JP2885890B2 - Recording control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a recording control device, more specifically, expands image data for each color component based on received recording data to a frame memory for each corresponding color component, and The present invention relates to a recording control device that outputs to a recording device.

[Prior Art] Conventionally, in a color printer, magenta (M), cyan (C),
The color was represented by four color dots of yellow (Y) and black (K). Therefore, the number of expression colors per pixel is eight.
Halftone dial processing such as dithering, average density, error diffusion, etc. has been performed to express natural images such as photographs, limited to colors.

[Problems to be Solved by the Invention] However, in this case, since gradation expression is performed by a plurality of pixels, resolution is degraded, a peculiar pattern is generated, and it is difficult to express a high-quality natural image. Atsuta.

On the other hand, in a display device such as a personal computer, 8 bits are assigned to each of the red (R), green (G), and blue (B) color components, and are represented by 1677.
For example, a color pallet that selects 256 colors from all colors and performs color expression is often used. In this case, since 256 colors can be expressed with one pixel, it is possible to express a very high-quality natural image. However, since the printer does not support a color palette, it has not been possible to print a high-quality natural image as described above.

The present invention has been made in view of the above problems, and not only allows a bitmap image of color image data and a palette code to be stored together, but also substantially reduces the number of bits constituting the palette code. It is an object of the present invention to provide a recording control device which eliminates the limitation, makes it possible to use a multicolor palette, and thereby makes it possible to record a color image from both color image data and a palette code.

[Means for Solving the Problems] A recording control device of the present invention for solving the problems has the following configuration. An area identification information storage unit for storing identification information for identifying an area represented by a pallet code; a storage unit for storing bit image data of color components and pallet code data in a predetermined frame memory; Conversion means for converting the pallet code stored in the image data into pixel data of a color that can be output to a color recording apparatus; and the data read from the frame memory, whether bit image data of a color component or a pallet code, the area identification information. Determining means for making a determination in accordance with the identification information stored in the storage means; and if the read data is determined to be a pallet code, the conversion means converts the color pixel data to the read pallet code. Output means for generating and outputting to the color image recording device; The frame memory has a number of plane memories corresponding to a recording color component, and when the number of bits of the pallet code is larger than the number of plane memories, the frame memory is stored in the frame memory over a plurality of adjacent pixels. It is characterized by doing.

Embodiment An embodiment according to the present invention will be described below in detail with reference to the accompanying drawings.

Generally, a laser beam printer receives a video signal and forms a visible image on a recording medium (recording paper), analyzes received data, develops it into a memory as a bit image, converts the image into a video signal, and converts the image into a video signal. It is composed of two parts, a printer controller for outputting to the engine. In the embodiment, an example applied to the printer controller will be described.

<Description of First Embodiment> FIG. 1 is a block diagram of a printer controller according to a first embodiment.

In the figure, 1 is an input terminal for receiving print data from an external host computer or the like, 2 is an interpreter for analyzing received print data, and 3 is an image data for each received color component in a frame buffer to be described later. This is a dot expansion circuit. 4 is a pallet data processing circuit, 5
Is a pallet area identification circuit. Reference numerals 6m, 6c, 6y, and 6k denote frame buffers, which correspond to magenta, cyan, yellow, and black color components, respectively, and one bit is assigned to each pixel. 7 is a read control circuit, 8 is a pallet decode circuit, 9 is a multivalued circuit, 10
Is a signal switching switch. Reference numeral 11 denotes an output terminal for outputting a video signal to the printer engine unit, and reference numeral 12 denotes an input terminal for inputting a color component ID signal or a line synchronization signal to be processed from the printer engine unit.

 The processing flow is briefly described as follows.

The description will be given on the assumption that information (palette area data) for specifying the area of the palette data is sent from the host computer.

The print data (control data,
The palette code, the image data for each color component, the character code, etc.) are first analyzed by the interpreter 2. Binary data for each color component, such as characters and line drawings, is output to the dot development circuit 3. The dot developing circuit 3 writes the binary data into a designated color component plane (frame buffers 6m, 6c, 6y, 6k) based on the input data.

On the other hand, if the received data is pallet code data (8 bits, ie, 256 colors are specified in the embodiment), the data is sent to the pallet data processing circuit 4.
For the pallet area data, the pallet area identification circuit 5
Sent to The palette table data is sent to the palette decode circuit 8 after converting the RGB data into MCYK data. Here, the pallet table data is data indicating which of the 16.77 million colors should be converted from the input 8-bit (256 colors) pallet code data. The pallet data processing circuit 4 converts the received pallet code (8 bits) into a frame buffer.
Write from 6m to 6k. At this time, as shown in FIG. 2, the upper 4 bits and lower 4 bits of the pallet code are divided and written into the frame buffers 6m to 6k. Therefore, the horizontal resolution is
1/2 of pixel density (resolution) developed by dot development circuit 3
become. That is, the resolution of the printer engine is now
400ppi (pixels / inch) both horizontally and vertically,
The vertical resolution does not change, but the horizontal resolution is 200 ppi.
Therefore, the resolution conversion is performed by the pallet data processing circuit 4 including the case where the resolution of the data sent from the host computer does not match the resolution of the printer engine, and the result is written into the frame buffers 6m to 6k. For example, if palette data is also sent at 400ppi,
The data is thinned out and written every other pixel. The pallet area identification circuit 5 holds the pallet area data received from the interpreter 2 in a register provided therein, and determines whether the pixel position indicated by the address (coordinate) generated by the read control circuit 7 is MCYK2 value data or a pallet code. It determines whether the data is data, and outputs a signal for controlling the switch 10.

FIG. 4 shows an example of a detailed block diagram of the pallet area identification circuit 5.

In the drawing, 20 to 23 are registers, 24 and 25 are comparison circuits, 2
6 is an AND circuit.

For example, it is assumed that a command for designating the inside of the rectangular area 14 shown in FIG. 3 as a pallet area is sent from the host computer. At this time, the interpreter 2 interprets the command and obtains the coordinates (x ₀ , y ₀ ) of the start point (upper left corner of the pallet area 14) and the coordinates of the end point (lower right corner of the pallet area 14) on the pallet area. (X ₁ , y ₁ ) is sent to the pallet area identification circuit 5. In palette area identifying circuit 5 receives the data, "x _0" in the register 20, "x _1" in the register 21, the register 22 "y _0", and stores the "y _1" in the register 23. On the other hand, the coordinates (x,
y) is also applied, and in the comparison circuit 24, To the AND gate circuit 26.

Similarly, in the comparison circuit 25, Is applied to the AND circuit 26.

As a result, "1" is output to the AND circuit 26 when the pixel currently being read is within the pallet area, and "0" is output outside the pallet area.

The read control circuit 7 controls the frame buffers 6m to 6k so that data is read from the frame buffers 6m to 6k in accordance with the synchronization signal of the engine section applied from the input terminal 12.

From the frame buffers 6m to 6k, data is read out in units of two pixels, that is, in units of 8 bits, for each of 6m, 6c, 6y, and 6k as shown in FIG. The signals are output to the pallet decode circuit 8 and the multi-value conversion circuit 9. The pallet decode circuit 8 receives a total of 10 bits of a pallet code of 8 bits and a plane ID signal (2 bits) indicating the MCYK color plane input from the input terminal 12 and outputs 8 bits of gradation information for each color plane. . In the case of the embodiment, the pallet decode circuit 8 is realized by a look-up table (RAM), and the table stored therein is table data transferred from the host computer side as described above. However,
If the data transferred from the host is RGB, the data is converted into MCYK data (including color correction of the engine) according to the printer engine in the interpreter 2 and stored. Accordingly, when a pallet code is input from the frame buffers 6m to 6k and a plane ID signal is applied from the terminal 12, the gradation information of the color indicated by the plane ID is output. The converted gradation information is applied to the terminal a of the switch 10. If the data subjected to the color masking process is stored in the table, the color masking process can be performed at the same time. In this case, however, the same data is output from the pallet decode circuit 8 twice in succession.
When outputting pixel data of a pixel, interpolation may be performed based on pixel data before and after the data. As the interpolation processing, for example, the average of each color component of the preceding and following pixels may be set as the color component of the target pixel.

On the other hand, the multi-level conversion circuit 9 extracts only the data (2 bits) of the plane indicated by the plane ID signal applied from the input terminal 12 from the data applied from the frame buffers 6m to 6k, and Of the 2-bit data,
Examine the data of dots to be scanned earlier, the data of "1" when been made in 8 bits are all "1" (i.e. hexadecimal FF _H)
And eight bits when been filed with "0" and outputs data of all "0" (= OO _H) to the terminal b of the switch 10. In the next clock, it examines the other bits, when similarly "1" is applied to OO _H to the terminal b of the switch 10 when the FF _H "0". In accordance with the control signal from the pallet area identification circuit 5, the switch 10 selects the signal on the terminal a when the current pixel data is within the pallet area, and selects the signal on the terminal b when the current pixel data is out of the pallet area. A gradation signal is output to the printer engine. The printer engine receives this gradation signal and performs, for example, pulse width modulation processing (PWM processing).
To generate visible pixels on a recording medium by a known electrophotographic technique.

<Description of Second Embodiment> FIG. 5 is a block diagram of a printer controller according to a second embodiment.

In the figure, 30 is a pre-filter, 31 is a sub-sampling circuit, 33 is a pallet decode circuit, and 34 is an interpolation circuit.
In other configurations, the same reference numerals are given to components having the same functions as those in FIG.

Hereinafter, only portions different from the embodiment of FIG. 1 will be described.

The pallet code data applied from the interprinter 2 is subjected to a pre-filter 30 to remove a component (ie, a high-frequency component in an oblique direction) that becomes aliasing noise at the time of sub-sampling. The data is subsampled) and written into the frame buffers 6m to 6k by the palette data processing circuit 4.

FIG. 6 is a block diagram showing the structure of the pre-filter 30. In the figure, 35 is a pallet decode circuit, 36 is a spatial filter, and 37 is a pallet encode circuit.

Since the signal input to the pre-filter 30 is not a baseband signal but a coded signal, it is not possible to apply a spatial filter as it is (for example, the color of the code “1” and the color of the code “3”). Is not necessarily the color of the code "2"). Therefore, the baseband signal (RGB or MCYK) is temporarily output by the palette decode circuit 35.
After the return, the spatial filter 36 eliminates oblique high-frequency components, which are aliasing noises, and outputs the result to the pallet encoding circuit 37. The pallet encoding circuit 37 converts the pallet code again into a pallet code, and then applies a signal to the sub-sampling circuit 31. If aliasing noise due to sub-sampling does not pose a problem, the pre-filter 30 becomes unnecessary.

FIG. 7 is a diagram showing a sampling pattern on a page. In the figure, black circles indicate pixels stored in the frame buffers 6m to 6k, and white circles indicate pixels to be thinned out. As shown in the figure, the sub-sampling circuit 31 shifts the pixels to be thinned out one line at a time by one pixel. At this time, the pallet code is stored for each block (a set of white circles and black circles in the figure) surrounded by a square in the figure.

On the other hand, signals read from the frame buffers 6m to 6k are input to the input terminal 12 of the MCYK by the pallet decode circuit 33.
After being converted into a gradation signal of a color indicated by the applied plane ID signal, a signal of “OO _H ” is inserted into a portion corresponding to the pixel decimated by the sub-sampling 31, and the interpolation circuit 34
Is applied to The interpolation circuit 34 interpolates the pixels thinned out by the filter corresponding to the spatial filter 36 shown in FIG. 6 from the surrounding pixels which have not been thinned out. Therefore, a signal is applied to the terminal a of the switch 10 at the same rate as that without subsampling.

In the second embodiment, since the sub-sampling is used, the resolution in the oblique direction slightly deteriorates, but the spatial resolution in the horizontal and vertical directions hardly changes.

<Description of Third Embodiment> FIG. 8 is a block diagram of the third embodiment.

In the figure, 40 is a resolution conversion circuit, 41 is a pallet encoding circuit, 42 is a pallet code writing circuit, and 43 is a pallet decoding circuit. Also in this case, the blocks having the same functions as in the first embodiment are given the same numbers.

Hereinafter, only the portions different from the first embodiment will be described.

In the third embodiment, the signal transmitted from the host is not a palette code but a baseband signal (RGB or M-bit).
(CYK signal).

The baseband signal applied from the interprinter 2 is converted to a resolution (pixel density) on the printer engine side by a resolution conversion circuit 40 and applied to a pallet encoding circuit 41. For example, when the resolution of the print engine is 400 ppi, the resolution conversion circuit 40 converts the signal into a signal of 200 ppi in the main scanning method and 400 ppi in the sub-scanning direction.

The resolution-converted signal is converted to a pallet code by a pallet encoding circuit 41. The pallet encoding circuit 41 is a known circuit that receives the gradation of each color plane as an input and outputs a pallet code.

The converted pallet code signal is written by a pallet code writing circuit 42 to a corresponding portion of the frame buffers 6m to 6k.

On the other hand, the signals read out from the frame buffers 6m to 6k are converted by the pallet decode circuit 43 into gray scale signals of the color indicated by the plane ID signal applied from the input terminal 12 of MYCK, and the terminal a of the switch 10 Is applied to The look-up table of the palette decoding circuit 43 stores data corresponding to the palette encoding circuit 41. However, since the output of the palette decoding circuit 43 is MCYK data, the palette encoding circuit 41 and the palette decoding circuit
According to 43, the RGB signal is converted into a YMCK signal.

<Description of Fourth Embodiment> FIG. 9 is a block diagram showing a fourth embodiment.

In the figure, 44 is a resolution conversion circuit, 45 is a spatial filter, 46 is a sub-sampling circuit, and 47 is a pallet decoding circuit. The blocks having the same functions as those of the third embodiment (FIG. 8) are denoted by the same reference numerals. Hereinafter, only portions different from the third embodiment will be described.

In the fourth embodiment, the deterioration of the resolution in the horizontal direction (main scanning direction) is suppressed by using subsampling in the third embodiment.

The baseband signal applied from the interprinter 2 is converted to the resolution (pixel density) of the printer engine by the resolution conversion circuit 44 and applied to the spatial filter 45. For example, if the resolution of the printer engine is 400ppi,
The resolution conversion circuit 40 is 400 ppi in the main scanning direction and sub-scanning direction.
The input baseband signal is converted so that the signal becomes

The resolution-converted baseband signal is converted to a spatial filter.
At 45, high-frequency components in the oblique direction, which are aliasing noises at the time of subsampling, are removed, thinned out at a subsampling circuit 46 into a form as shown in FIG. 7, and converted to a pallet code at a pallet encoding circuit 41. Are written into the frame buffers 6m to 6k by the pallet code writing circuit 45. In this embodiment, since the signal applied from the interpreter 2 is a baseband signal, the pallet decoding circuit 35 as shown in FIG. 6 is not required. Also, because of the baseband signal, resolution (pixel density) conversion is easy.

On the other hand, the signals read from the frame buffers 6m to 6k are input to the input terminal 12 of the MCYK by the palette decode circuit 47.
The signal is converted to a gradation signal of the color indicated by the applied plane ID signal, and a signal of “OO _H ” is inserted into a portion corresponding to the pixel decimated by the sub-sampling 46 and applied to the interpolation circuit 34. You. The interpolation circuit 34 is a filter corresponding to the spatial filter 45, and interpolates the thinned-out pixels from the surrounding pixels which have not been thinned out. Therefore, a signal is applied to the terminal a of the switch 10 at the same rate as in the case without subsampling.

In the fourth embodiment as well, the sub-sampling is used as in the embodiment of FIG. 5, so that the resolution in the oblique direction slightly deteriorates, but the spatial resolution in the horizontal and vertical directions hardly changes.

As described above, according to this embodiment, the 8-bit pallet code is divided into upper 4 bits and lower 4 bits, and the above data is stored in two adjacent pixels of the frame buffer. It is possible to construct a controller section of a printer that supports both binary data and 8-bit pallet code data.

In the embodiment, a laser beam printer has been described as an example of the printer engine unit. However, the present invention is not limited to this.

In the embodiment, the pallet code is described as 8 bits. However, when the pallet code is 4 bits (16 colors are selected), each bit may be divided and stored in each frame memory.
In the case of a bit (4096 color selection), it is sufficient to store the data over three pixels, so that the present invention is not limited by this.

[Effects of the Invention] As described above, according to the present invention, it is possible to not only allow the bitmap image of the color image data and the palette code to be stored together, but also to reduce the number of bits constituting the palette code. Thus, it is possible to use a multi-color palette, thereby recording a color image from both color image data and a palette code.

[Brief description of the drawings]

FIG. 1 is a block diagram of a printer controller according to the first embodiment, FIG. 2 is a diagram for explaining a method of storing a pallet code in a frame buffer, FIG. 3 is a diagram showing a pallet area on a page, FIG. FIG. 5 is a block diagram of a pallet area identification circuit in the first embodiment, FIG. 5 is a block diagram of a printer controller in the second embodiment, FIG. 6 is a block diagram of a pre-filter in the second embodiment. FIG. 7 is a diagram showing a state of sub-sampling in the second embodiment, FIG. 8 is a block diagram of a pallet region identification circuit in the third embodiment, and FIG. 9 is a pallet region identification in the fourth embodiment. FIG. 3 is a block diagram of a circuit. In the figure, 2 ... interpreter, 3 ... dot development circuit, 4 ... pallet data processing circuit, 5 ... pallet area identification circuit, 6
m, 6c, 6y and 6k: frame buffer, 7: memory read control circuit, 8, 33, 35, 43 and 47: pallet decode circuit,
9 Multi-value conversion circuit, 10 Signal switch, 30 Pre-filter, 31 and 46 Interpolation circuit, 34 Interpolation circuit, 36 and 45
Spatial filters, 37 and 41 ... pallet encoding circuit, 40
And 44 a resolution conversion circuit and 42 a pallet code writing circuit.

Claims (2)

(57) [Claims] 1. Area identification information storage means for storing identification information for identifying an area represented by a pallet code; storage means for storing bit image data of color components and pallet code data in a predetermined frame memory; Converting means for converting the pallet code stored in the storage means into pixel data of a color that can be output to a color recording device; and determining whether the data read from the frame memory is bit image data of a color component or a pallet code. Judging means for judging according to the identification information stored in the area identification information storage means; and when the data read by the judging means is judged to be a pallet code, the conversion means applies a color to the read pallet code. Output means for generating pixel data and outputting the pixel data to the color image recording apparatus. The frame memory has a number of plane memories corresponding to a recording color component, and when the number of bits of the pallet code is larger than the number of plane memories, the frame memory is stored in the frame memory over a plurality of adjacent pixels. A recording control device. 2. When the number of bits constituting the pallet code is larger than the number of plane memories constituting the frame memory and is not more than twice the number of plane memories, the storage means reduces the number of pixels to 1/2 by sub-sampling. 2. The recording control device according to claim 1, wherein a pallet code is stored in the frame memory after thinning.