JPH11190988A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make expansable a bit map image fast by erasing a drawing buffer in a short time. SOLUTION: An entire-area erasure time hold part 8 holds the time T1 when the entire area of the drawing buffer 7 is erased. A drawing erasure time hold part 9 holds the time T2 when the drawing buffer 7 is erased by using a drawing code. An erasure system selection part 10 compares the time T1 with the time T2 to select an erasure system which can erase the drawing buffer 7 in a shorter time. A drawing part 6 erases the drawing buffer 76 by the selected erasure system and gets ready to expand a next bit map image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus for performing processing for expanding data to be output to an image output device into a drawing buffer.

[0002]

2. Description of the Related Art In an image processing apparatus for supplying data to an image output device such as a CRT display device or a page printer,
Develop the generated image as a bitmap image in the drawing buffer. When a new image is to be drawn in the drawing buffer, the previously stored contents are erased for the entire writing target area of the drawing buffer. This is because the newly drawn image cannot be distinguished from the old image unless the storage contents of the entire area are erased. By the way, the bitmap image information has no structural information itself, unlike code information of a program or the like.
Therefore, in order to erase the contents stored in the drawing memory, a procedure of erasing old data by writing data for erasure in the storage area dot by dot is taken.

[0003] However, it takes a lot of time to erase the entire writing area of the drawing buffer. For example, 30
For a monochrome image with a resolution of 0 dpi (300 dots per inch), a memory capacity of 1 MB is required to store one A4 size image data, and 40
Approximately 59 for a 16 million color image with 0 dpi resolution
Requires MB memory capacity. Such a large-capacity drawing buffer is generally composed of a DRAM, and a process of writing zero data for each address is required for erasing its contents. The erasing process can be performed by one command like a flash memory. It cannot be finished.
For example, for a monochrome image of 300 dpi, several tens of milliseconds, 40
It took several seconds for a 16 million color image at 0 dpi. As described above, since it took a long time to erase the drawing buffer, it is not enough as an image processing device for an image output device such as a CRT or a page printer that requires high-speed generation of a bitmap image. Can not meet the demand.

Therefore, an apparatus for erasing the contents stored in the drawing buffer at high speed has been proposed (Japanese Patent Laid-Open No. 9-16).
138 publication). In this apparatus, coordinate values required for drawing an image, that is, a drawing code, are generated based on the code information, data “1” is written based on the drawing code at the time of writing, and data “0” is written based on the same drawing code at the time of erasing. Is written. This eliminates the need to first erase the entire area of the drawing buffer, so that the previously written data can be erased in a short time.

[0005]

The above-mentioned conventional apparatus has the following problems. The above-described conventional apparatus is configured to always use a drawing code when erasing a bitmap image in a drawing buffer. However, when the drawing code is complicated, it may take longer than writing data “0” in the entire writing area and erasing the previous stored content.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image processing apparatus which solves the above-mentioned problems and enables the storage contents of a drawing buffer to be erased at a high speed so that a bitmap image can be generated at a higher speed. And

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve the object, the present invention provides a drawing buffer for holding a bitmap image, and a drawing code generating means for generating a drawing code based on document data. A drawing means for drawing a bitmap image in the drawing buffer according to the drawing code, an erasing method for erasing the entire drawing buffer, and an erasing method for erasing the drawing buffer using the drawing code in a short time. Erasing method selecting means for selecting a method capable of erasing the drawing buffer, wherein the drawing means erases the drawing buffer by adopting the selected erasing method after drawing the bitmap image by the drawing code. The feature is that it is configured in

According to this feature, the time required for erasing only the bitmap image drawn in the drawing buffer using the drawing code is compared with the time required for erasing the entire drawing buffer. The one that can erase the drawing buffer is selected. Then, the drawing means expands the bitmap image according to the drawing code,
The drawing buffer is erased by adopting the method capable of erasing in a short time.

[0009]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a block diagram of an image forming system including the image processing device of the present invention. In FIG. 1, a document creation device 1 such as a personal computer
In this example, document data expressed in, for example, a page description language is created using a document creation application.
The created document data is transferred to the laser printer 2 via the network. The document data interpreting section 20 of the laser printer 2 interprets the document data using an interpreting means corresponding to the type of the page description language, and creates a drawing code.

The drawing code processing section 21 develops the image data into a bitmap on a drawing buffer (not shown) according to the drawing code. The bitmap-deployed image data is supplied to the image output device 22, and the image output device 22 outputs the print image 3 based on the supplied image data. Here, a laser printer is assumed as the image forming apparatus, but a display device that outputs an image to a CRT display device has the same configuration.

Next, the main functions of the laser printer 2 will be described. FIG. 1 is a block diagram showing the main functions of the laser printer 2. The document data interpreting unit 20 includes a drawing code generation unit 4 and a drawing code holding unit 5 that holds the generated drawing code. The drawing code generation unit 4 generates a drawing code, which will be described later in detail with reference to FIG. 3, based on the document data. The drawing code is a coordinate value necessary for developing the image in the drawing buffer.

The drawing unit 6 reads out the drawing code from the drawing code holding unit 5 in response to the write command, generates image data, and outputs it to the drawing buffer 7. The write command is input from the image output device 22. The drawing buffer 7 is configured as, for example, a band buffer that holds data of an area (band) obtained by dividing one page into a plurality of parts in order to be able to simultaneously process the development of the image data and the output of the developed data. Can be.

The whole area erasing time holding unit 8 includes a drawing buffer 7
The time T1 required to write the data "0" to the entire area is set in advance. When the drawing buffer 7 is configured by a band buffer, the time required to write data “0” to the entire area of the band buffer is time T1. The drawing erasing time holding unit 9 holds a time T2 required for erasing only the image data written in the drawing buffer 7 by the latest processing using the drawing code. The erasing method selection unit 10 determines the time T1 and the time T2.
And selects an erasing method that can erase the stored contents of the drawing buffer in a short time. That is, when the time T1 required for the entire area erasure is shorter, the erasing method of writing data “0” to the entire area of the drawing buffer 7 is selected. On the other hand, if the time T2 for erasing only the most recently written image data using the drawing data is shorter, the drawing color of the drawing code stored in the drawing code storage unit 5 is replaced with “0”. A method of erasing the storage contents of the drawing buffer 7 by drawing (redrawing) again is selected.

The times T1 and T2 required for erasing the area of the drawing buffer 7 may be measured or calculated. In the case of calculation, the time T1 can be obtained from the size of the drawing buffer 7. The time T2 can be calculated from the size of the drawing code and the analysis result of the content.

For example, the unit read access time of the drawing code holding unit 5 is Tread, the header analysis time of the drawing code is Thead, the analysis time per cell is Tcell, and the unit write access time to the drawing buffer 7 is Twrite. The number of accesses for reading is Nread, the number of cells is Ncell, and the number of accesses for writing drawing data is N
Assuming write, the time T2 required for drawing to erase the drawing code is obtained by the following equation. T2 = Nread × T
read + Thead + Ncell × Tcell + Nwrite × Twrite ...
(Equation 1).

It should be noted that a drawing code holding unit for erasing may be provided separately from the drawing code holding unit 5, and a drawing code used for erasing may be temporarily stored therein. Normally, in the color image processing apparatus, drawing is performed for each color, so that only the drawing code of the color used for drawing at this time may be used as the erasing drawing code. That is, only the drawing code of the color necessary for erasing is stored in the erasing code holding unit for erasing, so that unnecessary processing of the drawing code is not required, and the stored contents of the drawing buffer 7 can be erased more quickly. .

FIG. 3 is a diagram showing an example of the configuration of a drawing code. FIG. 1A is a schematic diagram showing the relationship between two cells. In the drawing code, the back cell 1 based on the front cell 11a is used.
1b is represented. However, the first cell is represented by a coordinate value based on the origin of the coordinates of the drawing buffer 7.

As shown in FIG. 3B, the drawing code 11 includes a header section 110 and a data section 120.
As shown in FIG. 3C, the header section 110 includes the number N of cells.
um, cyan (C), magenta (M) for color images,
Yellow (Y) and black (K) color values Colo
r, the total size of the drawing code. The data section 120 is a set of a plurality of cells.
As shown in (d), it is composed of a difference X in the X direction from the previous cell, a difference Y in the Y direction from the previous cell, and a run length RL of the cell. The cell difference and run length are shown in FIG.
The present invention is not limited to the method shown in FIG.

FIG. 4 is an example of the representation of a bitmap image using a drawing code. From the header section 110 shown in FIG. 4A, the number of cells is 10 and the drawing color is “25”.
It can be seen that the K color of 5 "and the total size of the drawing code are 38 bytes. The data section 12 of FIG.
According to 0, first, a line segment of run length “1” is drawn from the coordinate value (10, 4), and then the X coordinate is moved by “−2”.
The Y coordinate is moved by “1” and a line segment of run length “3” is drawn. Subsequently, the X coordinate is moved by “−4”, and the Y coordinate is moved by “1”.
Move to draw a line segment of run length “5”. Thereafter, by executing similar processing, a triangle as shown in FIG. 4C is drawn.

When erasing the contents stored in the drawing buffer 7 using the drawing data, the values in the drawing color field of the header section 110 are all replaced with "0" and the drawing is performed again. Then, all the black portions in FIG. 4C are replaced with white, and the erasure is performed.

FIG. 5 is a flowchart showing the drawing erasing process. In the figure, in the step S1, drawing is performed in the drawing buffer 7. At the same time, the writing time T2 is measured and stored in the writing erase time holding unit 9. In step S2, the image data is transferred from the drawing buffer 7 to the image output device 22. In step S3, the time T1 required to erase the entire area of the drawing buffer 7 is read from the entire area erase time holding unit 8. In step S4, the time T2 is read from the drawing erase time holding unit 9. In step S5, it is determined whether or not the time T1 is longer than the time T2.
If the time T1 is longer, the process proceeds to step S6 to execute the erasure using the drawing code. If the time T2 is longer, the process proceeds from step S5 to step S7, where the entire area of the drawing buffer is erased. When the processing of all the drawing codes is completed, step S8 becomes affirmative, and the processing ends.

Next, a second embodiment will be described. In the above-described embodiment, when erasing the storage contents of the drawing buffer 7, the user selects between erasing the entire area and erasing the drawing portion. On the other hand, in the second embodiment, an erase code corresponding to either one of the entire area erase and the erase of the drawing portion is generated and selected separately from the draw code in advance. Then, the drawing code holding unit 5 alternately arranges and holds the drawing code and the erasing code (erasing code group, erasing code group) for one drawing unit. With this configuration, the drawing unit 6 only needs to load the codes sequentially read from the drawing code holding unit 5 into the drawing buffer 7.

FIG. 6 is a block diagram showing the main functions of the laser printer 2 according to the second embodiment. Unless otherwise described, the same reference numerals as those in FIG. 1 denote the same or equivalent parts.
The drawing erasing time calculation unit 12 calculates the above formula (formula 1) from the size and content of the drawing code generated by the drawing code generation unit 4.
, The erase time T2 of the image data drawn by the drawing code is calculated, and stored in the drawing erase time holding unit 9.
The erasing method selecting unit 10 compares the entire area erasing time T1 with the drawing erasing time T2, and outputs a signal SEL1 when the entire area erasing time T1 is shorter, and outputs a signal SEL2 when the drawing erasing time T2 is shorter. Is output.

The whole area erasure code generation unit 13 generates a whole area erasure code, that is, a code for writing “0” in the whole area of the drawing buffer 7. The drawing erasure code generation unit 14 generates and holds a drawing erasure code in which the drawing color according to the drawing code is replaced with “0” based on the drawing code. The whole area code generation unit 13 generates and outputs a whole area erasure code in response to the SEL1. The drawing erasure code generator 14 generates and outputs a drawing erasure code in response to the SEL2. The drawing code holding unit 5 alternately reads and holds a drawing code and an erasure code. The drawing code and the erasing code are held as a set (code group) of codes included in a drawing unit processed at a time, for example, a band data unit obtained by dividing a page into a plurality.

FIG. 7 is a flowchart of a drawing erasing process according to the second embodiment. In FIG.
At 10, one unit of the drawing code group is read from the drawing code holding unit 5, and the image data is developed in the drawing buffer 7. In step S11, image data is output to the image output device 22. In step S12, one unit of erase code group is read from the drawing code holding unit 5, and the image data is developed in the drawing buffer 7. Step S13
Then, it is determined whether or not all the codes of the drawing mode holding unit 5 have been processed, and if the processing of all the codes is completed, the result of the determination in step S13 becomes affirmative, and the processing is terminated.

[0026]

As is apparent from the above description, according to the present invention, the time required to erase only the bitmap image drawn in the drawing buffer using the drawing code and the entire drawing buffer are erased. By comparing with the time required for the drawing, the one that can erase the drawing buffer in a short time is selected. Therefore, when the drawing code is simple, the next image data can be expanded in a shorter time than when the entire drawing buffer is erased, and even when the drawing code is complicated,
No erasing time is required beyond erasing the entire drawing buffer. As a result, the drawing buffer as a whole can be erased in a short time, and data can be efficiently supplied to an image output device that is required to generate a bitmap image at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of a laser printer according to an embodiment of the present invention.

FIG. 2 is a block diagram of an image forming system including a laser printer according to an embodiment of the present invention.

FIG. 3 is a diagram showing a structure of a drawing code.

FIG. 4 is a diagram showing a specific example of a drawing code.

FIG. 5 is a flowchart of image processing according to the first embodiment.

FIG. 6 is a block diagram illustrating a main configuration of a laser printer according to a second embodiment.

FIG. 7 is a flowchart of image processing according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Document creation apparatus, 2 ... Laser printer, 4 ... Drawing code generation part, 5 ... Drawing code holding part, 6 ... Drawing part, 8 ... Whole area erasing time holding part, 9 ... Drawing erasing time holding part, 10 ... Erasing method Selection section

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G09G 5/36 520 G06F 15/62 K 530 15/72 G

Claims (4)

[Claims] A drawing buffer for holding a bitmap image; a drawing code generating means for generating a drawing code based on document data; and a bitmap stored in the drawing buffer in accordance with the drawing code generated by the drawing code generating means. Drawing means for drawing an image; an erasing method for erasing the entire drawing buffer; and an erasing method for selecting a method capable of erasing the drawing buffer in a short time among erasing methods for erasing the drawing buffer using the drawing code. An image processing apparatus comprising: a selection unit; and wherein the drawing unit is configured to delete the drawing buffer by employing the selected deletion method after drawing the bitmap image by the drawing code. . 2. An erasing method for erasing a drawing buffer based on the drawing code, wherein the drawing means is configured to set the value of a drawing color based on the drawing code to zero when erasing the drawing buffer. The image processing apparatus according to claim 1, wherein: 3. A drawing buffer for holding a bitmap image, drawing code generation means for generating a drawing code based on document data, and a drawing erasure code for erasing the drawing buffer.
A drawing erasure code generating unit that generates based on the drawing code; an entire area erasing code generating unit that generates an entire area erasing code for erasing the entire area of the drawing buffer; An erasing method selecting unit that selects a user who can erase the drawing buffer, and selects a unit that generates the selected erasing code from the drawing erasing code generating unit and the entire area erasing code generating unit; A drawing code holding unit for alternately storing the erasure codes generated by the erasure code generation unit selected by the method selection unit; and a drawing code and an erasure code stored in the drawing code holding unit, which are read out in the order of storage. Drawing means for drawing a bitmap image in the drawing buffer. Image processing device. 4. The drawing erase code generated based on the drawing code is obtained by converting the drawing code so that a value of a drawing color according to the drawing code becomes zero. The image processing apparatus according to any one of the preceding claims.