation of Formula (1). 
CMY density signals (C.sub.CB M.sub.CB Y.sub.CB) produced from the signal 
converting means 522 are density correction values for color balance 
control for each color component of the specified color, and are supplied 
to the first calculation means 523. 
The first calculation means 523 firstly gets average value .mu.. The .mu. 
can be calculated from Formula (2). 
EQU .mu.=(C.sub.CB +M.sub.CB +Y.sub.CB)/3 (2) 
Next, the ratio between C.sub.CB M.sub.CB Y.sub.CB and .mu. is calculated. 
##EQU2## 
This means that, when there is any achromatic color having density .mu. in 
the original, it is converted into the color represented by C.sub.CB 
M.sub.CB Y.sub.CB. The value RC.sub.CB RM.sub.CB RY.sub.CB calculated in 
this manner is held until color balance is controlled again. 
Next, when the density control switch (6) and (7) are selected, the value 
of density control parameter V changes. The standard set value of the 
density control signal V is V=1.0. The value V is changed every time 
switches (6) and (7) are selected, and the resulting value is maintained. 
Furthermore, in the first calculation means 523, Formula (4) is calculated 
every time color balance control or density control is operated. The final 
coefficient RC RM RY is supplied via the interface to second calculation 
means 524 located in the image processing section on the machine side. 
##EQU3## 
In second calculation means 524, every time coefficient RC RM RY is 
supplied, the values are updated in the register (not illustrated) and 
maintained there. 
Next, when the copy switch is selected, the original is scanned and read, 
and CMY density signals are obtained in the order of the picture element. 
They are assumed to be C.sub.in M.sub.in Y.sub.in. 
Image signals C.sub.in M.sub.in Y.sub.in are fed to second calculation 
means 524, and are output as C.sub.out M.sub.out Y.sub.out after 
calculation of Formula (5). 
##EQU4## 
The output density signals Cout Mout Yout are supplied to image processing 
device including color correction device, etc. 503, and are processed one 
after another. The output is supplied to printer section 504 as color 
materials for cyan, magenta, yellow and black. The color balance 
controlled image is produced from printer section 504. 
A series of these operations enables color balance control so as to obtain 
the color corresponding to the color sample specified on the color display 
507. 
The following describes the case when the color balance is changed so that 
s=1, namely, the specified color will be achromatic color. 
For example, there is a colored photograph original with brownish color all 
over due to discoloration, and it contains a portion which must be 
reproduced in gray. Consider the case of correcting the entire color 
balance by converting that portion into gray. In this case, the user 
should position the symbol 507D to the portion which is to be changed to 
gray inside the color image, and should press the EXECUTE button. The 
.alpha. and .beta. is obtained as color information in this case, and mode 
signal s=1 is output. Mode signal s is supplied to the first calculation 
means 523, so the same processing as in the case of s=0 is performed, 
except for processing in first calculation means 523. 
In first calculation means 523, average value .mu. is obtained by 
calculation of Formula (2) as in the said case. After that, RC.sub.CB 
RM.sub.CB RY.sub.CB is calculated according to Formula 6. 
##EQU5## 
This means that the color represented by C.sub.CB M.sub.CB Y.sub.CB is 
converted into gray having density .mu. in the original. 
The subsequent processing is the same as in the said case of s=1. 
In this manner, if the original contains the scene which should be 
expressed apparently in achromatic color, the color balance control is 
possible by specifying the relevant position. 
The above is the description of an embodiment of applying the color balance 
control device to the color copying machine. It goes without saying that 
the present invention can be applied to all devices requiring color 
balance control without being limited to full color copy and colored 
facsimile. 
As is clear from the above description, the present invention provides the 
color balance device which can be operated also by the users who do not 
know very much about color mixing.