JPS61132995A - Electronic color signal generator - 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 The present invention comprises a memory having addressable memory locations for storing color reference data and a signal input connected to an address input terminal of the memory for receiving a digital signal representing a pixel to be displayed. an address generator having a terminal for selectively addressing a memory location by generating an address word including a first address portion determined by a received digital signal; and a selected memory connected to the data output terminal of the memory; and a readout device for reading out color reference data from a location.

Such an electronic color signal generator is covered by British patent CB203274.
It is known from the specification OA. The color reference data stored in memory identifies different colors that differ in hue, saturation, and intensity. The meanings of these three terms used in this prior patent specification and used herein are as defined in standard dictionaries. Therefore, "hue" is an attribute of a color that distinguishes a color as red, green, blue, or an intermediate color between these colors, and has a correlation with the dominant wavelength of the color. "Saturation" refers to the purity of a color, ie, the degree to which the color is mixed with white light.

"Intensity" refers to the brightness of a color.The color reference data for any particular color is the red, green, and green that when mixed will yield a particular color of appropriate hue, saturation, and intensity on the display device of a color image display system. It consists of three parts, each related to the mixing ratio of the three primary colors: and blue.When a pixel is to be displayed in a particular color, a digital signal representing the color of this pixel is fed to an address generator.Address A generator is responsive to the received digital signal to generate an address that selects a memory location within said memory in which color reference data for said particular color is stored; Color reference data is read by a readout device and supplied to a display device so that a particular pixel is displayed in a particular color.

A disadvantage of known electronic color signal generators is that the same color reference data must be used for the same color of different intensities, or the memory must be reprogrammed, which makes it difficult to operate the system. This is a roundabout way to do so. However, the color properties of hue, saturation, and intensity are not simple functions of the mixing proportions of red, green, and blue (they are highly interdependent and interrelated by complex mathematical formulas, and their relationships are This is further complicated by the non-linear response or "gamma" of the cathode ray tube, which means that the intensity of many colors depends on the hue of these colors due to linear changes in the proportions of the red, green, and blue mixture that produce these colors. It has been established that it is unlikely to be possible to change the saturation without changing the saturation.

This inability to independently vary the intensity of a color without affecting its hue and saturation is problematic when displaying images on the screen of a display device. For example, when increasing the intensity of a colored portion of a displayed image to emphasize that portion, undesirable changes in the hue and/or saturation of that portion may occur. Further, when the intensity of a colored portion of a displayed image is lowered to generate a subtitle display window, for example, an undesirable change in the hue and/or saturation of that portion may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electronic color signal generator that allows the intensity of a displayed color to be varied without affecting the hue and saturation of that color and without having to reprogram the memory. be.

The present invention provides a color signal generator of the type mentioned above, comprising:
The address generator includes an intensity signal input terminal for receiving an intensity value indicative of the display intensity of the pixel, and generates a separate second address portion for each received intensity value to identify the first and second address portions for each pixel. an address word comprising two address portions, and said memory comprises a plurality (N22) of memory sections, each section being allocated for storage of a respective separate color reference data; and a second address portion, and a memory location within the selected memory section is selectable by the other address portion.

By dividing the memory into multiple memory partitions, each partition containing separate color reference data, the color reference data for each color in the standard range is stored in one partition of memory, and the color reference data for each color in the standard range is stored in one partition of the memory. Color reference data for high and/or low intensity versions of the color reference data may be stored in other sections of memory. Therefore, it is no longer necessary to reprogram the memory to obtain another set of color reference data. Further, when an intensity value is received at the intensity signal input terminal, an address generator generates a specific second address portion for the intensity value. At this time, the address word for the pixel is a combination of the first address part and the second address part. This creates a specific address word that addresses specific color reference data for a specific combination of color and intensity. In this case, the first and second
One of the address portions selects a memory section and the other address portion selects particular color data within the selected memory section. This specific color reference data displays the associated pixel in the desired combination of color and intensity without affecting hue and saturation.

According to this means, the nonlinearity and hue of the color cathode ray tube,
Human perception of color as well as the complex relationship between color characteristics of saturation and intensity can be taken into account.

Incidentally, US Pat. No. 4,183,046 discloses that the color intensity of the pixel of the image to display the word of the first digital signal,
A color signal generator is disclosed that separates the data into three groups of data bits that define hue and saturation. The generator uses data bits corresponding to hue and saturation to address a memory containing color reference data representing only hue and saturation magnitudes. This data is read out as a second digital signal and converted by a digital-to-analog converter into an analog signal that acts as a red, green and blue video signal driving a three-electron gun color cathode ray tube to reproduce the first digital signal on its screen. form an image represented by . Data bits corresponding to the intensities are applied to a digital-to-analog modulator to modulate the magnitude of the red, green, and blue video signals. This allows intensity to be changed without changing hue and/or saturation.

In a preferred embodiment of a color image display device comprising a color signal generator according to the invention, each of said memory sections has a small number (
each having a predetermined number of memory locations, each allocated for the storage of color reference data of different colors belonging to a particular intensity value, these memory sections being selectable by said second address portion and the selected memory; A memory location within the partition is made selectable by the first address portion.

The predetermined number of memory locations in each memory section is given by the minimum number of colors available in the color image display system. Particular embodiments allocate one memory partition per intensity level. In this case, a simple implementation of memory partitioning as well as partition selection is obtained.

In a second preferred embodiment of a color image display device comprising a color signal generator according to the invention, each of said memory sections has at least a predetermined number of memory locations, each of which has different intensities belonging to a particular color. memory sections allocated for storage of color reference data, making these memory sections selectable by said first address section and memory locations within the selected memory section selectable by said second address section. This particular embodiment allocates one memory section for each color available in the system. Also in this case,
A simple implementation of memory partitioning as well as partition selection is obtained.

The invention will be explained with reference to the drawings.

The image display system shown in FIG. 1 includes a color signal generator consisting of a color memory 1, a memory address circuit 2, a memory read circuit 3, and a selection circuit 11. This image display system consists of three digital-to-analog converters 4,
5 and 6, a color cathode ray tube display 7, a processor 8, a human power device 9, a display memory 10, and a timing circuit 12.

In operation of the color signal generator, data representative of the image to be displayed is received from the input device 9 and, under the control of the processor 8, is supplied to the display memory 10 and stored therein. The input device may be, for example, an electronic writing tablet or other graphic display that produces a static color image on the screen of the display device 7. The generated image is in the form of a bitmap, for example 512
It may consist of a matrix of X512 pixels. The color of each pixel of the displayed image is stored as a multi-bit word in display memory 10, which is a random access memory. For convenience of explanation, each pixel is assumed to be capable of displaying one of 16 types of arbitrary colors.
Let each word be represented by a separate 4-bit word in zero.

The display device 7 receives line and field synchronization signals LS and F.
Controlled by S (interlaced or non-interlaced), rask scanning is performed to generate the image display. In synchronization with the rask scan, a 4-bit word is read from display memory 10 which defines the color of the pixels of the image to be displayed. The four bits of each word are read out in series on lead line 13 and supplied to memory address circuit 2 as a first digital signal IDS. Circuit 2 latches 4 bits of each received word and converts these 4 bits into 5 bits.
It is supplied in parallel to the first four lead wires a1 to a4 of the lead wire group of memory address lead wires a1 to a5 of the book. The remaining address lead a5 receives a logic rr_Ou or '1'' from the selection circuit 11, as described below.

Color memory 1 is a read-only memory or random access memory, and includes a color look-up table (CLOT).
). Color memory 1 is the first memory section with 16 memory locations! , )1, and those 16 memory locations have bits on address lead a5 having the value “0”.
``'', selective addressing can be performed by a combination of 0'' and ``1'' in the 4-bit word of address leads a1 to a4. The color memory 1 further has a second section M2 comprising 16 memory locations, the 16 memory locations having bits on the address lead a5 having the value "1".
'', selective addressing can be performed by a combination of the 4-bit word IIOII of address read mat-a4 and "1''.

It is assumed that each memory location in each partition has the capacity to store 12 bits representing color reference data. In this case, 16 different 12-bit words can be selected and stored in each memory partition out of a total of 4096 (=4K) possible 12-bit words. When a memory location is addressed, the bits of the 12-bit word stored there are serially read out on lead 14 as a second digital signal 2O3 and latched into memory read circuit 3.

The 12 bits of the latched word are then divided into three groups of 4 bits each and connected to three address lead groups aR, aG.
and aB to digital-to-analog converters 4.5 and 6, respectively. These converters receive 4
The bit groups are converted into red, green, and blue video signals, respectively, and supplied to leads R, G, and B to drive the color cathode ray tube display device 7.

It is assumed that the color reference data stored in the 16 memory locations of memory section M1 represents a standard range of 16 colors. These memory locations can be addressed with 4-bit words on address leads a1-a4 as described above. In the present invention, it is assumed that the color reference data stored in the 16 memory locations of memory partition M2 represent different intensities (eg, low intensities) of the 16 colors that make up the standard range of colors. Each 4-bit word on leads a1-a4 can also address memory locations in memory IJM2 containing different intensities of the standard intensity colors contained in the memory locations addressed in memory section M1. Under the control of processor 8, selection circuit 11 selects address lead a5.
generates a 0" or 'l" bit to select the memory location within memory section M1 or memory section M2 addressed by the 4-bit word on address leads a1-a4. Color reference data is then read from the selected memory location to produce a standard intensity color or a different intensity version thereof for the relevant pixel of the displayed image.

The selection of a color of standard intensity or a color of different intensity can be realized on the basis of an operator's request by providing a selection signal at the input device 9 or on the basis of the requirements of an executing program. The processor 8 converts the coordinates of the display area into the display intensity of the pixel (
together with an intensity value indicating the standard intensity or a different intensity) to the selection circuit IL. This selection circuit also receives a clock signal from the timing control circuit 12 and is scanned along with the display image to determine when the color memory is addressed for display of said display area, depending on the received intensity value on the address lead. Supply a "0" bit or 'l' bit to a5.

The image displayed on the display device 7 can be divided into, for example, 16 rectangular display areas and these areas can be numbered from 0 to 15. In this case, the processor 8 supplies the display area number (4 bits) and the associated intensity indication signal (1 bit) to the selection circuit.

Another example of a selection circuit uses addressable memory loaded by processor 8.

In setting up this color signal generator, processor 8 is used in conjunction with an interactive software program to visually edit the color reference data in color memory 1. Using this program, the user first sets and stores the bit values of three 4-bit groups for each color in the standard range into memory locations in memory partition MI. Following this process, the different intensities of each color are set subjectively by the user by changing the bit values of the three 4-bit groups for that color until a satisfactory result is obtained. The four bit groups of modified bit values for each color are then stored in memory locations within memory partition M2. This subjective determination of colors of different intensities changes the perceptual characteristics of the human eye from the nonlinearity or "gamma" of color cathode ray tubes and the complex relationship between the color characteristics of hue, saturation, and intensity. can be considered together.

The timing of the operation of the color signal generator is controlled by a timing control circuit 12. As mentioned above, this timing control circuit 12 reads data from both memories 1 and 10 serially. However, it is of course possible to read data from these memories in parallel by appropriately modifying the timing control circuit.

The color memory 1 may have a plurality of sections (N≧2). For example, three memory partitions may be provided, with an additional memory partition storing color reference data for high intensity versions of a standard range of colors. When three memory sections are provided in the color memory 1, it is necessary to add one address lead line such as lead line a5 to supply the 2-bit selection code from the selection circuit 11.

In the variant shown in FIG. 2, the color memory 1 comprises three sections Ma, Mb and MC;
Address lead lines a1 to a4 are connected in common. Each of these separate sections has 16 memory locations, and each corresponding memory location of each section stores color reference data for each of the 16 standard, high, and low intensity colors, respectively. Thus, when a 4-bit word is applied from address circuit 2 to address leads a1-a4, three memory locations containing color reference data for the associated color are addressed simultaneously. In this example, the selection circuit 11 has separate selection leads 51 to S3 connected to the separate sections Ma, Mb, and Mc, respectively. When one of these selection leads is energized by the selection circuit 11, the associated memory section is activated so that only color reference data from the selected memory location of that memory section can be read. The read color reference data passes through the OR gate 15 and is latched into the readout circuit 3 as in the previous example.

In the above example, each memory section contains gold reference data of a particular intensity. It is also possible to partition the memory 1 into other forms, for example by assigning a specific color to each memory partition. In this case, each partition's memory location stores color reference data of various intensities for that particular color. In this example, the first part of the address word consisting of bits a1-a4 selects the memory partition, and the second part (a5 or S
1-S3) will select a memory location within the selected memory partition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color signal generator according to the present invention, and FIG. 2 is a block diagram of a modification of the color signal generator shown in FIG. 1... Color memory 2... Memory address circuit 3... Memory read circuit 4.5.6... Digital-analog converter 7...
Color cathode ray tube display device 8...processor 9...input device 10...
・Display memory 11...Selection circuit 12...Timing control circuit IO3...First digital signal M11M2; Ma9Mb1MC...Memory section a1~
a4...first address portion a5. St, S2. S3--Second address part 24] S...Second digital signal (color reference data) R
, G, B...Red, green, blue video signal patent applicant
N.B.Philips Fluiran Benfabriken 11 I 1

Claims (1)

[Scope of Claims] 1. A memory having addressable memory locations for storing color reference data, and a signal input terminal connected to an address input terminal of the memory and receiving a digital signal representing a pixel to be displayed. an address generator for selectively addressing a memory location by generating an address word including a first address portion determined by the received digital signal; an electronic color signal generator for a color image display system, the address generator comprising an intensity signal input terminal for receiving an intensity value indicative of a display intensity of a pixel; A separate second address part is generated for each pixel to form an address word including a first and a second address part for each pixel, and the memory comprises a plurality of (N≧2)
memory partitions, each partition being allocated for storage of a respective separate color reference data, making the memory partitions selectable by one of said first and second address portions, and providing a memory location within said memory partition. An electronic color signal generator characterized in that the color signal can be selected by the address part of the other. 2. A color image display device comprising an electronic color signal generator according to claim 1 and connecting the reading device to a color display device, wherein each of the memory sections has at least a predetermined number of memory locations. and having a memory section allocated for the storage of color reference data of different colors, each belonging to a particular intensity value, making these memory sections selectable by said second address part and specifying a memory location within the selected memory section. A color image display device characterized in that the first address portion is selectable. 3. A color image display device comprising an electronic color signal generator as claimed in claim 1 and in which the reading device is connected to a color display device, wherein each of the memory sections has at least a predetermined number of memory locations. , each of which is allocated for the storage of color reference data of different intensities belonging to a particular color, these memory sections being selectable by said first address portion and a memory location within said memory section being selected by said first address portion; A color image display device characterized in that selection is made possible by a second address part.