JPH03158257A - Multi-color recording device - Google Patents

Abstract

PURPOSE:To obtain images with higher quality by a method wherein for continuous-cone image signals in a range of low gradation degrees, recording is performed through conversion which does not require page memory, etc., for all colors, and for continuous-tone image signals in a range of high gradation degrees, recording operation is performed by converting them into binary encoded image signals. CONSTITUTION:A control device 25 applies conversion on RGB signals which are input, referring to a table 26, and outputs to a color conversion circuit 27, and at the same time, controls change-over operation of multiplexers 28, 33. The color conversion circuit 27 converts the RGB signals to YMC signals and writes them in image memories 29Y-29C and character memories 30Y-30C in order. Data which are read from the image memories 29Y-29C are changed over by the multiplexer 33 and output to a printer engine in order. Also, for data which are read from the character memories 30Y-30C, their black component is extracted by a character flag discrimination device 31, and the data are written in a character memory 30BK and are output to the printer engine through the multiplexer 33. By this method, the recording image quality can be improved without increasing the memory capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a multicolor recording device that forms multicolor images, such as a laser beam printer or an LED printer.

[Prior Art] This type of multicolor recording device is widely used as an output device for computers and the like.

For example, as shown in FIG. 9, the basic configuration of a laser beam printer includes a printer engine 51 that prints on a photosensitive drum based on dot data, a printer engine 51 that receives code data sent from an external host computer 54, The printer controller 52 generates page information consisting of dot data based on the data, and sequentially sends the dot data to the printer engine 51.

In addition, the host computer 54 uses a floppy disk 55 containing various application software.
Load one application software and start the program.

For example, if the application software performs color image processing, the user can create and store a large amount of multicolor information.

On the other hand, FIG. 10 is a block diagram showing the signal processing circuit of the printer controller 52, and FIG. 11 is a timing chart showing the transfer sequence.

The R (red) signal, G (green) signal and B (blue) signal which are color image signals from the host computer 54 are converted by the color conversion means 3 into an M (magenta) signal which is a color image signal for printing,
The signal is converted into a C (cyan) signal, a Y (yellow) signal, and a BK (black) signal, and each is stored in the page memory 1 as a dot map. Then, the data in the page memory l is changed to Y, M, C,
The signals are read out in the order of BK and output from the OR gate 12 to a laser driver (not shown).

Further, an image signal representing a character such as a letter made of a combination of toner primary colors is input as a B1 signal. This Bi-fold signal is combined with the image signal from the switching means by the OR gate 12 and output to the laser driver.

The image transfer order is as shown in FIG.

The output signal is transmitted four times in response to the RGB signals from the host computer 54.

[Problems to be Solved by the Invention] However, in the above conventional example, it is not possible to clearly record characters such as letters by ORing with the image signal from the Bi-multiple signal switching control means 2. A large amount of image memory is required to convert the multicolor recording signal into a color image signal for printing and to develop and store the dot map in the page memory 1.

For example, the RGB signals of one page of A4 size are Y, M,
When performing color separation using C and BK toners, each color has 8 gradations.
In the case of bit, 32 in the case of monochrome binary image.
Requires twice as much memory.

For this reason, the memory capacity of the printer controller 52 becomes large, which poses a disadvantage in terms of device size, cost, and economy.

Moreover, since the Bi-fold signal must be input separately from the RGB signal, 2. For example, when forming an image based on an image signal read by an image reader, it is not possible to clearly record characters such as letters. , there is also the problem that the image quality deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multicolor recording apparatus that can improve the quality of recorded images without increasing memory capacity.

[Means for Solving the Problems] In order to achieve the above object, a multicolor recording device according to the present invention forms a multicolor image based on multivalued image signals of a plurality of colors. selection means for switching and selecting one color multi-value image signal from among the multi-value image signals;
determining means for determining whether or not the gradation level of the multi-valued image signal selected by the selection means is within a predetermined range; It is characterized in that mutually different transformations are applied to the multivalued image signals of the furniture.

Further, in the multicolor recording device, a recording operation for each color is sequentially performed based on a multivalued image signal having a gradation level that is not within the range;
The present invention is characterized in that, in addition to this recording operation, a recording operation is performed based on a multivalued image signal having a gradation within the above range.

[Operation] According to the present invention, a multi-value image signal having a gradation level within a predetermined range and a multi-value image signal outside the range are subjected to mutually different conversions.

For example, in a multi-valued image signal of an image including letters, characters, etc., the level: JAIf of the portion of the letters, characters, etc. is in a high range (close to the binary image signal). In such a case, multi-value image signals in a low gradation range are recorded by performing conversion that does not require page memory, etc. for all colors, and multi-value image signals in a high gradation range are recorded. can be converted into, for example, a binary image signal and stored in a page memory or the like, and a recording operation can be performed. Therefore, without requiring huge storage capacity,
Furthermore, it is possible to record high-quality images with clear text and characters.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a color conversion processing section in a printer controller of a multicolor recording apparatus according to an embodiment of the present invention. Note that the overall configuration of this multicolor recording apparatus is shown in FIG. 9 mentioned above, and will be explained using the same reference numerals. In the figure, reference numeral 25 denotes a control means that converts the input RGB signals as described later with reference to a table 26, and outputs them to a color conversion circuit 27.
Controls the switching operation of multiplexers 28 and 13, which will be described later. The color conversion circuit 27 converts RGB signals into YMC signals, and sequentially writes them into image memories 29Y to 29C and character memories 30Y to 30G.
The data read from 29G is switched by a multiplexer 33 and sequentially output to the printer engine.

Further, the black component of the data read from the character memories 30Y to 30C is extracted by the character flag determining means 31 and written into the character memory 308K. Further, black (BK) character data is outputted to the printer engine via the character memories 308K to 308m and the multiplexer 33.

FIG. 2 is a diagram showing the contents of the table 26. In this embodiment, the RGB signal is a multivalued image signal with 8-bit gradation. The gradation level of this input image signal is OOH~FDH
(rH, J indicate hexadecimal display), the output data represents the upper 4 bits or the 2 lower 4 bits.
This is 8-bit data with bits being OH. Furthermore, if the gradation level of the input image signal is FEH or FFH, the pixel is judged to constitute a character or the like, and the upper 4 bits of the output data are OOH, and the lower 4 bits are OOH.
The bits (rXJ portion in the figure) are set as described later. FIG. 3 is a diagram for explaining output data of the control means 25. As mentioned above, the upper 4 bits of the output data (
b4-b7) are image data representing gradations, and b4-b7 are subjected to RGB→YMC conversion in the color conversion circuit 27 based on toner characteristics, etc., and are provided to image memories 29Y-29C. At this time, in the image memories 29Y to 29C, the data that has already been stored is ORed and stored. Also, the lower 4 of the output data
The pitches (bo to b3) are flags of each color.

For example, when an R signal of gradation level FEH or FFH is input, the Y flag and the M flag are ON, that is, b3. b
2 or “l”, b3°b2. The output of bl is written into the character memories OY, 30M, and 30C by ORing the data already stored for each bit. In addition, at this time, the gradation level of any two of R, G, and B is FEH.
Or in the case of FFH, character memory 30Y, 30 Kaku, 30
All C becomes rlJ, but for example, when the gradation level of R and G signals is FEH or FFH, the color conversion circuit 27 converts bO-b3 so that only character memory 30Y becomes rlJ. Good too. In this way, it is possible to clearly reproduce the eight-color characters included in the image.

The operation in the color conversion process will be described below with reference to the flowchart in FIG. 4 and the time chart in FIG.

First, in step Sl, an R signal is input as the image signal. Then, it is determined whether the gradation level of each image data is within a predetermined range (FE) I to FFH) (step S2). If affirmative, the upper 4 bits are set to OH, and the lower 4 bits are set to the corresponding flag (b2, b3) is turned on (step S3). This flag is written into character memories 30Y and 30-, respectively. If the above judgment is negative, the lower 4 bits are set to OH and the upper 4 bits are output as image data (step S4). This image data is color-converted and written into the image memories 29Y and 29M. However, the predetermined range here may be a certain value, a certain value or more, or a certain range.

The above operation continues until the R data is completed (period T in Figure 5).
l l) When the process is repeated for all R data, the process advances from step S5 to step S6, and image data is output from the image memory 30Y (step S7), whereby a yellow recording operation is performed, and then Returning from step S8 to step S6, image data is output from the image memory 30, and a magenta recording operation is performed (period T12 in FIG. 5).

Next, in steps 89 to S16, operations similar to steps 81 to S8 are performed for the G data. That is, based on the G data input in period T13 in FIG. 5, yellow and cyan recording operations are performed in period T14.

However, when writing to the image memory 30Y, :IOc, OR is performed with data already stored. That is, when 4H has already been stored and 3H data is output from the two-color conversion means 27, 4H is stored. Further, when writing to the character memory: 1OY, 30(:), the above-described process may be performed, or the data may be written by ORing with the data already stored.

Further, in steps 317 to S24, operations similar to steps 89 to S16 are performed for the B data.

That is, magenta and cyan recording operations are performed in period T16 based on the B data input in period T15 in FIG.

With the above operations, full-color recording for pixels determined to be image data in period T1 is completed.

Next, for pixels determined to be letters or characters, black color is first extracted (step 325.S
26). Next, in steps S27 and 328, black data is output to record black, in steps 329 to S31, yellow is recorded, in steps 332 to S34, magenta is recorded, and in steps S5 to S38, cyan is recorded. Make a record. As a result, characters, characters, etc. are recorded during period Tl in FIG. Each of the above-mentioned recording operations is performed on the same recording paper, and since characters, characters, etc. are converted into binary data, it is important to record clearly. Furthermore, the memory capacity can be reduced to 16/:12 compared to the case where page memories are provided for four colors.

FIG. 6 shows a second embodiment of the invention. In FIG. 6, parts corresponding to those in FIG. 1 are given the same reference numerals. In this embodiment, an image memory 298K is provided, and even when it is determined that the data is image data, black extraction is performed, and the image data and character data are simultaneously recorded.

The operation will be described below with reference to the flowchart in FIG. 8 and the time chart in FIG. First, steps E1-E
5, steps Sl-S5 in FIG. 4 in the above-mentioned embodiment.
The R data is input in the same manner as in the image memory 29.
Y, 29M and character memory 30Y, :10! Data is written to II. However, in this example, RGB→YMC
This embodiment differs from the previous embodiment in that data is converted using a table 26 after conversion. Next, the process proceeds to step E6 without outputting data from the image memory or character memory.

In steps E6 to EIO, processes similar to steps 89 to S13 in FIG. 4 in the above-described embodiment (input of G data, etc.) are performed, and in steps Ell to E15, processes similar to steps S17 to S21 in FIG. B data input, etc.) is performed.

Next, in step E16, black color is extracted. That is, black extraction is performed by referring to the image memories 29Y to 29G, and is written to the image memory 298K.
The value of 9C is correspondingly reduced.

Further, character memories 30Y to IOC are referred to to perform black extraction and written into character memory 308K, and unnecessary Y to C flags are deleted from character memories 30Y to 30C.

Next, in step E17, the image memory 29Y is referred to, and if the data is OH in step E18, the data in the character memory 30Y is output (step E19).
, when the data is not 0)1, the image memory 29
The data of Y is output (step E20). Actually, such processing is performed by OR gate 34Y. When the processing for all pixels is completed, the yellow recording operation ends, and the process advances from step E21 to step 22.

In step E22 NE26, the same operation as in steps E17 to E21 is performed for magenta, and in steps E27 to E31, steps EI7 to E are performed for cyan.
21 is performed, and further steps E32 to E are performed.
36, a similar operation is performed for black color, and all processing steps are completed.

In this example, since black extraction is performed even when it is determined to be image data, it is possible to reproduce a high-quality image data image, and also to binarize the data for characters and characters. Because of this, clear reproduction is possible.

In the above embodiments, the recording method is assumed to be an electrophotographic method, but other recording methods may be used.

[Effects of the Invention] As explained above, according to the present invention, the recorded image quality can be improved without increasing the memory capacity.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a multicolor conversion processing section in a printer controller of a multicolor recording apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the contents of the table 26 having the configuration shown in the first diagram. FIG. 3 is a diagram for explaining the output data of the control means 25 in FIG. 1, FIG. 4 is a flowchart showing the operation of the configuration shown in FIG. 1, and FIG. 5 is a diagram showing the input/output operation of the configuration shown in FIG. FIG. 6 is a block diagram showing the configuration of another embodiment of the present invention. FIG. 7 is a flowchart showing the operation of the configuration shown in FIG. 6, FIG. 8 is a time chart showing the input/output operation of the configuration shown in FIG. 6, and FIG. 9 is a recording device! (laser printer), FIG. 1O is a diagram showing the configuration of the prior art, and FIG. 11 is a time chart of input/output operations of the configuration shown in FIG. 1O. 25... Control means 26... Table 27... Color conversion means 3 28, -34-... Multiplexer

Claims (2)

[Claims] (1) In a multicolor recording device that forms a multicolor image based on multivalue image signals of a plurality of colors, a selection means for switching and selecting a multivalue image signal of one color from among the multivalue image signals of a plurality of colors; , determining means for determining whether or not the gradation level of the multi-valued image signal selected by the selection means is within a predetermined range; A multicolor recording device characterized by performing mutually different conversions on multivalued image signals of gradations. (2) In the multi-color recording apparatus according to claim 1, a recording operation is performed based on a multi-value image signal having a gradation level outside the range, and, apart from this recording operation, a multi-value image signal having a gradation level within the range is performed. A multicolor recording device characterized in that a recording operation is performed based on an image signal.