JPH05323908A - Display controller - Google Patents

Abstract

PURPOSE:To enable high picture quality display. CONSTITUTION:The display controller is provided with an image area information generating means 203 generating image area information indicating an area displaying binary image data obtained by executing image processing to the image data of a multilevel frame buffer and an area displaying binary image data obtained by executing approximate color converting on a screen based on the software of a computer and a processing means 209 processing the image data based on the image area information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display control device for displaying a mixture of a character image and an image image on a screen, and particularly to a display using a ferroelectric liquid crystal (FLC). The present invention relates to a display control device that controls a device.

[0002]

2. Description of the Related Art A display using a ferroelectric liquid crystal is
In the current technology, each pixel can be in only two states of lighting and non-lighting due to the physical reason of the liquid crystal. As a method of displaying intermediate colors on a display having such a digital property, an area gradation method, that is, dividing each pixel into a plurality of sub-pixels having an appropriate area ratio and applying a color filter to each sub-pixel There is something. According to this, assuming that the number of sub-pixels per pixel is n, the maximum is 2
It is possible to display the nth power color of. For example, one pixel is R
When the sub-pixel is composed of four sub-pixels (red), G (green), B (blue), and W (white), the number of displayable colors is 16.

However, as is apparent from the current computer market, display devices tend to be required to have higher color display capability in the future. In particular, when the field of applications using multimedia technology, such as moving image capture and compound documents in which natural images and texts are mixed, is actively used, a large number of displayable colors becomes indispensable. In such a situation, the number of display colors is limited only by the intermediate color display using the above-described area gradation, and it is difficult to satisfy the demand of the application as described above.

Therefore, each pixel (minimum display unit) has a digital display (hereinafter, such a display will be referred to as a "binary display").
In order to obtain higher color expression in, a method of introducing a method of image processing has been devised. This is a multi-valued frame buffer that is often used for color displays-for example, it is subjected to image processing such as the error diffusion method of image data of 8 bits / pixels, and the processed data is displayed on a binary display. is there. As a result, a higher color expression can be visually obtained on a display having a limited number of display colors as a device.

[0005]

However, the conventional image display device incorporating the image processing method has the following problems. It is effective when a high color expression is visually obtained by the image processing method, and when the target image data includes many intermediate colors such as a natural image such as a photograph, but it is effective like a character output screen of a computer. If the image is a simple digital image with a clear contour and is displayed in an intermediate color, the contour becomes rather ambiguous and the visibility of characters and the like is likely to deteriorate.
This is because the conventional method collectively performs image processing on the entire screen without considering the property of the image data.

Therefore, an object of the present invention is to provide a display control device capable of obtaining a high quality display image.

[0007]

In order to solve the above-mentioned problems, the present invention provides an area for displaying binary image data obtained by performing image processing on image data of a multi-valued frame buffer on a screen, Image area information generating means for generating, based on software of a computer, image area information designating an area in which binary image data obtained by performing approximate color conversion is displayed, and the data is processed based on the image area information. And a processing means.

[0008]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the entire image display system including the image display device of the present invention. In FIG. 1, 101 is a central processing unit of a host computer, 102 is a main memory, 103 is a keyboard and mouse interface, 104 is a keyboard and mouse, 105 is a system bus, 106 is a hard disk controller, and 107 is A hard disk drive, 108 is a network interface, and 109 is a network. Further, 110 is an external image input interface, which receives 111 external image input,
8-bpp frame buffer (8 bit / pixel
Image data is written in a predetermined area in l). 112
Image data is also written in the 8-bpp frame buffer in response to a command from the 101 central processing unit. 11
The 3 palettes convert pixel data in the 112 8-bpp frame buffer image (image data unit that specifies color display of one pixel of the display) into color data to be displayed on the display. 114 The binarization circuit selection switch sets the color data received from the 113 palette to 11
5 Transfer to the approximate color conversion circuit or 116 image processing logic circuit as appropriate. The 115 approximate color conversion circuit approximately converts the color data generated by the 113 palette into a color that can be displayed on the 118 FLC display, and transfers the color data to the 117 binarized frame buffer. 116 image processing logic circuit is 112 8-bp
The pixel data in the p frame buffer is subjected to image processing after being passed through the 113 palette, and is transferred to the 117 binarized frame buffer. The 117 binarization frame buffer is a frame buffer having bits corresponding to the sub-pixels of the 118FLC display in a one-to-one correspondence. The 118FLC display is a display device using a ferroelectric liquid crystal. The 119 image area description table is 112 8-bpp (bit per pixel).
1) A table describing a region to be subjected to image processing and a region to be subjected to approximate color conversion when binarizing the data in the frame buffer. 120 the binarization control circuit is 119
Based on the image area description table, it controls the 114 binarization circuit selection switch, the 116 image processing logic circuit, and the data to be transferred from the 112 multi-valued frame buffer to the 113 palettes. 121 Output line information buffer is 1
01 stores information related to writing to the 112 8-bpp frame buffer, which is transferred from software operating in the central processing unit. The 122 output line control circuit appropriately reads the image information from the 117 binarization frame buffer based on the information in the 121 output line information buffer and transfers it to the 118 FLC display for display.

FIG. 2 is a diagram showing a logical configuration of the present invention. The 201 graphic software has a 202 drawing unit that writes image information in a 206 multi-valued frame buffer. This 206 multi-level frame buffer has 2
12 stores image information that is a source of an image to be displayed on the display. The 207 palette converts the image information in the 206 multi-valued frame buffer into color information as an index of the color table, or if the 206 multi-valued frame buffer stores the color information itself, converts it into 208 binarization. Transfer to the circuit switching unit. on the other hand,
The 201 graphic software generates a 202 image area information generation unit that generates information that defines an area to be displayed after image processing conversion or an approximate color conversion among the information written in the 206 multi-valued frame buffer. have. This information is temporarily stored in the 204 image area information storage unit. Further, the 205 binarization control unit refers to this to transfer the multivalued image information from the 206 multivalued frame buffer to the 207 palette for each area, and at the same time, control the 208 binarization circuit switching unit from the 207 palette. It is determined whether to transfer the output information to the 209 image processing unit or the 210 approximate color conversion unit. 209 Image processing unit and 2
The 10-approximate color conversion unit generates binarized image information from the transferred information and stores it in the 211 binarized frame buffer. The binarized image information stored in the binarized frame buffer 211 is sequentially transferred and displayed on the display 212.

In FIG. 2, 201 graphics software is placed in 102 main memory of FIG. 1 and executed by 101 central processing unit. In addition, the 204 image area information storage unit stores 205 according to the 119 image area description table.
The binarization control unit 120 uses the binarization control circuit 208
The binarization circuit switching unit is realized by 114 binarization circuit selection switch, the 209 image processing unit is realized by 116 image processing logic circuit, and the 210 approximate color conversion unit is realized by 115 approximate color conversion circuit.

Next, how the logic configuration shown in FIG. 2 is implemented in the embodiment of FIG. 1 will be described in more detail.

First, 201 graphic software is an X window server (hereinafter abbreviated as X server) (X or X Wi) executed by 101 central processing unit in 102 main memory in FIG.
The Windows System is Massachusett
s Institute of Technology
Is a registered trademark of. As is well known, the X window system refers to the entire system including a plurality of application programs called a client, and a program called a server which processes drawing requests from clients and actually draws them in a frame buffer. The server and the client operate by communicating with each other based on the protocol called X Pro Turkey. FIG. 3 shows the outline of the internal processing of the X server.
In step 301, the presence or absence of a hardware event, that is, keyboard input or pointer operation by the user is checked, and if any, it is processed in step 302.

FIG. 4 shows details of the processing contents of step 302. In FIG. 4, one event is fetched from the event queue at step 401, and the event is checked at step 402 to see if the hardware event is a pointer operation. If so, at step 403 the pointer cursor is moved. -Redraw. Next, in step 404, the event is transmitted to the client which should be notified of the occurrence of the hardware event.
In step 405, the presence or absence of an event remaining in the event queue is checked. If there is any event, the process returns to step 401, and if not, the process ends.

Returning to FIG. 3, in step 303, the presence or absence of a request from the client is checked, and if there is, it is processed in step 304.

FIG. 5 shows details of the processing contents of step 304. In step 501, the type of request from the client is first checked, in step 502 a pointer to the processing routine for that request is obtained, and in step 523 that processing is executed. Next, if the positional relationship of the windows such as the overlapping state of the windows and the shape of the windows changes due to the processing of the request performed in the previous step, the 119 image area description table of FIG. 1 is reconstructed. A method of determining whether or not the positional relationship of windows has changed will be described later. The 119 image area description table is constructed corresponding to each window of the X window system.

FIG. 6 shows the basic window management method in the X server. Inside the X server, all windows are managed in a hierarchical structure in which a root window (a window located at the back, which extends over the entire screen) is a parent window at the highest level. Figure 6 shows the positional relationship of the windows on the screen,
The correspondence with the window hierarchical structure managed by the X server is illustrated. Each window has a data structure called a Window structure (see FIG. 6C). Win
As shown in FIG. 6B, the dow structure has pointers (WindowPtr type) to the parent, front and rear siblings, the first child, and the last child of the window structure. Figure 6
(B) shows a state of such an information link between the parent and child and siblings. Further, the Window structure has information of a rectangular list called a clip list, which is a part of the window that does not appear on the screen, such as when another window covers the window.

FIG. 7 shows the internal structure of the 119 image area description table.
Shown in. The 701 image area description table has N entries,
701a, 701b, 701c, 701d, 701e. The value of N depends on the hardware design. The internal structure of each entry is as shown in FIG. 7
Each entry of the 01 image area description table is used to describe one window or one clip area. Each of these is a rectangular area. However, when describing a window, next_clip_ent_in
d is 0. On the contrary, when describing the clip area, p
arent_ent_ind, next_siblin
g_ent_ind, first_child_ent
_Ind, last_chile_ent_ind, f
irst_clip_ent_ind is set to -1, and next_cl is set when the next clip area does not exist.
ip_ent_ind is set to 0.

Returning to FIG. 5, in step 505, the Windows used by the X server for window management as described above.
Reconstruct the 119 image area description table using the w structure. Whether or not reconfiguration is necessary is determined by the type of client request. That is, if the request is any of the following, reconfiguration is performed. -Configure window-Circulate window-Destroy window-Map window-Unmap window-UnmapSub window-Reparent window

In step 506, it is checked from the request processed in step 503 whether or not the image area separation, that is, the window for image processing and the window for approximate color conversion can be identified. Set the value of 801e digitize_method of the corresponding entry in the 199 image area description table. This image area separation is performed according to the type of request. That is, when the request is as follows, it is determined as shown on the right. -Put Image-Image processing-Image Text8-approximate color conversion-Image Text16-approximate color conversion-Poly Text8-approximate color conversion-Poly Text16-approximate color conversion

Returning to FIG. 3, in step 305, the number of clients currently operating is checked. If it is not 0, the process returns to step 301, and if it is 0, the process ends.

So far, the operation of the 201 graphic program for generating the image area information has been described.
Next, the operation of the 120 binarization control circuit will be described.

FIG. 9 shows a flow of operation of the 120 binarization control circuit. In step 901, cur_win_ent_
Set ind to the image description table entry (= 0) in the root window. In step 902, cur_
Performs binarization conversion of the current window specified by win_ent_ind.

FIG. 10 shows details of step 902. In step 1001, a mask for the portion of the current window where the binarized region is formed and a binarized region mask are generated. 801e digitize_m of the current window
With reference to the method, the 114 binarization circuit selection switch is set to the image processing side when it is 1 and to the approximate color conversion side when it is 0. Next, in step 1005, the image data of the binarized area is processed using the binarized area mask.
The data is sequentially transferred from the bpp frame buffer to the palette. At this time, the 120 binarization control circuit also passes the binarized area mask to the 116 image processing logic circuit so that the binarized image processing can be performed correctly.

Returning to FIG. 9, 903-908 indicates 119.
This is a process for binarizing all windows in the image area description table.

(Other Embodiments) In the above embodiment, if the image processing method does not need to read the data in the binarized frame buffer for storing the data after the image processing like the dither method, 117 The binarized frame buffer may be omitted.

As described above, according to the above-described embodiment, the area in which the binary image data obtained by performing the image processing on the image data of the multi-valued frame buffer is to be displayed and the approximate color conversion is performed to obtain the binary image data. Image area information generating means for generating image area information designating an area for displaying the image data to be displayed, image area information storing means for storing the image area information, pixel data in a multi-valued frame buffer, and a palette. Image processing means for performing image processing based on generated color information, and approximate color conversion for converting pixel information in a multi-valued frame buffer and color information generated by a palette into color data that can be displayed on a display. Means, and color information generated by the pixel data and the palette in the multi-valued frame buffer, the image processing means or the approximate color conversion means. Binarization circuit switching means for switching to and from which the image data is transferred from the multivalued frame buffer to the palette based on the image area information stored in the image area information storage means, and the binarization circuit By appropriately switching the switching means and providing a binarization control means for passing necessary information to the image processing means, a display image whose visual display color number is increased by image processing is provided. In the above, the effect of improving the visibility can be obtained by displaying the image data of the portion (see FIG. 11) where the outline is ambiguous and visibility is reduced (see FIG. 11) by performing the approximate color conversion instead of the image processing. can get.

[0027]

As described above, according to the present invention, a high quality display image can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a system of the present invention.

FIG. 2 is a block diagram showing a logical configuration of the present invention.

FIG. 3 is a diagram showing an outline of internal processing of an X server.

FIG. 4 is a diagram showing processing contents.

FIG. 5 is a diagram showing processing contents.

FIG. 6 is a diagram showing a window management method in the X server.

FIG. 7 is a diagram showing an internal structure of an image area description table.

FIG. 8 is a diagram showing an internal structure of an entry.

FIG. 9 is a diagram showing a flow of operations of the binarization control circuit.

FIG. 10 is a diagram showing a flow of operations of the binarization control circuit.

FIG. 11 is a diagram showing a display example.

[Explanation of symbols]

 101 Central processing unit

Claims (4)

[Claims] 1. An area for displaying binary image data obtained by performing image processing on image data of a multi-valued frame buffer and a binary image data obtained by performing approximate color conversion on a screen. A display control device comprising: an image area information generating means for generating image area information designating an area based on software of a computer; and a processing means for processing the image data based on the image area information. 2. The display control device according to claim 1, wherein an algorithm used by the image processing means is a dither method. 3. The display control device according to claim 1, wherein the algorithm used by the image processing means is an error diffusion method. 4. The average density preserving method is used as an algorithm used by the image processing means.
The display control device described in 1.