JP3066898B2 - Color image forming equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image processing apparatus that develops image information expressed in a page description language in a memory and performs color processing.

[Conventional technology]

Conventionally, PDL (Page Description La
A device for forming an image by using data as input data has mainly been a color graphic display. PDL is a language for describing output data of page layout software. As shown in FIG. 3, image description by character code, image description by graphic code, and image description by bit data are handled by page layout software. Describe the desired image in combination. The graphic display which uses PDL data as input data usually has three bit map memories of red (R), green (G) and blue (B), and each bit map memory according to the color information of the PDL data. The image data designated by the image description using character codes, the image description using graphic codes, and the image description using bit data are developed and displayed. In addition,
A color image used in a computer is often separated into three color components of R, G, and B, and a PD containing color information is generally used.
L handles color information by three color components of R, G, and B.

For this reason, a color printer that uses PDL data including color information as input data has three RGB bit map memories, similar to the graphic display described above, and forms an image using three RGB color components. Conceivable.

[Problems to be solved by the invention]

However, general color printers use subtractive color components for mixing color materials, for example, cyan, magenta,
An image is formed in yellow, and red, green and blue, which are additive color systems, cannot be used and conversion must be performed.

Furthermore, for high-resolution, multi-tone color printers,
When the image forming method for the display is applied, the amount of memory becomes large for the following two reasons.

1) For display, it would have been nice if there were 3 sets of RGB bitmap memory.
To obtain a high-quality image, a black component is required in addition to cyan, magenta, and yellow components. To obtain a higher-gradation image, each component must have 6 to 8 bits of data. Instead, the amount of memory required per pixel increases.

2) The resolution of a high-resolution printer is 400 dpi (dotpar inc
h), the number of pixels constituting an image is larger than that of a graphic display of about 70 dpi.

Therefore, for example, 400 dpi, the color material is four colors of yellow, magenta, cyan, and black.
With an 8-bit color printer, about 64MByte of memory is required to make up the A4 bit map memory. The necessity of such a large amount of memory has been one problem for developing a color image forming apparatus (for example, a color printer) using PDL data as input data.

SUMMARY OF THE INVENTION It is an object of the present invention to develop image information represented by a page description language with a small-capacity memory and perform color processing.

[Means for solving the problem]

In order to achieve the above object, the color image processing apparatus of the present invention uses image development control information (for example, FIG. 15B-2 of FIG. 15B-2, 15B-3 of FIG.
(C) FIG. 15c-2, FIG. 7 (d) corresponding to FIGS. 15d-2 to 7) and color data (similarly, FIG.
input means for inputting image information including (b-1), (c) FIG. 15c-1 and (d) FIG. 15d-1 (similarly, to the external interface circuit 2 in FIG. 1 of the present application). Storage means for storing a correspondence relationship between the color data composed of a plurality of color components and code data having a smaller data amount than the color data (also corresponding to FIG. 4 of the present application); The color data composed of the plurality of color components included in the image information is converted into code data based on the correspondence relationship, and the image data is expanded in a memory using the code data based on the image expansion control information. Raster processing means to generate the raster data shown (similarly,
The CPU reads out the raster data indicated by the code data expanded in the memory in synchronization with the image formation of the image forming unit, and performs color processing according to the output characteristics of the image forming unit. And a color processing unit (similarly, corresponding to the image processing circuit 33 in FIG. 1 of the present application) for outputting to the image forming unit.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a block diagram of a color printer according to the present embodiment. Reference numeral 23 denotes a general-purpose digital interface such as an RS232C interface or a Centronics interface, and reference numeral 2 denotes an interface circuit for these. 24 is a CPU bus including an address bus and a data bus.
sing Unit) 5, ROM (Read Only Memory) 6, RAM (Ramdom
Access Memory) 7, DMAC (Direct Memory Access Control)
ller) 8, a control I / O port 9, a font ROM 31, a PDL data memory 3, and a full-page image memory 4 are connected to enable data transfer and control by the CPU 5 during this period. ROM6 is
ROM for holding the program of CPU5, RAM7 is C
Work RAM for PU5. The CPU 5 communicates with an external host device via the external interface circuit 2 to exchange various commands, statuses, and image data. When receiving the transfer command of the PDL data among the commands, the CPU 5 operates the DMAL 8 and transfers the PDL data transferred via the external interface circuit 2 to the PDL data memory 3 by DMA (Direct Memory Access). D
MA transfer is a data transfer method used in general microcomputer systems. When the transfer of all the PDL data is completed, the CPU 5 first clears the full page image memory 4. Here, clearing the memory means writing a value that prevents an image from being formed during image formation, which will be described later, in the memory. In the case of the present embodiment, such a value is written by the CPU 5, but it is also possible to write in a hardware manner with a simple circuit consisting of a clock generator and a counter. The full page image memory 4 is a so-called bit map memory, and can set a palette data value for each pixel. The palette data value is data representing a color number, and each palette data value is associated with a specific color. For example, as shown in FIG. 4, when the palette data value is 0, it is associated with white, when it is 1, yellow, and 2 is associated with magenta. This association differs depending on the color printer, and can be made variable by a command from the host device even in one color printer. In the color printer of this embodiment, the palette data values are associated with the colors represented by the values as shown in the table of FIG. In the figure, R component data, G component data, and B component data represent the color represented by each palette data value by using NTSC RGB luminance values.

After clearing the memory, the CPU next interprets the PDL data held in the PDL data memory, and expands the specified image in the full page image memory. At this time, the data is written to the memory using palette data corresponding to the color closest to the color information indicated by the PDL data. This expansion method will be described later in detail. The full page memory 4 can perform both data write and read access by the CPU path and read access by the address generated by the address generation unit 12. The full page memory 4 uses the control signal 25 from the control I / O port 9. To switch. The above-described image development is performed on the access side by the CPU bus. When the development to the full page image memory is completed, the CPU 5 switches the access to the full page memory to the address generation unit side. The pallet data 26 read from the full page image memory according to the address generated by the address generator is input to the pallet data conversion circuit 35,
Then, it is converted into RGB component data 32-1, 32-2, 32-3. The RGB component data is input to the image processing circuit 33, where one output color component data is calculated, and the image forming signal V
_OUT 27. The reading of the pallet data from the full page image memory, the conversion of the pallet data to RGB component data, and the calculation of the image forming signal are performed for each of four image formations described later.
The magenta component image, the cyan component image, and the black component image are output as the image forming signal V _OUT 27. Image processing circuit
The output of 33 is input to the laser driver 10 by the tone control circuit 34, the data of which the tone is corrected by a LUT (LOOK UP TABLE) or the like so as to correspond to the color reproduction density of the printer. The formation takes place.

The CPU 5 calculates one output color component data by performing image processing on the red component image data, the green component image data, and the blue component image data developed in each full page image memory in this manner, and The process of forming
By repeating for each output color component of yellow, magenta, cyan, and black, a full-color image is formed.

The CPU 5 controls each control element of the color printer 1 via a control I / O port in addition to communication with an external device.
Reference numeral 15 denotes a potential sensor for detecting the electric charge charged on the photoconductor 16, and reference numeral 14 denotes a potential measurement unit that converts an output from the potential sensor 15 into a digital signal and inputs the digital signal to the control I / O port 9. The potential data input to the control I / O port 9 is read by the CPU 5 and used for control. The drive motor 20 is used to drive each drive element of a color printer such as a transfer drum.

On the other hand, a signal 30 from the image leading end detection sensor 18 is input to the control I / O port 9 and read by the CPU 5,
It is used to create a vertical synchronization signal (ITOP) 29 to be given to the address generator 12.

A signal 28 from a BD (beam detector) detector 13 is given to the address generator 12 as a horizontal synchronization signal (HSYNC).

The outputs of the humidity sensor 21 and the temperature sensor 22 for correcting the development characteristics are input to the control unit I / O port 9 via the A / D changing unit 19.

FIG. 2 is a configuration diagram of the color printer of the present embodiment.
The output color component images of yellow, magenta, cyan, and black developed in the full-page image memory 4 are subjected to PWM processing and the like by the laser driver 10 every four image formations, and finally the laser 11 Drive.

The laser light modulated in accordance with the image data is scanned at high speed by a polygon mirror 99 rotating at high speed, and is reflected by the mirror 90 to perform dot exposure corresponding to the image on the surface of the photosensitive drum 91. One horizontal scan of the laser beam corresponds to one horizontal scan of the image, and has a width of 1/16 mm in this embodiment. On the other hand, since the photosensitive drum 91 is rotating at a constant speed in the direction of the arrow, a plane image is successively exposed by the above-described laser beam scanning in the main scanning direction and the constant speed rotation of the photosensitive drum 91 in the sub-scanning direction. The photosensitive drum 91 is uniformly charged by the charger 97 prior to exposure, and forms a latent image by exposing the charged photoconductor to light. A latent image based on a predetermined color signal is visualized by developing units 92 to 95 corresponding to a predetermined color.

For example, considering the first image formation in which a yellow component signal is output from the full page image memory 4, first, a dot image of the yellow component of the document is exposed on the photosensitive drum 91 and is developed by the yellow developing unit 92. .

Next, the yellow image is transferred and formed on the paper wound on the transfer drum 96 by the transfer charger 98 at the contact point between the photosensitive drum 91 and the transfer drum 96. In the same process as above, in the second, third and fourth image formation, the magenta, cyan and black components are output from the full page image memory 4 according to the magenta, cyan and black component signals, respectively. The toner images are repeatedly transferred and formed, and the respective images are superimposed on the paper to form a color image using four color toners.

FIG. 3 is a diagram for explaining a method of realizing the address generator 12 of FIG. 1 in the present embodiment. Reference numeral 200 denotes an image clock generator which generates an image transfer clock. The counter 202 is cleared by the horizontal synchronizing signal (HSYNC) 28, and generates a horizontal address 205 by counting the transport clock 203. On the other hand, the counter 201 is cleared by the vertical synchronizing signal (ITOP) 29 and generates a vertical address 204 by counting the horizontal synchronizing signal (HSYNC). Using the horizontal address as the lower address and the vertical address as the upper address, the address of the full page image memory
Make up 26. When the full-page image memory is used with such an address configuration, the image must be expanded in accordance with this address allocation even when the image is expanded to the full-page image memory by the CPU before this.
For example, image data at a point where the horizontal address is X and the vertical address is Y must be written to an address where the upper address is Y and the lower address is X in the full page image memory.

FIG. 4 is a correspondence table of the palette data 26, which is the input of the palette data conversion circuit 35, and the R component image data 32-1, G component image data 32-2, and B component image data 32-3, which are outputs. In this embodiment, the palette data is represented by 8 bits.
It has a value from 0 to 255. On the other hand, each color component data is also represented by 8 bits and has a value of 0 to 255, respectively. The pallet data conversion circuit 35 uses the pallet data as an address and holds a LUT (LOOK UP) for holding each color component data at a corresponding address.
TABLE).

For example, with respect to the palette data 0, the value 255 may be written to the address 0 of the L component data LUT, 255 to the address 0 of the G component data LUT, and 255 to the address 0 of the B component data LUT. .

FIG. 5 is a block diagram of the image processing circuit 33. Each color component signal inputted VB26-3, VG26-2, VR26-1 are input to the logarithmic conversion LUT, is converted from the luminance data of BGR density data Y _1, M _1, C ₁ of YMC. At this point, these data correspond to the toner density values of yellow, magenta, and cyan in the output image, the output for R (red) is the toner amount for C (cyan), and the output for G (green) is Output for toner amount of M (magenta) and B (blue) is Y (yellow)
, The subsequent color image data is treated as YMC color components.

The output of the logarithmic conversion LUT312~314 calculates a K ₁ of a minimum value calculating circuit _{315 K 1 = MIN (Y 1} , M 1, C 1). K ₁ is the minimum value among Y ₁ , M ₁ , and C ₁ . The K ₁ becomes Moto calculating the corner corners amount when performing (black) insertion (black toner amount), and, Moto calculating the weight loss (UCR) amounts of other color component toner with the inking become. K ₁ is first in the circuit 317 Y = cx-d (c , d are constants)
Is converted to black component data K ₂ 343, and selector 3
Put in 25. Further, V _K is equal to Y = ax in circuit 316.
After the conversion of −b (a and b are constants), the UCR amount 332 is obtained. The UCR circuits 318 to 320 subtract the UCR amount 332 from the YMC color component data Y ₁ , M ₁ , and C ₁ to calculate Y ₂ , M ₂ , and C ₂ , respectively. The relationships among Y ₂ , M ₂ , C ₂ , K ₂ , V _B , V _G , and V _R can be summarized as follows.

K ₁ = MIN (LG (VB), LG (VG), LG (VR)) (LG indicates a logarithm) K ₂ = c × K ₁ −d (c and d are constants) Y ₂ = LG (V _{B ) - (a × K 1 -b} ) (a, b are _{constants) M 2 = LG (V G} ) - (a × K 1 -b) C 2 = LG (U R) - (a × K 1 -b Next, the outputs Y ₂ , M ₂ , and C ₂ of the UCR circuit are subjected to masking correction for performing color correction by the following linear expression.

This type of masking correction is a general correction performed because the toner as a color material does not have ideal color characteristics.

 In the circuit shown in FIG. 4, this correction is performed as follows.

First, aY ₁ , −bM ₁ , −c
Nine parameters such as C ₂ and −aY ₂ are set. These parameters enter the selector 310 and are selected in groups of three according to which of Y ₃ , M ₃ , and C ₃ is to be calculated. That is, Y ₃
When calculating, aY ₁ , −bM ₁ , −cC ₁ is selected, when calculating M ₃ , −aY ₂ , bM ₂ , −cC ₂ is selected, and when calculating C ₃ , − aY ₃ , −bM ₃ and cC ₃ are selected. This selection is based on the output color component selection signal C ₀ , which is set on the latch 309 by the CPU bus.
Performed by C _1, parameters as C _0, C ₁ is the time Y ₃ (0,0), is when M ₃ (0,1), are calculated C ₃ when the (1,0) Is selected. The selected parameters are multipliers 321-323
Is multiplied by each of the color component data Y ₂ , M ₂ , and C ₂ , and the result is added by the adder 324 to enter the selector 325.

The selector 325 selects the black component data K ₂ when the output color component selection signals C ₀ and C ₁ are (1, 1), and otherwise selects the adder 324.
Select the output of As a result, when the output color component signals C ₀ and C ₁ are (0,0), a masking-corrected yellow component image is output as the image forming signal V _OUT 27, and when the output color component signals C ₀ and C ₁ are (0,1), the same applies. In the case of (1,0), a cyan component image is output, and in the case of (1,1), a black component image is output.

FIG. 6A shows a vertical synchronizing signal (ITOP) 29 and a horizontal synchronizing signal (HSYNC) 28 input to the address generator when four image formations are performed, and a full page generated by the address generator. The upper address 204 of the image memory 4, the palette data 26 read from the full page image memory, and the RGB color component signals 32-1, 32-2, 32-3 generated therefrom by the palette data conversion circuit 35. Image forming signal V _OUT 27 generated by image processing circuit 33
This is a timing chart. As shown in the figure, yellow component data, magenta component data, cyan component data, and black component data are produced following each vertical synchronizing signal, and are sent to the laser driver 10. In the figure, the upper address is written so as to change continuously for the sake of clarity. However, since it is actually the output value of the counter which receives the HSYNC signal, the upper address has a step-like shape synchronized with HSYNC. Sixth
FIG. 6B is a timing chart of each signal in the section shown in FIG. 6A. This timing chart is for a section from one horizontal synchronization signal (HSYNC) 28 to the next horizontal synchronization signal, and indicates the timing of each signal in one horizontal section. The upper address 204 is counted up by one for each HSYNC. Lower address 205 is H
It becomes 0 at SYNC, and is counted up one by one at the image carrying clock 203. Since the data of the address specified by the lower address 205 and the upper address 204 in the full page image memory 4 is read and becomes the pallet data 26,
Upper address n + ₁ P 1 ~P ₈ of the 6 (b) in the figure, respectively,
It is data of lower addresses 0 to 7, and P ₁ 'to
P ₈ ′ is the upper address n + 2 and the lower addresses 0 to 7
Address data. That is, P _{1 to} P ₈ are P ₁ ′
Image data at a position vertically displaced from P ₈ ′ by one. This is the value of R _1-
For R ₈ , R ₁ ′ to R ₈ ′ and G _{1 to} G ₈ , G ₁ ′ to G ₈ ′,
The same applies to B _{1 to} B ₈ and B ₁ ′ to B ₈ ′, and similarly to the finally calculated image forming signals Y _{1 to} Y ₈ . Thus, R _{1 to} R ₈ , G _{1 to} G ₈ , B _{1 to} B ₈ , Y _{1 to} Y ₈ are P _{1 to} P ₈
It corresponds to. The pallet data 26 is processed by a pallet data conversion circuit to become respective color component signals 26-1, 26-2, 26-3, and further processed by an image processing circuit 33 to form an image forming signal.
27, a time delay occurs between these signals, but in FIG. 6, this difference is set to 0 for the sake of explanation.

7 (a) to 7 (e) show PDL (Page Description La)
FIG. What is PDL?
As shown in FIG. 7A, a general term for a language for describing one or more images by combining an image description using character codes, an image description using graphic codes, and an image description using bit data. is there. PDLs which are considered to be influential today include PostScript (Adobe Systems), DDL
(Imagen, Hewlett Packard) and Interpress (XEROX).

In the description of this example, a simple PDL shown in FIGS. 7B to 7D will be used.

FIG. 7B is an example of an image description using character codes.
First, at l5b-1, an instruction is given to perform the subsequent character description in a color in which all the red (R), green (G), and blue (B) luminance data are 0, that is, black. Next, in l5b-2, the character string "IC" is assigned to a variable called String, and in l5b-3, it is shifted from the origin (upper left corner) to the right to the maximum value of the horizontal coordinate (hereinafter referred to as XMAX) X0, below. The maximum value of vertical coordinates (hereinafter YMA
X), that is, X0, ie, width XMAX × 0.3, height YMA from the upper left corner
An instruction to print the contents of a String is given by X × 0.3 and character spacing XMAX × 0.1.

FIG. 7 (c) is an example of image description using graphic codes.
First, in l5c-1, luminance data of red (R), green (G), and blue (B) is represented by 1.0, 0.0, 0.
The instruction to perform with the color 0, that is, red, is given. Next, l5c-2
The horizontal coordinate is XMAX x 0.0 and the vertical coordinate is YMAX x 0.
From point 4 the horizontal coordinate is XMAX x 1.0 and the vertical coordinate is YMA
The user is instructed to draw a straight line up to the point of X × 0.4.

FIG. 7D is an example of an image description using bit data. First, in l5d-1, the following bit data is converted into red (R), green (G), and blue (B) luminance data, respectively.
Instructions are given with colors 1.0, 1.0, 0.5, that is, light yellow.

Next, in l5d-2 to l5d-6, 25 pieces of bit data are substituted for the variable bit.data, and in l5d-7, it is set based on the point of the horizontal coordinate XMAX × 0.1 and the vertical coordinate YMAX × 0.5. , From the horizontal size to a bit size of 5 in the vertical direction.

FIG. 7 (e) shows an example in which the image descriptions shown in FIGS. 7 (b) to 7 (c) are developed for an image forming apparatus having XMAX = 10 and YMAX = 10.

First, according to the description using the character code shown in FIG.
A red line is created in the center by the description by the graphic code shown in FIG. 7C, and a light yellow diamond is made at the bottom by the description by the bit data shown in FIG. 7D.

(Control by CPU) FIGS. 8A and 8B are flow charts for explaining the control by the CPU 5. FIG. First, in step SP101,
It is checked whether a command has been sent from an external host device, and if so, the process is branched for each command in step SP102 and the processing is performed. When a status request command is issued,
Return the status to the host device in SP103 and step SP101
Return to In the case of a PDL data transfer command, step SP105
In step SP113, the PDL data is received, an image is formed based on the PDL data, and the process returns to step SP101. In the case of other commands, processing corresponding to each command is performed in step SP104, and the process returns to step SP101. At the time of the PDL data transfer command, first, in step SP105, PDL data is received from an external host device, and the received PDL data is stored in the PDL data memory. This transfer can be done by CPU5,
As described above, in this embodiment, the transfer is performed by DMA transfer by the DMAC.

Next, in step SP106, the PDL data in the PDL data memory is interpreted, and the designated image is developed on the full page image memory 4.

Next, in step 107, the full page image memories 4-1, 4
-2,4-3 access is switched to the address generator,
The read palette data is converted into R, G, B component data, and further, an image processing circuit 33 calculates a yellow image signal therefrom, thereby forming a yellow image. In steps SP108 to SP110, a magenta image, a cyan image,
A black image is formed, and in step SP111, each color component toner on the paper is fixed and discharged outside the apparatus. Next, in step SP112, it is checked whether or not the set number of color images has been formed in steps SP107 to SP111, and if not completed, the flow returns to step SP107.

On the other hand, if the process has been completed, the process returns to step SP101 to end the process of image development and formation.

8 (b) according to the flowchart of FIG.
(A) Step SP106 in the figure will be described in detail.

In step SP201, the full-page image memory is cleared so that an image is not formed except for the portion where the image has been developed later. More specifically, in step SP202 of writing palette data 0 (white) over the entire surface, initialization is performed on a variable ccolor representing a character color, a variable gcolor representing a graphic color, and a variable bcolor representing a bit data color. These are represented by a set of three luminance data of red (R), green (G), and blue (B).

Next, in steps SP203 to SP216, the development of one line of PDL data is performed, and the PDL data of all lines in the PDL data memory is expanded.
Repeat for DL data. Step SP217 is P for all lines
This is a check whether the DL data has been expanded.

First, at step SP203, one line is read from the PDL data memory, and then branching is performed according to the type of PDL data read at step SP204.

In the case of the character color setting (15b-1 in the example of FIG. 7), the ccolor is reset in step SP205. At the time of setting the graphic color (15c-1 in the example of FIG. 7), gcolor is set in step SP206.
To reset. Bit data color setting (in the example of FIG. 5,
In the case of l5d-1), bcolor is reset in step SP207. At the time of character string substitution (15b-2 in the example of FIG. 7), the variables and their contents are related by a table or the like set on the work RAM 7 in step SP208. When bit data is substituted (15d-2 to 6 in the example of FIG. 7), step SP209 is performed.
Similarly associates the variable with its contents.

When character development of (in the example of FIG. 7 L5b-3), first calculates the Paretsutodeta values P _OUT from ccolor at step SP210. Red, green, and blue component values of ccolor are Rin, Gi
If n, Bin (0 <Rin <1,0 <Gin <1,0 <Bin <1),
The CPU 5 searches the table on the ROM 6 expressing the relationship between the palette data and each color component data shown in FIG. 4, and finds the palette data corresponding to the above-mentioned pair of Rin, Gin, Bin. This table may be created on the RAM 7, in which case the table can be rewritten by the CPU 5.

In this search, the following distances are sequentially calculated for each palette data Pi, and the smallest palette data may be found. Here, Ri, Gi, Bi are color component data corresponding to the palette data Pi.

dl = | Ri−255 × Rin | ² + | Gi−255 × Gin | ² + | Bi−255 × Bin | ² In addition, a certain regularity is given to the array of the palette data, and the palette data value is set to Rin. , Gin, and Bin.

For example, if Pi = (Rin% 0.13) × 32 + (Gin% 0.13) × 4 + (Bin% 0.26) (% is a function for obtaining an integer quotient), each Rin, Gin, Bin is not less than 0 and not more than (Rin %
(0.13) and (Gin% 0.13) take any value from 0 to 7, and (Bin% 0.26) takes any value from 0 to 3. Therefore, Pi takes a value of 0 to 255 (7 × 32 + 7 × 4 + 3).

Next, in step SP211 the font pattern corresponding to the character code is read from the font ROM 31 and the step SP211 is executed.
At 12, the image is developed on the full page image memory 4. At this time, P _OUT is used as data to be written. At this time, enlargement or reduction is performed to the designated size. However, it is easy to perform this in a software manner and will not be described.

Next, at the time of graphic development (15c-2 in the example of FIG. 7),
First, gcolor in step SP213 as in step SP210
, The pallet data value P _OUT is calculated, and in step SP214, a figure is written on the full page image memory 4 using this value P _OUT . Algorithms for drawing designated graphics, for example, lines, circles, and ellipses, by software are generally known and will not be described here.

Next, bit image development (in the example of FIG. 7, l5d-
7) When the first at step SP215 in the same manner as step SP210 to calculate the Paretsutodeta values P _OUT from bcolor, on the full-page image memory 4 at step SP216, the value P _OUT
Write bit data using.

At the time of image development in steps SP212, SP214, and SP216, the horizontal coordinate value is set to the lower address,
Address calculation is performed using the vertical coordinate value as the upper address.

Thus, the image indicated by the input PDL data can be developed on the full page image memory 4 by the control flow shown in FIG. 8 (b).

[Other embodiments]

In the above embodiment, all the image development is performed by software. However, a part of the image development, such as font development, may be replaced by hardware.

Further, in the above-described embodiment, the image forming unit is an electrophotographic color printer, but may be a thermal transfer system, a silver halide system, an electrostatic system, or the like. Also, a so-called 4D system having a latent image drum for each formed color may be used.

Further, in the above-described embodiment, the general-purpose interface (interface circuit shown in FIG. 1) such as GPIB or RS232C is used as input means. However, this may be a CPU bus such as a VME bus, and further, a magnetic tape, a magnetic disk, or the like. Or an off-line media such as Ethernet, or a LAN such as Ethernet. In this embodiment, the means for converting the color information into the color numbers is the CPU 5 which converts the color information into the color numbers as shown in FIG.

In the above embodiment, the image storage unit is the full page image memory 4 and a bit map memory having the same resolution as that of the image forming apparatus is used. However, an enlargement process may be performed at the time of image formation using a smaller frame memory. Although the image developing means of the present invention is the SP 106 in FIG. 8A, that is, the CPU 5 executing the flow in FIG. 8B, this may be performed by hardware as described above.

As described above, according to the present embodiment, the input PD
The color information of the L data is converted into a printer-specific color number, and the image is developed on the frame memory using the color number. At the time of image formation, the color number read from the frame memory is used as the printer-specific output color component data. , And by forming an image based on this, a color printer can be configured with a memory having a small number of bits.

〔The invention's effect〕

As described above, according to the present invention, it is possible to reduce the memory capacity required when inputting image information expressed in a page description language and outputting raster data to an image forming unit.

[Brief description of the drawings]

FIG. 1 is a block diagram of the color printer of this embodiment, FIG. 2 is a block diagram of the color printer of this embodiment, FIG. 3 is a block diagram of an address generator, and FIG. 4 explains the function of a pallet data conversion circuit. FIG. 5 is a block diagram of an image processing circuit, FIGS. 6 (a) and 6 (b) are image signals and other timing charts, FIGS. 7 (a) and 7 (b). ), FIG. 7 (c), FIG.
(D) and FIG. 7 (e) are explanatory diagrams of the PDL, and FIGS. 8 (a) and 8 (b) are flowcharts of the control. 2,5,6,7,8,3 ... Input means 4 ... Image storage means 5,6,7,31,3 ... Image expansion means, means for converting color numbers 35,33,34 ... Image Conversion means 10, 11, 16, 17 ... Image forming means

Continuation of the front page (56) References JP-A-59-163944 (JP, A) JP-A-59-163980 (JP, A) JP-A-60-243735 (JP, A)

Claims (1)

(57) [Claims] 1. An input means for inputting image information including image development control information and color data indicated in a page description language; the color data composed of a plurality of color components; and a data amount smaller than the color data. Storage means for storing a correspondence relationship with code data; converting the color data composed of the plurality of color components included in the image information into code data based on the correspondence relationship; and storing the code based on the image development control information. Rasterization processing means for performing rasterization processing on a memory using data and generating raster data indicating an output image; and reading out raster data indicated by the code data rasterized on the memory in synchronization with image formation by the image forming means. A color processing unit that performs color processing according to the output characteristics of the image forming unit and outputs the color processing to the image forming unit. Color image processing apparatus according to claim and.