JP2537851B2 - Image scaling processor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image scaling processing apparatus for performing image scaling processing (enlargement or reduction processing).

2. Description of the Related Art A conventional image scaling apparatus stores input image information in a memory. When a scaling request is made, the input image information (raw data of the input image) is read from the memory and scaled by a bit operation. It was designed to generate double image information.

The contents of this processing will be described with reference to FIGS. 8 and 9.

FIG. 8 shows an example of input image information. The horizontal row is a pixel row of one line, and black pixels are hatched.

To obtain the scaled image information that is obtained by reducing the input image by 1/2 in the main operation direction and the sub-scanning direction, take the logical sum of two consecutive pixels on the line, or thin out every other pixel. By reducing the number of pixels by half, the size is reduced in the main scanning direction. The reduction in the sub-scanning direction reduces the number of lines to half by thinning out every other line or taking the logical sum of two consecutive lines.

Through such reduction processing, reduced image information as shown in FIG. 9 is obtained.

The enlargement is performed by increasing one pixel to two pixels or a plurality of pixels in the main scanning direction and increasing one line to two lines or a plurality of lines in the sub scanning direction.

However, according to such a configuration, since the scaled image information is directly generated from the input image information, the input image information is input until the scaling process is completed and the input image information becomes unnecessary. Since the image information must be resident in the memory, there is a problem in that the memory usage efficiency is low.

Further, since the scaled image information is generated by direct bit manipulation of the input image information, the number of accesses to the input image information is large, and the time from generation of the scaling processing request to generation of the scaled image information is large. There was also the problem of being long.

The present invention has been made in view of the above-mentioned problems, and can improve the memory usage efficiency related to the storage of input image information, and can also display the scaled image information in a short time after the scaling processing request is generated. An object is to provide an image scaling processing device that can be generated.

Means for Solving the Problems In order to solve the above problems, the present invention generates and stores a change point table representing the number of pixels from the head of a black and white change point for each main scanning line of input image information. A change point table generating means for storing the change point table, a calculating means for directly multiplying the value of the change point table by a scaling factor, and a variable scale image information generating method based on the value of the change point table after multiplication by the calculating means. It has a structure.

The configuration of such a scaling processing apparatus of the present invention will be further described with reference to the claim correspondence diagram of FIG.

As shown in the figure, the scaling processing apparatus of the present invention comprises a table generation means, a storage means, a calculation means and an image generation means.

The table generation means detects the black and white change points for each line of the input image information, generates a change point table indicating the number of pixels from the line head of each change point, and stores it in the storage means. The calculation means multiplies the value of the change point table by the scaling factor and outputs the multiplication result. This multiplication result represents the number of pixels from the beginning of the line of the change point on the line of the scaled image. The image generation unit generates the scaled image information based on the output information of the calculation unit.

Action The present invention, by the above-mentioned configuration, eliminates the need to make the input image information resident in the memory until the scaling process is completed. Since the change point table is the compressed count information of the input image information, the storage space can be small.
Therefore, it is possible to significantly improve the memory use efficiency, as compared with the conventional device that requires the input image information to be resident in the memory.

Further, the process of multiplying the value of the change point table, which is the count information, by the scaling factor, and generating the scaled image information based on the multiplication result is performed by directly accessing the input image information many times and directly operating the scaled image by bit operation. It can be performed much faster than the process of generating information. Moreover, the change point table can be generated before the scaling request is issued. Therefore, the time from the generation of the scaling request to the acquisition of the scaled image information can be significantly shortened.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing a hardware configuration of an image scaling processing apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 is a microprocessor, and 2 is a ROM storing a scaling processing program including a multiplication routine and the like. The calculation means and the image generation means shown in FIG. 1 are realized by the processing program and the function of the microprocessor 1. The table generating means is realized by dedicated hardware described later with the support of the processing program and the function of the microprocessor 1.

Reference numeral 3 denotes a RAM, which can be accessed from the microprocessor 3 via the system bus 4. The storage space of the RAM 3 includes an image buffer area 5 for temporarily storing input image information or scaled image information, and a change point table storage for storing a change point table generated by the table generating means. Area 6 (corresponding to the storage means), a scaling change point table storage area 7 for storing the change point table after being multiplied by the calculation means, and other temporary storage of data being processed. It is used as a work area for

As dedicated hardware for realizing the table generating means, a line input buffer 8, a buffer address counter 9, a line end detection circuit 10, and a change point detection circuit
11, there are a change point table buffer 12 and a table address counter 13.

The line input buffer 8 is a high-speed buffer that temporarily stores input image information for one line, and the buffer address counter 9 generates an address of the line input buffer 8. The value of the buffer address counter 9 is also used as the number of pixels from the beginning of the line at the change point. In the read period of the line input buffer 8 (change point table generation processing period), the change point detection circuit
The increment signal S1 and the read timing signal S2 are supplied from 11 to the buffer address counter 9 and the line input buffer 8, respectively.

The change point detection circuit 11 examines black and white inversion of the image information output from the line input buffer 8 and detects the inversion pixel as a change point. When the change point is detected, the increment signal S3 and the write timing signal S4 are sent to the table address counter 13 and the change point table buffer 12. In addition, the change point detection circuit 11 causes the buffer address counter 9 to increment each time
The increment signal S5 is sent to the internal counter of the line end detection circuit 10.

The internal counter of the line end detection circuit 10 is preset with a value corresponding to the number of pixels for one line from the system bus 4 before the start of the change point table generation process for one line, and the line input buffer 8 outputs the final value of one line. When the image is output, a carry signal is output. The line end detection circuit 10 determines the line end by the generation of this carry signal, notifies the microprocessor 1 by the interrupt signal S6, and sends the end signal S7 to the change point detection circuit 11.

The change point table buffer 12 is for temporarily storing a change point table for one line. The table address counter 13 is a counter for generating the address of the change point table buffer 12.

Regarding the image scaling processing configured as described above, the scaling processing operation will be described below.

First, the operation of generating the change point table will be described.
It is assumed that input image information has been input to the image buffer area 5 from an image input device (not shown), a change point table for a certain line has already been created, and has already been stored in the change point table storage area 6.

The system bus 4 is controlled by the microprocessor 1.
Through the image buffer area 5, the image information of the next line is transferred to the line input buffer 8. After this transfer, the microprocessor 9 causes the line end detection circuit 10
The internal counter is preset and the buffer address counter 9 is reset, and the change point detection circuit 11 is activated. The table address counter 13 is also reset by the microprocessor 1 when the processing of the previous line is completed.

Under the control of the change point detection circuit 11, the image information is sequentially output from the head pixel of the line in pixel units from the line input buffer 8. The change point detection circuit 11 determines the input pixel as a change point when a black pixel is input subsequently to a white pixel or a white pixel is input subsequently to a black pixel, and generates a write timing signal S4. Then, the value of the buffer address counter 9 (the number of pixels from the beginning of the line of the change point) is written in the change point table buffer 12, and immediately after that, the increment signal S3 is transmitted to increment the table address counter 13. After that, the increment of the buffer address counter 9 and the read operation of the line input buffer 8 are restarted.

During such an operation, the internal counter of the line end detection circuit 10 is sequentially incremented by the increment signal S5. When the last pixel of the line is output from the line input buffer 8, the line end detection circuit 10 outputs an interrupt signal S6 and an end signal S7.

In response to the end signal S7, the change point detection circuit 11 outputs the write timing signal S4, and the value of the buffer address counter 9 at that time (incremented by 1 after the output of the last pixel) is the change point table buffer 12
The change point detection circuit 11 stops its operation. That is, it is considered that there is a virtual change pixel next to the last pixel of the line. Further, it is considered that there is a virtual white pixel in front of the head pixel of the line, and when the head pixel is a white pixel, this is not detected as a change pixel.

When the interrupt signal S6 is generated, the microprocessor 1 reads the value of the table address counter 13 (representing the size of the change point table generated in the change point table buffer 12) and stores it in the work area on the RAM3. The table address counter 13 is reset. Next, the microprocessor 1 transfers the change point table generated from the change point table 12 to the change point table storage area 6. This completes the operation of generating the change point table for one line.

By the same operation, the change point table of each line of the input image information is sequentially generated and stored in the change point table storage area 6. The input image information in the image buffer area 5 need not be saved after the change point table is generated. Since the change point table is count information obtained by compressing or encoding the input image information, it can be stored in a storage space much smaller than the storage space of the input image information.

FIG. 3 shows an example of input image information. FIG. 4 shows the contents of the change point table generated for the lines of the input image information and.

Next, the operation of generating the scaled image information based on the change point table will be described. It should be noted that this operation is executed by the microprocessor 1 according to the corresponding program when the scaling request is given to the microprocessor 1 in the form of an interrupt or the like.

First, an operation of generating information of an image obtained by enlarging an input image twice in the main scanning direction and the sub-scanning direction will be described. FIG. 6 is a schematic flowchart of this operation.

In step 1, the value is multiplied by the scaling factor (in this case, the scaling factor is 2) in order from the transition point table of the first line stored in the transition point table storage area 6. The change point table after this multiplication is stored in the variable change point table storage area 7 as a variable change point table.

When the one-line scaling change point table is stored, it is determined in step 2 whether or not an unprocessed change point table remains in the change point table storage area 6. If there is an unprocessed change point table, the process of step 1 is executed for the change point table of the next line.

When the scaling operation is executed for all the change point tables, the process proceeds to the step 3 and the subsequent steps of the scaling image generation processing.

First, in step 3, the image buffer area 14 is cleared (the input image information is unnecessary at this point).

In step 4, image information of one line is generated from the value of the leading scaling change point table stored in the scaling change point table storage area 7, and the image buffer area 14
Is stored in the first line position of. This process is performed by making white pixels continuous until the first change point, making black pixels continuous from that change point to the next change point, and similarly generating pixels by inverting black and white at each change point. Be seen. Since the number of pixels from the beginning of the line to each change point is doubled in advance, the information of the line doubled in the main scanning direction is generated.

In the next step 5, 1 generated in step 4
The image information of the line is copied to the corresponding position of the image buffer area 14 as the image information of the next one line. That is, the double enlargement in the sub-scanning direction is performed by overlapping the image information of one line generated from the scaling change point table.

When the process of step 5 is completed, it is determined whether the process is completed up to the final line (step 6). If there are more lines to process, then steps 4 and 5 are performed for the next line.

When it is determined that the processing of all lines has been completed, the scaling processing is completed and the 2 × magnified image information is obtained in the image buffer area 14.

FIG. 5 shows double-enlarged image information of the input image information shown in FIG. The odd lines of this image information ,, are generated in step 4, and the even lines,
, Are generated by the copy processing in step 5.

The magnified image information thus obtained is output to an image output device, an image recording device, a communication device, etc., which are not shown, but this is not the gist of the present invention and will not be described in detail.

Next, the operation of generating image information reduced to 1/2 times will be described. FIG. 8 is a schematic flowchart of this operation.

In step 7, for every other odd-numbered (or even-numbered) line, the value of the change point table stored in the change point table storage area 6 and the scaling factor (in this case, the scaling factor is 1/2), Is multiplied. The fractional part of the value of the multiplication result is truncated. The change point table after this multiplication is stored in the variable change point table storage area 7 as a variable change point table.

When the scaling change point table for one line is stored, it is determined in step 8 whether processing has been completed up to the final line. If there are remaining lines to be processed, the process of step 7 is executed for the change point table of the next line to be processed.

If it is determined that the last line to be processed has been processed, the process proceeds to the variable-magnification image generation process from step 9.

First, in step 9, the image buffer area 14 is cleared.

In step 10, the image information of one line is generated from the value of the leading scaling change point table stored in the scaling change point table storage area 7, and the image buffer area 14
Is stored in the first line position of. This generation is performed by the same processing as in the case of expansion. Since the number of pixels from the beginning of the line to each change point is halved in advance, information of the line reduced to ½ in the main scanning direction is generated.

When the process of step 10 is completed, it is determined whether the process is completed up to the final line (step 11). If there are remaining lines to be processed, the process of step 9 is executed for the next line.

The process of step 10 is repeatedly executed until the end of step 11 is determined, and the image information of one line is sequentially generated and stored in the image buffer area 14.

Here, the lines to be processed are only odd-numbered (or even-numbered) lines. That is, every other line is thinned out. Therefore, image information reduced to 1/2 in the main scanning direction and the sub-scanning direction is obtained in the image buffer area 14.

Although the image buffer area 5 is used to store both the input image information and the scaled image information in the present embodiment, a buffer area for storing the scaled image information may be separately secured.

In this embodiment, the process of multiplying the value of the change point table by the scaling factor is executed for all the lines to be processed, and then the process of generating the image information from the value of the change point table is executed. The multiplication processing of the change point table and the image information generation processing may be sequentially executed for each plurality of lines.

Further, in this embodiment, the scaling change point table is stored in a storage area different from that of the variation point table, and the variation point table is saved. However, if that is not necessary, the scaling point is stored in the variation point table storage area. A change point table may be stored.

In the present embodiment, processing such as multiplication of the change point table is executed by software, but it may be executed by hardware.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, a scaled image can be obtained only by directly using a change point table that is compressed image information, and thus an image can be obtained using a decoded image. Compared with processing, you can get a scaled image with less memory, shorter processing time and simple structure. In addition, the scaled image obtained by the image creation means is also generated in the form of a compressed change point table, which has the special effect of enabling image processing with even less memory.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram of an image scaling apparatus according to an embodiment of the present invention, and FIG. 3 is a diagram showing an example of input image information. 4 is a diagram showing the contents of a change point table for each line of the input image information shown in FIG. 3, and FIG. 5 is a diagram showing double-enlarged image information of the input image information shown in FIG. FIG. 6 is a schematic flow chart of a 2 × enlargement processing operation, FIG. 7 is a schematic flow chart of a 1/2 reduction processing operation, FIG. 8 is a diagram showing an example of input image information, and FIG. 9 is shown in FIG. It is a figure which shows the 1/2 time reduced image information of the input image information. 1 ... Microprocessor, 2 ... ROM, 3 ... RAM, 5
...... Image buffer area, 6 ... Change point table storage area, 7 ... Variable magnification change point table storage area, 8 ... Line input buffer, 9 ... Buffer address counter,
10 …… Line end detection circuit, 11 …… Change point detection circuit, 12
...... Change point table buffer, 13 ...... Table address counter.

Claims (1)

(57) [Claims] 1. A change point table generating means for generating a change point table representing the number of pixels of a black and white change point from the head of the line for each main scanning line of input image information and storing it in a storage means, and the change point table. And an image generating unit for generating scaling image information based on the value of the change point table after multiplication by this computing unit. .