JPH07123281A - Color printer - Google Patents

Abstract

PURPOSE:To obtain a high speed color printer with high resolution having RGB color blend function without increasing the memory capacity. CONSTITUTION:Color data Y1M1C1K1 at an address of a frame memory area 110 of YMCK form corresponding to a position of drawing a picture drawing object are acquired and the data Y1M1C1K1 are inversely converted by using a color conversion circuit 107 inverting color data of YMCK form into color data of RGB form into data R1G1B. Then the color data R1G1B1 and drawn color data R0G0B0 of a picture drawing object are blended by using, e.g. a picture drawing logic blend and resulting data R2G2B2 are converted into data Y2M2C2K2 by using a color conversion circuit 106 converting color data of RGB form into color data of YMCK form into data Y2M2C2K2 and color data of an area of the frame memory area 110 of YMCK form corresponding to a position of drawing picture object are replaced with the data Y2M2C2K2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color printing apparatus for printing a full-color image by using subtractive color mixture.

[0002]

2. Description of the Related Art Conventionally, a color background image (destination)
Overlay the color drawing object (source) on,
The so-called drawing logic is addOver, addPin, subOver, s
ubPin, adMax, adMin, blend, etc. are known. addOver
Is the color closest to the sum of the RGB values of source and destination
When the sum of any of the RGB components exceeds the maximum allowable value, the carry is ignored and the RGB value is obtained by subtracting the maximum allowable value from that value.

AddPin assigns the color closest to the sum of the RGB values of source and destination to destination.
If the sum of any of the RGB components exceeds the maximum allowable value,
The RGB value is that the maximum allowable value is used. subOver assigns the color closest to the difference between the RGB values of source and destination to destination.
If the difference in any of the components is less than "0", the carry is ignored and the RGB value is used as its value minus the maximum allowed value.

SubPin assigns a color closest to the difference between the RGB values of source and destination to destination.
If the difference between any of the RGB components is less than “0”, R
The GB value is that "0" is used. adMax
Is to compare the RGB values of the source and the destination, and to store the value of the RGB component with the higher saturation in the destination. Since the RGB component comparisons are made independently of each other, the resulting color may not be either the source or destination color.

AdMin compares the RGB values of source and destination and dest the value of the RGB component with the smaller saturation.
It is something to put in ination. The RGB components are compared independently, so the resulting color is source or
It may not be one of the destination colors. bl
end is the weighted average of source and destination RGB values
It is replaced with destination and calculated by the following formula.

Destination = source ^* weight + destination ^* (1-weight) Here, weight is a value from “0” to “1”. Originally, these drawing logics were the CR of the host computer.
Since it is based on T color processing, it is created based on RGB format. Therefore, in order to implement this drawing logic in a color printer, it is necessary to have color planes of RGB three colors.

[0007]

However, since the color printer itself expresses colors using subtractive color mixing, unlike CRTs that use additive color mixing, because of the nature of printing on paper, YMC (Yellow, Magenta, cyan)
Alternatively, a full-color image is expressed using YMCK (yellow, magenta, cyan, black) color elements.

Therefore, when the RGB plane is used as the color plane, it also has a YMCK (or YMC) plane at the same time, and once converted, outputs the image to the printing unit, or outputs the image from the RGB to the printing unit. YM
It was necessary to transfer images while converting to CK (or YMC). In the former case, there is a problem that a raster plane of two types of color formats is required and a large amount of memory is required, and in the latter case, RGB 3 colors are used every time data is transferred to each YMCK (or YMC) plane. Since it is necessary to obtain data from the printer and perform color conversion into YMCK (or YMC), there is a problem that the image transfer speed cannot meet the processing speed of the printing device when the printing device has high resolution or high speed. there were.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to realize RGB without increasing the memory capacity.
It is an object of the present invention to provide a high-speed and high-resolution color printing apparatus having the color blending function of.

[0010]

[Means for Solving the Problems] and

In order to achieve the above object, the color printing apparatus of the present invention has the following configuration. That is, a color printing apparatus that prints a full-color image using subtractive color mixture, which converts color data of additive color mixture into color data of subtractive color mixture
Color conversion means, second color conversion means for converting color data of subtractive color mixture to color data of additive color mixture, and color mixing means for creating new color data by mixing two kinds of color data of additive color mixture And mixing the color data of the additive color mixture converted by the second color conversion means and the input color data of the additive color mixture by the color mixing means, and mixing the mixed color data with the first color. It is characterized in that the conversion means performs color conversion and outputs.

Further preferably, the color data of the additive color mixture is RGB data, and the color data of the additive color mixture is YMCK.
It is characterized by being data or YMC data.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the drawings. <First Embodiment> FIG. 1 is a block diagram of a YMCK format full-color printer according to the first embodiment.

In FIG. 1, reference numeral 101 denotes a host computer, which is connected to a control unit 102 of the YMCK full-color printing apparatus indicated by a broken line via a connector (not shown). The control unit 102 is the host computer 1
It is configured to receive a command, data, etc. from 01 and print out. 103 is a CPU, and this is Y
Calculation to control all MCK full-color printers
Take control. A reception buffer 104 temporarily stores received data such as commands and data from the host computer 101. Reference numeral 105 denotes a program ROM, which stores programs and the like for executing a series of controls according to a flowchart shown in FIG. 2 described later. 1
Reference numeral 06 represents a color conversion circuit for converting RGB format color data into YMCK format color data by an algorithm described later, and 107 represents Y by the algorithm described later.
A color conversion circuit for inversely converting MCK format color data into RGB format color data. 108 is a RAM,
The CPU 103 functions as a work area when the program is executed. Further, the RAM 108 includes a drawing logic flag 109 for storing the current drawing logic and a frame memory area 110 for storing the YMCK raster data. An image output unit 111 is a frame memory area 1
YMCK raster data stored in 10
Output to the color laser beam printer 112 which is an MCK color print engine. Further, a power source (not shown) is connected to the control unit 101.

Next, the color conversion circuit 106 and YMCK for converting the RGB format color data into the YMCK format color data.
A color conversion circuit 107 for inversely converting format color data into RGB format color data will be described. When converting color data in the RGB format to color data of the YMC format, assuming a subtractive color ^{_{model, r = Y b -y M b}} -m C b -c g = Y g -y M g -m C g - It can be expressed as ^c b = Y _r ^-y M _r ^-m C _r ^-c .

Taking -log on both sides and summarizing,

[0016]

[Equation 1]

By taking the inverse transformation of the above equation and putting the coefficients together,

[0018]

[Equation 2]

It becomes Here, YMC format data is Y
In order to convert the data into MCK format data, so-called black printing and undercolor removal are performed. These processes are shown by the following formulas. K = k ^* min (Y ', M', C '), 0≤k≤1 Y = Y'-K, M = M'-K, C = C'-K RGB data is converted to YMCK data by the above conversion. Can be converted to.

Further, in order to inversely convert the YMCK data into the RGB data, by the inverse calculation of the above conversion formula, Y '= Y + K, M' = M + K, C '= C + K

[0021]

[Equation 3]

Conversion is performed as R = 10 ^{−log b} , G = 10 ^{−log g} , and B = 10 ^{−log r} . Color conversion circuits 106 and 107
Is a hardware implementation of the above conversion algorithm using a logic circuit. Next, the operation of the color printing apparatus having the configuration of FIG. 1 will be described with reference to the flowchart shown in FIG.

First, when power is supplied to the main body of the color printing apparatus, the process proceeds to step S201, where the current drawing logic flag 109 is set to overWrite (overwrite) drawing logic and YMCK.
Format frame memory area 110 contents to "0" (white)
Initialize to each. Next, in step S202, data is received from the host computer 101, the received data is stored in the reception buffer 104, and one unit code of data is read from the stored reception buffer 104. Then, in step S203, the received data is interpreted as a command, and it is determined whether this is a drawing command, a drawing logic change command, or a paper discharge command, and command branching is performed.

If the drawing logic change command is determined, the process proceeds to step S204, and the specified drawing logic command type (addOver, addPin, subOver, subPin, adMa) is added.
x, adMin, blend, overWrite) is set in the drawing logic flag 109, and the process returns to step S202. On the other hand, if the drawing command is determined in step S203, the process proceeds to step S205, the drawing target object and the drawing color R ₀ G ₀ B ₀ are acquired, and the drawing logic set in the drawing logic flag 109 in step S206. Then YMC
Drawing in the K-format frame area 110, step S20
Return to 2.

On the other hand, if it is determined in step S203 that the instruction is a paper discharge instruction, the flow advances to step S207 to display the contents of the YMCK format frame memory area 110 in the image output unit 11.
The data is sequentially output to the color laser beam printer 112, which is the YMCK color print engine, via 1 and the process returns to step S202. Next, step S206 shown in FIG.
Will be described in detail with reference to the flowchart shown in FIG. 3, taking as an example the case where blend is set in the drawing logic flag 109.

First, in step S301, color data Y ₁ M ₁ C ₁ K ₁ corresponding to the position for drawing a drawing object in the YMCK format frame memory area 110 is acquired. Next, in step S302, this Y ₁ M ₁ C ₁ K ₁
Is inversely converted into R ₁ G ₁ B ₁ by using a color conversion circuit 107 for inversely converting YMCK format color data into RGB format color data. Next, in step S303, this R ₁ G ₁ B
₁ and the drawing color R ₀ G ₀ B _{0 of the} drawing object are mixed by the drawing logic blend. Consequently R ₂ G ₂ B ₂ are determined by _{[R 2 G 2 B 2]} = [R 0 G 0 B 0] * weight + [R 1 G 1 B 1] * (1-weight).

Next, in step S304, this R ₂ G ₂
Using a color conversion circuit 106 that converts B ₂ RGB color data into YMCK color data, Y ₂ M ₂ C ₂ K
_2, and the color data corresponding to the position for drawing the drawing object in the YMCK format frame memory area 110 is replaced with this Y ₂ M ₂ C ₂ K ₂ . If the content of the drawing logic flag 109 is other than blend, step S
The conversion formula of the color mixture of 303 is changed as follows according to each drawing logic.

In the case of addOver, [R ₂ G ₂ B ₂ ] = [R ₀ G ₀ B ₀ ] + [R ₁ G ₁ B ₁ ]> [R _max G _max B _max ]? [R ₀ + R ₁ -R _max G ₀ + G ₁ -G _max B ₀ + B ₁ -B _max ]: [R ₀ + R ₁ G ₀ + G ₁ B ₀ + B ₁ ] In case of addPin, [R ₂ G ₂ B ₂ ] = min ([R ₀ G ₀ B ₀ ] + [R ₁ G ₁ B ₁ ], [R _max G _max B _max ]) In case of subOver, [R ₂ G ₂ B ₂ ] = [ R ₁ G ₁ B ₁ ]-[R ₀ G ₀ B ₀ ] <[R _min G _min B _min ]? [R _min -R ₁ + R ₀ G _min -G ₁ + G ₀ B _min -B ₁ + B ₀ ]: [R ₁ -R ₀ G ₁ -G ₀ B ₁ -B ₀ ] In case of subPin, [R _{2 G 2 B 2] = max} ([R 1 G 1 B 1] - [R 0 G 0 B 0], [R min G min B min]) for _{adMax, [R 2 G 2 B} 2] = max ([R ₁ G ₁ B ₁ ], [R ₀ G ₀ B ₀ ]) In the case of adMin, [R ₂ G ₂ B ₂ ] = min ([R ₁ G ₁ B ₁ ], [R ₀ G ₀ B ₀ ]) In the case of overWrite, [R ₂ G ₂ B ₂ ] = [R ₀ G ₀ B ₀ ] <Second Embodiment> FIG. 4 is a block diagram of a YMC format full-color printing apparatus in the second embodiment.

In FIG. 4, reference numeral 401 denotes a host computer, which is connected to a control unit 402 of the YMC full-color printing device indicated by a broken line via a connector (not shown). The control unit 402 is the host computer 40
It is configured to receive a command, data, etc. from 1 and print out. 403 is a CPU, and this YM
C Performs calculations and controls to control the full-color printing device. A reception buffer 404 temporarily stores reception data such as commands and data from the host computer 401. A program ROM 405 stores programs and the like for executing a series of controls according to the flowchart of FIG. 5 described later. Reference numeral 406 represents YM color data in RGB format according to an algorithm described later.
407 is a color conversion circuit for converting into C format color data.
Is a color conversion circuit for inversely converting YMC format color data into RGB format color data by an algorithm described later. A RAM 408 functions as a work area when the CPU 403 executes the program. Also, R
The AM 408 includes a drawing logic flag 409 for storing the current drawing logic and a frame memory area 410 for storing the YMC raster data. An image output unit 411 is a YMC stored in the frame memory area 410.
Data are sequentially printed in YMC color printing engine,
Output to the laser beam printer 412. Furthermore, a power source (not shown) is connected to the control unit 401.

Next, a color conversion circuit 406 for converting RGB format color data into YMC format color data and a color conversion circuit 407 for inverse conversion of YMC format color data into RGB format color data will be described. When converting color data in the RGB format to color data of the YMC format, assuming a subtractive color ^{_{model, r = Y b -y M b}} -m c b -c g = Y g -y M g -m c g - It can be expressed as ^c b = Y _r ^-y M _r ^-m _cr ^-c .

Taking -log on both sides of this equation and summarizing,

[0032]

[Equation 4]

Taking the inverse transformation of the above equation and putting the coefficients together,

[0034]

[Equation 5]

[0035] By the above conversion, RGB data can be converted into YMC data. Further, in order to inversely convert the YMC data into RGB data, by the inverse calculation of the above conversion formula,

[0036]

[Equation 6]

Conversion is performed as R = 10 ^{−log b} , G = 10 ^{−log g} , and B = 10 ^{−log r} . Color conversion circuits 406 and 407
Is a hardware implementation of the above conversion algorithm using a logic circuit. Next, the operation of the color printing apparatus having the configuration of FIG. 4 will be described with reference to the flowchart shown in FIG.

First, when power is supplied to the main body of the color printing apparatus, the process advances to step S501 to set the current drawing logic flag 409 to the overWrite drawing logic and set the contents of the YMC format frame memory area 410 to "0". Initialize each to (white). Next, in step S502, data is received from the host computer 401, the received data is stored in the reception buffer 404, and one unit code of data is read from the stored reception buffer 404.
Then, in step S503, the received data is interpreted as a command, and it is determined whether this is a drawing command, a drawing logic setting command, or a paper discharge command, and command branching is performed.

If it is determined that the command is a drawing logic setting command, the flow advances to step S504 to proceed to the specified drawing logic command type (addOver, addPin, subOver, subPin, adMa).
x, adMin, blend, overWrite) is set in the drawing logic flag 409, and the process returns to step S502. On the other hand, if the drawing command is determined in step S503, the process proceeds to step S505, the drawing target object and the drawing color R ₀ G ₀ B ₀ are acquired, and the drawing logic flag 409 set in step S506. Then YMC
Draw in the frame area 410 of the format, and step S502
Return to.

On the other hand, if it is determined in step S503 that a paper discharge command has been issued, the contents of the YMC format frame memory area 410 are sequentially output through the image output unit 411 to the color laser beam, which is the YMC color print engine, in step S507. -Output to the printer 412, step S502
Return to. Next, the details of step S506 shown in FIG.
A case where blend is set in the drawing logic flag 409 will be described as an example according to the flowchart shown in FIG.

First, in step S601, color data Y ₁ M ₁ C ₁ corresponding to a position for drawing a drawing object in the YMC format frame memory area 610 is acquired. Next, in step S602, the Y ₁ M ₁ C ₁ is inversely converted into R ₁ G ₁ B ₁ by using a color conversion circuit 407 which inversely converts YMC format color data into RGB format color data. Next, in step S603, the R ₁ G ₁ B ₁ and the drawing color R ₀ G ₀ B _{0 of the} drawing object are mixed by the drawing logic blend. Consequently R ₂ G ₂ B ₂ are determined by _{[R 2 G 2 B 2]} = [R 0 G 0 B 0] * weight + [R 1 G 1 B 1] * (1-weight).

Next, in step S604, this R ₂ G ₂
B ₂ is converted into Y ₂ M ₂ C ₂ using a color conversion circuit 406 that converts RGB format color data into YMC format color data, and this Y ₂ M ₂ C ₂ is used to convert the YMC frame memory area 410. Replace the color data corresponding to the drawing position of the drawing object. When the content of the drawing logic flag 409 is other than blend, the color mixing conversion formula in step S603 is changed as follows according to each drawing logic.

In the case of addOver, [R ₂ G ₂ B ₂ ] = [R ₀ G ₀ B ₀ ] + [R ₁ G ₁ B ₁ ]> [R _max G _max B _max ]? [R ₀ + R ₁ -R _max G ₀ + G ₁ -G _max B ₀ + B ₁ -B _max ]: [R ₀ + R ₁ G ₀ + G ₁ B ₀ + B ₁ ] In case of addPin, [R ₂ G ₂ B ₂ ] = min ([R ₀ G ₀ B ₀ ] + [R ₁ G ₁ B ₁ ], [R _max G _max B _max ]) In case of subOver, [R ₂ G ₂ B ₂ ] = [ R ₁ G ₁ B ₁ ]-[R ₀ G ₀ B ₀ ] <[R _min G _min B _min ]? [R _min -R ₁ + R ₀ G _min -G ₁ + G ₀ B _min -B ₁ + B ₀ ]: [R ₁ -R ₀ G ₁ -G ₀ B ₁ -B ₀ ] In case of subPin, [R _{2 G 2 B 2] = max} ([R 1 G 1 B 1] - [R 0 G 0 B 0], [R min G min B min]) for _{adMax, [R 2 G 2 B} 2] = max ([R ₁ G ₁ B ₁ ], [R ₀ G ₀ B ₀ ]) In the case of adMin, [R ₂ G ₂ B ₂ ] = min ([R ₁ G ₁ B ₁ ], [R ₀ G ₀ B ₀ ]) In the case of overWrite, [R ₂ G ₂ B ₂ ] = [R ₀ G ₀ B ₀ ] As described above, according to the first and second embodiments, R
Y for drawing data having color data input in GB format
When writing to MCK or YMC format raster memory,
RGB obtained by acquiring YMCK or YMC data stored in advance in the drawing position of the drawing data on the raster memory and converting from YMCK or YMC format to RGB format
The data and the color data input in the RGB format of the drawing data are mixed to obtain new RGB data, and the obtained RGB
By converting the data from the RGB format to the YMCK or YMC format and writing the data at the drawing position of the drawing data on the raster memory, the YMCK or YMC format full-color printing apparatus does not have an RGB raster plane and saves memory. Moreover, there is an effect that a color blending function of RGB (various color drawing logics) can be realized at high speed.

In the first and second embodiments, the color laser printer is used as the print output device, but a color ink jet printer, a color thermal transfer printer (including a sublimation type), a color silver salt printer, etc. , YMC or YMCK format color printing apparatus may be applied to any type of printing apparatus. In addition, in the first and second embodiments, RGB ← → YMC or RGB ← → Y
Although the color conversion of MCK is realized by using a hardware circuit, it may be performed by software. On the contrary, in the first and second embodiments, addOver, addPin, subOver, subPin, adMa
Although logic drawing such as x, adMin, blend, and overWrite is realized by using software, it may be realized by a hardware logic circuit, which has an advantage that it can be executed at higher speed. Furthermore, RGB ← → YMC or RGB ← → Y
MCK color conversion circuit and addOver, addPin, subOver, subPin,
By combining with logic drawing circuits such as adMax, adMin, blend, and overWrite, it becomes possible to execute at higher speed.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Further, it goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0046]

As described above, according to the present invention,
It is possible to provide a high-speed and high-resolution color printing device having an RGB color blending function without increasing the memory capacity.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of a YMCK color printer according to a first embodiment.

FIG. 2 is a flowchart showing control in a YMCK format color printing apparatus.

FIG. 3 is a flowchart showing details of an algorithm of a drawing logic unit.

FIG. 4 is a schematic block diagram showing a configuration of a YMC format color printing apparatus in a second embodiment.

FIG. 5 is a flowchart showing control in a YMC color printer.

FIG. 6 is a flowchart showing details of an algorithm of a drawing logic unit.

[Explanation of symbols]

 101 Host Computer 102 Control Unit of YMCK Full Color Printer 103 CPU 104 Reception Buffer 105 Program ROM 106 RGB → YMCK Color Conversion Circuit 107 YMCK → RGB Color Conversion Circuit 108 RAM 109 YMCK Frame Memory Area 110 Drawing Logic Flag 111 Image Output Section 112 YMCK Method Color laser printer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 11/00 H04N 1/46 9192-5L G06F 15/72 310 4226-5C H04N 1/46 Z

Claims (2)

[Claims] 1. A color printing apparatus for printing a full-color image using subtractive color mixing, comprising: first color conversion means for converting color data of the additive color mixture into color data of the subtractive color mixture; and color data of the subtractive color mixture. The second color conversion means includes a second color conversion means for converting color data of additive color mixture and a color mixing means for mixing two kinds of color data of additive color mixture to create new color data. The converted color data of the additive color mixture and the input color data of the additive color mixture are mixed by the color mixing means, and the mixed color data is converted by the first color conversion means and output. And color printing equipment. 2. The color printing apparatus according to claim 1, wherein the color data of the additive color mixture is RGB data, and the color data of the additive color mixture is YMCK data or YMC data.