JPH03216361A - Printer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus that synthesizes and outputs image data stored in a plurality of types of image memories having different resolutions.

[Prior Art] In the following description, an image consisting only of characters will be referred to as a "character image", and an image such as a photograph or a painting will be referred to as an "image image".

In addition, when an image is expressed as a collection of pixels, and each pixel can express several types of shading, the pixel density is
``resolution'' and the type or degree of ``gradation''.

In general, when the amount of memory for storing image information is limited and therefore resolution and gradation are limited, resolution and gradation are in a trade-off relationship with each other. For example, the memory capacity of a memory that stores image data with a resolution of 600 dpi without gradation (binary on/off),
Memory capacity for storing image data with a resolution of 300 dpi at 16 gradations, and 150 dpi at 256 gradations.
The memory capacity of the memory that stores image data of resolution is equal.

Because of this relationship, conventionally there are devices configured to store character images and image images in separate image memories with different resolutions in order to obtain high-quality output results with a small amount of notes. For example, the character image memory has a resolution of 600 dpi with no gradation, and the image image memory has a resolution of 64 dpi.
This device has a gradation resolution of 150 dpi.

This is because text images generally require a higher resolution than image images, and images, on the other hand, appear to have higher quality to the naked eye if they have a certain degree of gradation.

In the conventional device, with the above configuration, all characters are drawn in the character image memory, image images are drawn in the image image memory, and when outputting, they are overlapped and output, so that only the character image part can be written with the minimum memory capacity. High quality output can be obtained for both the image part and the image part.

[Problems to be Solved by the Invention] However, such conventional devices do not have a problem when the text image area and the image image area are separated, but the problem is that the text is output by superimposing the text on top of the image. In such a case,
In the case of cutting out the inside of an image in the shape of a letter, or in the case of filling the inside of a letter with an image (cribbing the image with a letter link), the difference in resolution between the two images becomes a problem.

That is, a gap may appear at the outline of a character or a boundary between a character and an image, resulting in an unnatural image.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above-mentioned problems, and includes the following configuration as one means for solving the above-mentioned problems.

That is, there is a character image memory that stores character image data without gradation, an image memory that stores image data that has gradation and whose resolution is coarser than that of the character image data, and an image memory that stores image data that has gradation. A determining means for determining whether to draw on the memory or character image memory, a conversion drawing means for approximately drawing the image image data on the character image memory, and a conversion drawing means for drawing the image data by approximating it on the character image memory; and output means for synthesizing and outputting the image data as necessary.

[Effect] With the above configuration, the difference in resolution between the two images no longer becomes a problem, and the outlines of characters become unnatural, and gaps appear at the boundary between characters and images. This will prevent it from becoming an image.

[Example] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block configuration diagram of an embodiment according to the present invention, and in the figure, reference numeral 1 denotes a printer 2 which is an image forming apparatus of this embodiment.
A host computer 2 is a printer in this embodiment for controlling the printer and transmitting data to be printed.

In the printer 2, a CPU 3 is stored in the ROM 6 and controls the entire printer 2 according to the control procedures shown in FIGS. 4 and 6, which will be described later. 4 is a CPU for creating and storing character images. 5 is a character image memory for creating and storing image images, 6 is a ROM in which the above-mentioned programs etc. are stored, and 7 is a character image video signal line for transferring character images to the output unit 9. ,
Reference numeral 8 indicates a character image video signal line for transferring the image image to the output section 9, and reference numeral 9 indicates an output for forming a visible image on recording paper according to the video signals sent via the signal lines 7 and 8. Department.

The output unit 9 can express each image pixel on the paper at each gradation.

The character image memory 4 is a bitmap memory with a capacity to store one page worth of character images, and has a capacity of 1 page per pixel.
By allocating bits, one pixel is represented as black and white by turning one bit on or off.

The image memory 5 is a byte map memory with a capacity to store one page worth of images, and one byte is allocated per pixel, and one pixel is divided into 25 of 0 to 255.
Expressed in 6 gradations.

In this embodiment having the above configuration, the image image has a resolution of 150 dpi, and the character image has a resolution of 600 dpi.

FIG. 2 shows the difference in size between image pixels and character pixels due to this difference in resolution.

As shown in Figure 2, pixel 21 of a 150 dpi image
is the size of 16 pixels 22 of a 600 dpi character.

Because the resolution of the character image and the image image are different in this way, the size of the character pixel and the image pixel are different, so if the two images are combined as they are, the outline of the character as shown in Figure 3 will be different from the image pixel. 1 to cross the inside of
A situation may occur in which an image portion and a character portion coexist within a surface occupied by one image pixel.

In such a case, in order to obtain a good composite output image, in this embodiment, for example, image composition processing shown in FIG. 4 is performed. FIG. 4 is a flowchart showing a process for cribbing an image with the outline of a character (cutting an image into the shape of a character) as an example. Process.

First, in step S1, it is determined whether the corresponding pixel is completely inside the character boundary. If the pixel does not straddle the character boundary and is completely inside the boundary, proceed to step S2;
The image is drawn in the image memory 5.

On the other hand, if the corresponding pixel is not completely inside the character boundary, the process proceeds to step S3, and it is determined whether the pixel is completely outside the character boundary. If it is outside, that pixel is cribbed and does not form an image, so processing for that pixel ends without drawing.

On the other hand, if the corresponding pixel is not completely outside the character boundary in step S3, the pixel will straddle both inside and outside the character outline, and the process proceeds to step S4, where the image is clipped with the outline of the character image. Process.

In this embodiment, at this time, the image data of the pixel area is drawn not in the image memory 5 but in the character image memory 4.

The mechanism will be explained with reference to FIGS. 5(A) to 5(F).

As described above, the area of one image pixel includes 16 character pixels. In addition, the image image is 25 colors other than white.
Captures 5 types of gradations.

Therefore, in this embodiment, the gradations from "1" to "16"
'', the character image memory 4 is blackened by one dot as shown in FIG. 5(A).

If the gradation is from "17" to "32",
As shown in FIG. 5(B), the character image memory 4 for two dots is made black.

If the gradation is from "33" to "48",
As shown in FIG. 5(C), the character image memory 4 for 3 dots is blackened.

If the gradation is from "49" to "64",
As shown in FIG. 5(D), 4 dots of character image memory 4 are made black.

Thereafter, the number of dots to be made black in the character image memory 4 is sequentially increased every time the gradation level increases by 16, and the gradation level reaches r.
If the image is from 223J to r240J, the character image memory 4 for 15 dots will be blackened as shown in Figure 5(E), and if the image is from r241J to r255J, the character image memory 4 will be blackened as shown in Figure 5(F). As shown below, by making all 16 dots of character image memory 4 black, 255 gradations can be changed to 16
Approximate the gradation.

Please refer to the flowchart in FIG. 6 for details of the process in step S4 in FIG. 4 when the image image is clipped using the outline of the character image at the gradation shown in FIG. 5 (cutting the image image into the shape of the character image). and will be explained below.

First, in step S5, it is determined whether the gradation of the pixel is rOJ. If it is rOJ, there is no need to draw it, so the process ends.

If the gradation of the pixel is not rOJ, the process proceeds to step S6, and it is determined whether the gradation is between rlJ and "16". If the number is between "1" and "16", the process advances to step S7, and if the dot to be blackened is inside the character boundary, one dot is blackened at the corresponding position in the character image memory.

If the gradation of the pixel is not between "1" and "16", the process proceeds to step S8, and it is determined whether the gradation is between "17" and "32". If it is between "17" and "32", the process advances to step S9, and if the dot to be black is inside the character boundary, the dot at the corresponding position in the character image memory inside the character boundary (maximum 2 dots) Make it black.

If the gradation of the pixel is not between "17" and "32", the process proceeds to step SIO, and it is determined whether the gradation is between "33" and "48".

If it is between "33" and "48", the process advances to step S11, and if the dot to be made black is inside the character boundary, the dot at the corresponding position in the character image memory inside the character boundary (maximum 3 dots) Make it black.

Thereafter, the character image memory 4 is similarly turned black according to the gradation, and the gradation of the pixel shown in step SL2 is r2 2
The gradation is determined between 3J and r240J, and the gradation is r2.
If the value is between 23J and r240J, the process proceeds to step S13, and among the dots to be blackened, the dots (maximum 15 dots) at corresponding positions in the character image memory that are inside the character boundary are blackened.

On the other hand, if the gradation is r241J or higher, step S14
Then, among the dots to be made black, the dots at the corresponding positions in the character image memory that are inside the character boundaries are made black.

FIG. 7 shows an example in which image data is drawn not in the image memory 5 but in the character image memory 4 only inside the character boundaries as described above.

In this way, by sequentially blacking out only the dots at the corresponding positions in the character image memory inside the character boundary, image disturbances due to the difference in resolution between the character image and the image image will not occur. , high quality images can be obtained.

Furthermore, being able to synthesize buffers with different resolutions can save memory capacity and reduce manufacturing and product costs.

[Other Embodiments] In the above description, an example was given in which image data is drawn only inside the character boundary in the character image memory 4 instead of the image image memory 5, but the present invention is not limited to this. Various applications can be considered, such as writing images on the outside of letters, cutting out the inside of images in the shape of letters, etc. Naturally, the present invention also includes approximating the resolution using these drawing methods.

Further, in the above explanation, character image data is written to the character image memory 4, and image image data is written to the character image memory 4 instead of the image image memory 5 using the logical sum method, but this is limited to an example of writing the logical sum. It's not a thing《,
Only one of the data, such as character image data, may be written, or may be written using other methods.

[Effects of the Invention] As explained above, according to the present invention, it is possible to prevent the outline of characters from becoming unnatural or the appearance of gaps between characters and images, resulting in unnatural images. Gone,
It is possible to obtain a high-quality output image in which the difference in resolution between the character image and the image image does not pose a problem.

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram of an embodiment according to the present invention, Fig. 2 is a diagram for explaining the sizes of image pixels and character pixels due to the difference in resolution in this embodiment, and Fig. 3 is a diagram of the character A diagram illustrating a situation in which both images are combined as they are, and image portions and text portions are mixed. Figures 4 and 6 are image compositing processing for combining character images and image images in this embodiment. FIGS. 5(A) to 5(F) are diagrams for explaining a drawing method for drawing image data of an area of overlapping pixels in the character image memory in this embodiment, and FIG. 7 is a flowchart showing this embodiment. FIG. 3 is a diagram showing an example of image data drawn using the drawing method of FIG. In the figure, 1... host computer, 2... printer 3... CPU, 4... character image memory, 5... image image memory, 6... ROM, 7... character image video Signal line, 8... Character image video signal line, 9...
・It is an output section. ? Stop 1/2 Figure 3 Figure 4 Figure Kinuta 1 to 16 (A) gl17 to 32 (B) rden A~48 (C) g149 4 (D) Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A character image memory that stores character image data without gradation, an image image memory that stores image image data that has gradation with coarser resolution than the character image data, and an image image memory that stores the image image on the image image memory. a determining means for determining whether to draw or draw on the character image memory; a conversion drawing means for approximately drawing the image image data on the character image memory; and storage in the image image memory and the character image memory. 1. A printing apparatus comprising: output means for synthesizing and outputting image data as required.