JP3870101B2 - Image forming apparatus and image forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and an image forming method , and more specifically, to an image forming apparatus and an image forming method for performing drawing based on object data encoded by compression such as image data compressed by packbits. .
[0002]
[Prior art]
Conventionally, various data compression methods have been used to cope with a memory shortage in a printer or to reduce the amount of data created by a host computer to the printer. As one of the data compression methods, for example, there is PackBits compression that performs data compression with a predetermined number of bits as one unit. For example, this corresponds to a byte run length encoding / compression method in which data is compressed by encoding the number of repetitions of the same type of data and different types of data in byte units.
[0003]
[Problems to be solved by the invention]
However, when drawing the object data compressed in the above-mentioned pack bits format, the object data must be expanded from the top. For example, as shown in FIG. 2, a case is considered in which image data having a structure after expansion of 256 bytes × 10 lines is drawn. In the case of 1CLK / 1 Byte processing, if the third line of the data shown in the figure is the drawing start position, if drawing is performed based on the compressed object data, the image data is decoded to the drawing start position. 256 bytes × 2 lines = 512 clocks are required.
[0004]
As described above, when drawing the compressed object data, it takes time to start drawing.
[0005]
The present invention has been made in view of such problems, and an object of the present invention is to provide an image forming apparatus capable of speeding up drawing of compressed object data by performing drawing skipping. And providing an image forming method .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus according to the present invention includes a calculation unit that calculates a drawing start position based on an object width and a drawing start line position, and a code conversion unit that converts an input code into a number of bytes. And adding the number of bytes of the input code converted by the code conversion means to the start address of the object data to obtain an addition value, and then inputting the obtained addition value after being converted by the code conversion means Adding means for obtaining an added value by adding the number of bytes of the generated code, comparing means for comparing the added value obtained by the adding means with the drawing start position calculated by the calculating means, and the comparing means As a result of comparison, the addition value obtained by the addition means is larger than the value of the drawing start position calculated by the calculation means. In this case, the addition value from the address of the code input to the code conversion means and the value of the drawing start position calculated by the calculation means is subtracted from the code at the address immediately before the code input to the code conversion means. And output means for starting the decoding process from the latched address and outputting as drawing data from the number of remaining bytes of the decoded data, as a result of the comparison by the comparison means, When the added value obtained by the adding means is smaller than the drawing start position value calculated by the calculating means, the code converting means converts the next input code into the number of bytes, and the adding means The added value is obtained by adding the number of bytes of the next input code converted by the code converting means to the added value, and the comparing means , And compares the calculated drawing start position by the calculation means and the addition value obtained by said adding means.
[0007]
The image forming method according to the present invention includes a calculation unit that calculates a drawing start position based on an object width and a drawing start line position, a code conversion unit that converts an input code into the number of bytes, and a start of object data. The addition value is obtained by adding the number of bytes of the input code converted by the code conversion means to the address, and the number of bytes of the next input code converted by the code conversion means to the obtained addition value An image executed by an image forming apparatus including an adding unit that calculates an added value by adding, and a comparing unit that compares the added value calculated by the adding unit with the drawing start position calculated by the calculating unit In the forming method, as a result of comparison by the comparison means, an addition value obtained by the addition means is calculated by the calculation means If the value is larger than the value of the drawing start position, the code address input to the code conversion means and the value of the drawing start position calculated by the calculation means are one before the code input to the code conversion means. The number of remaining bytes obtained by subtracting the addition value up to the address code is latched, the decoding process is started from the latched address, and the drawing data is output from the remaining number of bytes of the decoded data. As a result, when the addition value obtained by the addition means is smaller than the value of the drawing start position calculated by the calculation means, the code conversion means converts the next input code into the number of bytes, and the addition means Is obtained by adding the number of bytes of the next input code converted by the code conversion means to the obtained addition value. , The comparing means compares the calculated drawing start position by the calculation means and the addition value obtained by said adding means.
[0021]
In the present invention, the object start address setting register 101 for setting the start address of the Packbits compressed image data object, the object width setting register 102 for setting the object width, the skip line number setting register 103 for setting the number of lines to be skipped, Multiplier 104 that calculates the number of bytes to be skipped from the set value, adder 121 that outputs the address LTOP of the Packbits code portion, and a magnitude comparator that compares the number of bytes calculated from the Packbits code with the number of bytes to be skipped 107 is provided. Accordingly, it is possible to eliminate useless decoding processing by analyzing only the pack bit code portion of the image data subjected to pack bit compression.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023]
FIG. 1 is a block diagram schematically showing an example of a functional configuration of an image forming apparatus to which the present invention is applied, and best represents the features of the invention of the present application. In the figure, the object start address setting register 101 is set with the start address on the memory of the object data compressed in pack bits. In the object width setting register 102, the width of the object data after decoding (decompression) is set. In the skip line number setting register 103, the line number Offset Y of the decompressed object data to be skipped is set. The multiplier 104 multiplies the object width and the number of drawing skip lines to calculate the number of bytes of object data to be skipped.
[0024]
LTOP 105 is an output value from the adder 121. The L T OP105, if the object data is image data that has not been compressed, based on the object width and the number of the skip line, in value when calculating the address to which the writing start position on the object data after decompression is there.
[0025]
The code converter 106 converts the control code (pack bits code) indicating the number of repetitions of the code sequence included in the object data compressed in pack bits into the number of bytes (n) at the time of decoding. The magnitude comparator (MCP) 107 compares the LTOP 105 with the number of bytes (n), and outputs “H” when the number of bytes (n) is large. The subtracter 108 subtracts the number of bytes (n−1) from the LTOP 105.
[0026]
CODE (n) 109 represents the input of a pack bits code. ADR (n) 110 and ADR (n−1) 111 are outputs from the control code position determination unit 122. Of these, ADR (n) 110 is an address indicating the position of the Packbits code, and data input based on this address is CODE (n) 109. ADR (n-1) 111 is an address in the previous state of the address indicated by ADR (n) 110. The remaining byte count 112 is a value calculated by the subtractor 108.
[0027]
The output A113 is a comparison result between the LTOP 105 output from the magnitude comparator 107 and the number of bytes (n). The output B114 is a comparison result between the LTOP 105 output from the magnitude comparator 107 and the number of bytes (n−1).
[0028]
The CODE converter 2 115 calculates the position of the next pack bits code with reference to the current pack bits code on the pack bits compressed object data. Based on the calculated value from the CODE converter 2 115, it is possible to transit from the current pack bits code to the next pack bits code within the compressed object. When 81h to FFh are input as the pack bits code CODE (n) 109, the CODE converter 2 115 outputs 2. When 00h to 7Fh is input as CODE (n) 109, CODE (n) +2 is output.
[0029]
FIG. 2 is a diagram schematically showing an example of a structure after decoding of object data subjected to packbits compression. Data used in the present embodiment is image data having an object width of 256 bytes and a height of 10 lines.
[0030]
In the figure, 2 lines represent the number of lines from the start address to the drawing start position, and LTOP represents the position at which drawing is started. Therefore, the top address of the object data is 40000h, and the address of the drawing start position is 40200h.
[0031]
FIG. 3 is a diagram showing the contents of the pack-bits compressed object data shown in FIG. In the data in the figure, an underlined portion indicates a pack bits code. The code No. indicates the number of pack bit codes in the compressed object data. Here, the code No. 8 and no. A line between 9 indicates that an effective drawing range is entered from a code corresponding to the ninth pack bits code. That is, the code No. The drawing start position is included in the code sequence repeated for the number of bytes specified by the 9 Packbits code. In the example shown in the figure, the 94th byte of data corresponding to code No. 9 is the drawing start position.
[0032]
FIG. 4 is a timing chart of image forming processing executed by the image forming apparatus according to the present embodiment. In the figure, one vertical line break corresponds to one clock.
[0033]
Hereinafter, a case where the object data shown in FIG. 3 is drawn will be described as an example. The start address of the packbits-compressed object data is 40000h, and the object width is 256 (100h) bytes. The height is 10 lines, and the drawing start line position (Offset Y) is 2 lines. In this case, 40000h is set as the object start address in the object start address setting register 101, and 100h is set as the object width in the object width setting register 102. Also, 2h is set as Offset Y in the skip line number setting register 103.
[0034]
In this way, the process of setting the start address of the compressed object data and setting the drawing start position of the decompressed object data is realized. Further, when setting the drawing start position, a process of setting the object width of the decompressed object data and setting the number of lines from the start address to the drawing start position is realized.
[0035]
Accordingly, the number of bytes to be skipped is 256 bytes × 2 lines, for a total of 512 (200 h) bytes, so the output from the multiplier 104 is 200 h. Since the LTOP value is obtained by adding 40000h, which is the object start address set in the object start address setting register 101, to this value, the LTOP output from the adder 121 is 40200h. In this way, the drawing start position is calculated based on the object width and the number of lines.
[0036]
Next, when drawing is started, ADR (n) 110 is output. The value output here is the address 40000h set as the object start address in the object start address setting register 101. As a result, the code No. A pack bits code “81h” corresponding to 1 is input. Then, since the value Num after code conversion by the CODE converter 106 is 128 (80h), the number of bytes (n) is 40080h. Since this value is smaller than the LTOP value, the output A from the magnitude comparator 107 remains “LTOP”. The number of bytes Num from the current pack bits code output from the CODE converter 2 115 to 2 is 2, and the address ADR (n) 110 after code conversion is 40002h. Therefore, at the next clock, the code No. The next Packbits code “02h” corresponding to 2 is input to the CODE converter 106 and the CODE converter 2 115.
[0037]
Next, the same processing as described above is performed, the number of bytes (n) becomes 40083h, and ADR (n) 110 becomes 40006h.
[0038]
After the above processing is repeated, the code No. When the process proceeds to 8, ADR (n) 110 becomes 4001Dh, and the number of bytes (n) becomes 401A3h. In the next clock, the code No. specified in ADR (n) 110 is set. When the pack bit code “81h” corresponding to 9 is input, the number of bytes (n) is 40223h, which is larger than the LTOP value (= 40200h). At this time, the output A becomes “H” and the output B becomes “L”, and the ADR (n−1) 111 and the remaining number of bytes 112 are latched at this timing.
[0039]
The address of the ADR (n−1) 111 latched in this way is the position of the pack bits code including the data of the drawing start position (LTOP). Accordingly, the latch process realizes a process for determining the position of the control code in the compressed object data corresponding to the set drawing start position based on the set start address.
[0040]
The number of remaining bytes 112 indicates the number of bytes from the position of the determined control code to the drawing start position, and from which byte in the code sequence specified by the Packbits code is valid drawing data Is a pointer indicating
[0041]
That is, in the present embodiment, when printing object data compressed in pack bits, the decoding process is started from the address 4001Dh of the pack bits code shown in the example of FIG. As a result, drawing data is output from the 94th byte of the decoded number of bytes.
[0042]
Therefore, in the past, it took 512 clocks to decode the packbits-compressed object data to the drawing start position, whereas according to the image forming method according to the present embodiment, the same data is drawn in about 94 + 9 clocks. Can start. As a result, image data can be printed at a higher speed.
[0043]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be implemented in various other forms.
[0044]
In the present invention, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus stores the storage medium. Needless to say, this can also be achieved by reading and executing the program code stored in.
[0045]
In this case, the program code itself read from the storage medium realizes the novel function of the present invention, and the storage medium storing the program code constitutes the present invention.
[0046]
As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, a hard disk, a magneto-optical disk, an optical disk, a CD-ROM, a CD-R, a magnetic tape nonvolatile memory card, a ROM, or the like is used. Can do.
[0047]
In addition, the functions of the above-described embodiments are realized by executing the program code read by the computer, and the OS running on the computer is one of the actual processes based on the instruction of the program code. The functions of the above-described embodiment can be realized by performing some or all of the processes.
[0048]
Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. The CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments can be realized by the processing.
[0049]
It goes without saying that the present invention can also be applied to the case where the program is distributed to a requester via a communication line such as personal computer communication from a storage medium that records the program code of software that implements the functions of the above-described embodiments. Yes.
[0050]
【The invention's effect】
As described above, according to the present invention, the drawing start position is calculated based on the object width and the drawing start line position, the input code is converted into the number of bytes, and the input address converted into the start address of the object data is input. The added value is obtained by adding the number of bytes of the obtained code, and the added value is obtained by adding the number of bytes of the next input code converted into the obtained added value, and the obtained added value and calculation are calculated. If the calculated addition value is larger than the calculated drawing start position value, the input address of the input code and the calculated drawing start position value are input. The number of remaining bytes obtained by subtracting the added value up to the code at the address immediately before the code is latched, and decoding is started from the latched address. If the calculated addition value is smaller than the calculated drawing start position value, the next input code is converted to the number of bytes and added. The addition value is obtained by adding the number of bytes of the next input code converted to the addition value obtained at the time of comparison, and the addition value obtained at the time of comparison is compared with the calculated drawing start position. since, when performing the line skip image data packbit compressed, so that the need without decoding of lines to be skipped. As a result, high-speed drawing processing can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically illustrating an example of a functional configuration of an image forming apparatus to which the present invention is applied.
FIG. 2 is a diagram schematically illustrating an example of a structure after decoding of pack-bits-compressed object data.
FIG. 3 is a diagram showing the contents of pack-bits-compressed object data shown in FIG.
FIG. 4 is a timing chart of image forming processing executed by the image forming apparatus according to the embodiment of the invention.
[Explanation of symbols]
101 Object start address setting register 102 Object width setting register 103 Skip line number setting register (Offset Y)
104 Multiplier (Skip byte number calculation)
105 LTOP
106 CODE Converter 107 Comparator 108 Subtractor 109 Pack Bits Code 110 Pack Bits Code Position Address (n)
111 Packbits code position address (n-1)
112 Number of remaining bytes 113 Output A
114 Output B
115 CODE converter 2
121 Adder 122 Control Code Position Discrimination Unit

Claims (2)

Calculating means for calculating a drawing start position based on the object width and the drawing start line position;
Code conversion means for converting the input code into the number of bytes;
An addition value is obtained by adding the number of bytes of the input code converted by the code conversion means to the start address of the object data, and then input to the obtained addition value after being converted by the code conversion means. Adding means for obtaining an added value by adding the number of bytes of the code;
Comparing means for comparing the addition value obtained by the adding means with the drawing start position calculated by the calculating means;
As a result of the comparison by the comparison means, when the addition value obtained by the addition means is larger than the value of the drawing start position calculated by the calculation means, the address of the code input to the code conversion means, and the calculation means The number of remaining bytes obtained by subtracting the addition value from the value of the drawing start position calculated by the code to the code of the address immediately before the code input to the code conversion means is latched, and decoding processing is performed from the latched address Output means for outputting as drawing data from the number of remaining bytes of the decoded data,
As a result of the comparison by the comparison means, if the addition value obtained by the addition means is smaller than the drawing start position value calculated by the calculation means, the code conversion means converts the next input code into the number of bytes. The adding means obtains an added value by adding the number of bytes of the next input code converted by the code converting means to the obtained added value, and the comparing means obtains the added value by the adding means. An image forming apparatus, wherein the added value is compared with the drawing start position calculated by the calculating means. Calculation means for calculating the drawing start position based on the object width and the drawing start line position, code conversion means for converting the input code into the number of bytes, and input converted by the code conversion means to the start address of the object data Adding means for obtaining an added value by adding the number of bytes of the code obtained, and adding the number of bytes of the next input code converted by the code converting means to the obtained added value And an image forming method executed by an image forming apparatus having a comparison unit that compares the addition value obtained by the addition unit with the drawing start position calculated by the calculation unit,
As a result of the comparison by the comparison means, when the addition value obtained by the addition means is larger than the value of the drawing start position calculated by the calculation means, the code address input to the code conversion means and the calculation means The number of remaining bytes obtained by subtracting the added value from the calculated drawing start position value to the code at the previous address of the code input to the code conversion means is latched, and decoding is started from the latched address. And output as drawing data from the remaining bytes of the decoded data,
As a result of the comparison by the comparison means, when the addition value obtained by the addition means is smaller than the drawing start position value calculated by the calculation means, the code conversion means converts the next input code into the number of bytes. The addition means obtains an addition value by adding the number of bytes of the next input code converted by the code conversion means to the obtained addition value, and the comparison means obtains the addition value by the addition means. An image forming method, comprising: comparing the obtained addition value with a drawing start position calculated by the calculating unit.

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