JP3636891B2 - Color image output method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to color image output processing, and more particularly to a color image output method for performing raster processing in a PDL (Page Description Language) interpreter, and is applied to a controller device such as a color printer or printer driver software installed in a computer. Technology.
[0002]
[Prior art]
In general, when a document created by a computer is output to a printer, the following procedure is used. That is,
(1) Convert document data into a plurality of drawing command groups.
(2) A raster image is created by analyzing a drawing command by software called a printer driver or a printer controller (generally, the above processing is called a raster operation).
(3) A color conversion process or pseudo halftone process is performed on the raster image to generate a printer output signal.
(4) Execute printing.
[0003]
By the way, in order to output a preferable color image, different color processing and halftone processing are required depending on the type of image, such as a natural image, characters, and graphics. Therefore, in order to output color image information including various image types, an architecture capable of performing image processing suitable for each image type is required.
[0004]
As a conventional technique for outputting such color image information,
(A) A method for preparing a bitmap memory for each image type and individually creating a raster image;
(B) There is a method in which after a raster image is generated, the raster image is scanned to determine the attribute for each pixel (see, for example, Japanese Patent Laid-Open No. 9-284548).
[0005]
[Problems to be solved by the invention]
In the method (A) described above, since a memory for storing a raster image is prepared for each image type, there is a problem that a large amount of memory is wasted if the number of image types to be distinguished increases. Also, the PDL interpreter that performs the raster operation must be significantly changed, which makes it difficult to change the raster operation processing method.
[0006]
In the method (B), since the image area separation is performed using the raster image, there is a problem that erroneous determination is likely to occur. Since the above-mentioned gazette also performs image separation processing in units of 3 × 3 pixels, there is a possibility that erroneous determination occurs.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a color image output method for performing raster processing by identifying image types with high memory efficiency and without modifying an existing PDL interpreter.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the document image described by the drawing command is developed into a bit image, and the image type of the document image is determined for each drawing command, and the determination is made. A color image output method for assigning a predetermined code to the image type, developing a code representing the image type into a bit image, and performing an optimum process on the document image according to the image type, When the drawing command is a command for performing an operation between a plurality of image types, a new code is assigned to an area where the operation command is executed, and the bit image is developed .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
(Example 1)
FIG. 2 is an example of a color image including various graphics. This image includes a natural image (bitmap), font (character), line drawing, single color fill pattern (bar graph), and the like in one document. Hereinafter, an embodiment of the present invention will be described with reference to a case where this image is printed.
[0010]
FIG. 1 shows a configuration of a first embodiment of the present invention, which is a system configuration example when a raster operation is performed in a printer controller. Usually, the operating system 2 includes a dedicated module 3 for drawing, and this drawing module 3 manages drawing processing for a display and a printer.
[0011]
For example, when a document image as shown in FIG. 2 edited by the operator on the screen using any application 1 is printed on a printer, the application 1 transmits a command to start a print job to the drawing module 3. Upon receiving a print start message, the drawing module 3 converts the document image data created by the application 1 into a command that can be interpreted by the printer driver 4, and transmits the command to the printer driver 4.
[0012]
The printer driver 4 converts the command received from the operating system 2 into a drawing command that can be interpreted by the printer controller 5 and transmits the command to the printer controller 5 connected locally or over the network. The printer controller 5 converts the data into data that can be transmitted to the printer 12 by a raster operation and image conversion means described later, and starts a printing operation. When printing is completed, the application 1 transmits a print end command to the drawing module 3 so that the operator can edit again.
[0013]
Next, raster operation processing, which is a feature of the present invention, will be described. FIG. 4 is a processing flowchart of the raster operation of the present invention.
[0014]
The drawing command sent from the printer driver 4 is composed of a number of drawing commands corresponding to the image type. Usually, this drawing command includes information such as the type of image to be drawn (for example, bitmap, character, line, pattern, etc.), shape, position information, and color data. For example, as a character drawing command, DrawText ("Home Computing ...", rect, color)
Command form. Here, “Home Computing...” Represents the contents of the text document to be drawn, “rect” represents the area on the bitmap to be drawn, and “color” represents the drawing color. A command group suitable for each of other image types such as a bitmap is sent.
[0015]
The raster operation for the above drawing command is processed in two systems. One is a general raster operation. The raster development apparatus 7 faithfully performs a development process (RIP (Raster Image Processor) process) in accordance with a drawing command (step 101), and the generated raster image is stored in the bitmap memory 8. Store in (A) (step 102).
[0016]
The other is raster development for identifying image types. That is, the color data of the drawing command is converted into an image type identification code by the command conversion device 6 and then developed by the same raster development device 7 as the previous raster operation, and the generated image is stored in the bitmap memory 9 (B ). In this method, since the first raster development and the second raster development are processed in synchronism, by referring to the bitmap memory B, it is possible to identify an image type without erroneous determination for each pixel.
[0017]
The processing operation of the present invention will be described below with reference to FIG. Here, for convenience of explanation, an identification code for each image type is assigned and explained as follows. That is,
Background = 0
Character = 1
Line = 2
Rectangle = 3
Bitmap = 4
Other = 5
First, in order to identify an area where no drawing is performed, the contents of the bitmap memory 8 (B) are initialized with the background identification code 0 at the start of the raster operation.
[0018]
After that, the raster code is executed by assigning an identification code for each drawing command. As shown in FIG. 4, the command conversion device 6 first determines whether or not the drawing command is for a character (step 103). If it is a character, the color data of the drawing command is changed to 1 which is the character identification code ( In step 110), the raster development device 7 executes raster development (step 108), and stores the image type code in the bitmap memory 9 (B) (step 109).
[0019]
If it is determined that the character is not a character, it is next determined whether or not the command is a line drawing command (step 104). If it is a line drawing, the color data is changed to 2 which is a line identification code (step 111). The data is expanded (step 108) and stored in the bitmap memory 9 (B) (step 109). Thereafter, a rectangular drawing command is processed in the same manner (steps 105 and 112), a bitmap drawing command is processed (steps 106 and 113), and if none of the above commands is applicable, a default identification code 5 Is assigned (step 107).
[0020]
How the contents of the bitmap memory B change by the above processing will be described with reference to FIG. In FIG.
Three drawing commands are executed: (1) drawing a bitmap (2) drawing characters (3) drawing a bitmap.
[0021]
In the first stage (FIG. 5A), 0 representing the background code is assigned to the bitmap memory B. Next, when the bitmap drawing is performed, the entire bitmap drawing area is rewritten to the identification code 4 (FIG. 5B). Next, when a character drawing command is received, since raster development is performed by changing the color data to 1, only the character portion is drawn with a color having a value of 1, so that FIG. become that way. When the next bitmap drawing command is received, the same processing as described above is performed, and the contents of the bitmap memory B are updated as shown in FIG.
[0022]
As described above, in this embodiment, the image type identification code can be accurately generated on the bitmap memory even if the drawing objects overlap each other in a complicated manner. Further, the bitmap memory B does not necessarily have the same storage capacity as the bitmap memory A. For example, in the above example, since there are six types of image type identification codes, a memory of 3 bits per pixel may be prepared.
[0023]
When the above-described processing is applied to the document data of FIG. 2, an image composed of the image type identification codes as shown in FIG.
[0024]
In the above-described embodiment, six types of allocation patterns are used. However, the pattern is not limited to this example, and patterns of characters and other patterns may be used, or other patterns may be used. However, since preferable image conversion processing is clearly different at least between characters and bitmaps, it is desirable to assign different identification codes to these two image types.
[0025]
When a bitmap holding an image type identification code is generated by the above-described processing, an image conversion process is performed on the bitmap memory A while discriminating the image type in accordance with this, and an output signal to the printer is generated. The image stored in the bitmap memory A is an RGB signal having a color depth of about 24 bits (or 8 bits) for each pixel as in the normal display. Since a printer is generally printed with other color signals (usually CMYK data), color conversion processing such as RGB → CMYK conversion is required. Further, many ordinary color printers such as an ink jet printer have fewer gradations than a display, and in such a case, pseudo halftone processing is required. The image conversion process of the present embodiment is not limited to the color conversion process and the pseudo halftone process described above, and other processes may be added.
[0026]
As an example of optimization processing, a case of RGB → CMYK color conversion will be described. In general, in RGB → CMYK color conversion, black characters are output using only black ink, and the black portion of a continuous tone image such as a natural image is color-converted so that it is printed with four colors of CMYK. Desirable to see. Therefore, when color conversion is performed by the color conversion processing device 10, the bitmap memories A and B are read out in units of pixels, the pixels having the bitmap codes are converted into four colors, and the characters are converted. For pixels having the above code, color conversion is performed so that a single black color is output. Also, with regard to halftone processing in the binarization processing apparatus 11, dither processing is performed for characters and error diffusion processing is performed for bitmap areas, thereby enabling optimization processing for each image type.
[0027]
Further, according to the present invention, 0 is assigned as the background identification code for the background portion that is not drawn. Therefore, special processing can be performed only on the background area. For example, since normal printing is not performed on the background area on the printer side, color conversion processing and halftone processing are not performed on pixels for which a background code is set, and C, M, Y, If data is transmitted to the printer with K = 0, a high-speed printing operation can be performed.
[0028]
Further, as a more complicated example, there is a case where arithmetic processing or the like is performed between a plurality of drawing objects. For example, there is a case where a bitmap is drawn on a lower layer, and a character with transparency is drawn on the bitmap. In such a case, since transparency is set for the character, the character and the background bitmap image are displayed lightly mixed on the screen. In such a case, it is necessary to set a new image type that is different from characters and bitmaps. Therefore, when a calculation instruction between layers is received, a new identification code representing the calculation area is set. By setting such a code, optimization such as color conversion processing can be easily performed.
[0029]
(Example 2)
The first embodiment described above is an embodiment in the case where a raster operation is performed in the printer controller. By the way, in an inexpensive ink jet printer or the like, the raster operation is not performed in the printer controller, the raster operation is performed by the printer driver, and the data is expanded into a bitmap image and then transmitted to the printer. FIG. 6 shows a configuration example in this case.
[0030]
In the first embodiment, processing such as raster operation is performed by a device in the controller. However, in the second embodiment shown in FIG. 6, each processing such as command conversion and raster development is performed by software of a printer driver (command conversion module or the like). The basic processing contents are the same as those of the first embodiment except that the processing is performed in each module.
[0031]
The present invention is not limited to the above-described embodiments, and the above-described printer driver software may be recorded on a recording medium such as a CD-ROM. When executing the raster operation of the present invention, the processing function of the present invention is realized by reading the program recorded on the recording medium and incorporating it as a part of the OS.
[0032]
【The invention's effect】
As described above, according to the present invention, as well as expand the document image to be described by the rendering instruction bit image, since developed an identification code of the image type in bit image, to modify the PDL interpreter Therefore, it is possible to identify the image type with a small amount of memory and with high accuracy, and therefore it is possible to perform optimum image processing according to the image type.
[Brief description of the drawings]
FIG. 1 shows a configuration of Embodiment 1 of the present invention.
FIG. 2 shows an example of a document image composed of a plurality of image types.
FIG. 3 shows an example of an image type determination result for a document image.
FIG. 4 is a processing flowchart of a raster operation according to the present invention.
FIG. 5 shows a process in which an image type identification code is written in a memory.
FIG. 6 shows a configuration of Embodiment 2 of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Application 2 Operating system 3 Drawing module 4 Printer driver 5 Printer controller 6 Command conversion device 7 Raster development device 8, 9 Bitmap memory 10 Color conversion processing device 11 Binarization processing device 12 Printing device

Claims (1)

The document image described by the rendering command is developed into a bit image, the image type of the document image is determined for each rendering command, a predetermined code is assigned to the determined image type, and the image type is represented A color image output method in which a code is expanded into a bit image, and an optimum process according to the image type is performed on the document image for output. The drawing command is a command for performing an operation between a plurality of image types. A color image output method characterized in that a new code is assigned to a region for executing the operation instruction and developed into a bit image.

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