JPH05249939A - Color pallet circuit for converting digital information into analog information to prepare color pixel - Google Patents

Abstract

PURPOSE: To increase the number of colors able to be displayed by a color pallet without proportionally increasing the size of a required memory. CONSTITUTION: The color pallet circuit 16 is provided with 1st and 2nd color lookup tables 18, 19 the addresses of storing positions in the lookup tables 18, 19 are specified by information read out from a video bit map, the contents of information stored in selected storing positions are combined by a digital adder or a digital multiplier, the combined signal is converted into an analog signal, which is used for generating a color pixel. The use of the combining means allows the generation of colors to be displayed of which number is larger than the sums of the numbers of storing positions in the lookup tables 18, 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION

[0002]

FIELD OF THE INVENTION The present invention relates to the field of digital electronics related to the generation of color displays, and more particularly to color palette circuits utilized in the generation of drive signals for generating color displays.

[0003]

2. Description of the Prior Art FIG. 1 shows a typical prior art attempt at a color palette circuit 1 in the form of a highly simplified and block diagram. A typical current CMOS color palette circuit is implemented on an integrated circuit chip and the block designated by reference numeral 2 marks the boundary of the integrated circuit, ie, circuits within boundary 2 are found on the chip and they Indicates that the inputs and outputs are external. The color palette circuit 1 includes a color look-up table 3, which is typically 24 bits wide each.
A RAM device having 56 memory locations, each memory location in the color look-up table 3 being loaded with digital information from an external source, defining a combination of red, green and blue components and providing 256 unique colors. Make up. The 256 addresses contained in the color look-up table 3 are accessed by the information received from the video bitmap, which is via the bus 4 with eight individual lines, which in this figure is / is via the bus and It is indicated by the numeral 8 adjacent to /. With an 8-bit address input, each one of the storage locations can of course be uniquely addressed. In FIG. 1, as throughout the application, parallel buses are indicated by lines with / through them and the number of individual lines in a parallel bus is indicated by the number adjacent to /. The color palette circuit 1 further includes a red digital-analog converter 5, a green digital-analog converter 6 and a blue digital-analog converter 7. The terms digital-to-analog converter and the acronym "DAC" are used herein to refer to digital voltage converters or digital current converters. When a memory location in the color look-up table 3 is addressed, the information contained in the storage location is provided to the red digital-to-analog converter 5 via bus 8 in 8 bits each, and the 8 bits of green information are provided in bus 9 Via the bus to the green digital-to-analog converter 6 and likewise the 8-bit blue information is provided via the bus 10 to the blue to digital-analog converter 7. The digital information received by each of the digital-to-analog converters is converted into an analog signal to provide red, green and blue components, which are provided at outputs 11, 12 and 13 respectively for use in generating color pixels. In some applications it is desirable to be able to provide 256 or more unique colors and a typical prior art attempt to do so is to provide a larger look-up table with additional storage locations. .. For example, to provide 4096 displayable colors, it is necessary to utilize 12 bits of address information to address 4096 storage locations. It will, of course, be appreciated that a substantially larger color look-up table is required to accommodate this significantly increased number of memory locations, which correspondingly utilizes a substantially larger area on the integrated circuit chip. However, it may be infeasible in terms of other circuitry required to be included on the chip.

A typical commercial prior art color palette circuit is described in Advanced Micro Devices, Inc., 901 Thompson Place, (Th.
ompson Place) P. O. Box 3453, Sunnyvale, California, (Sunnyvale, Californi
a) Available from 94088, which is Am81C
It is called 471/478. This color palette is 256X
18 (24) color look-up table and 15X18
(24) Overlay registers can be used and 271 colors can be displayed. In this device, the output from either a color look-up table or an overlay register (which may be considered another look-up table) is applied to a digital-to-analog converter to generate the red, green and blue drive signals. The circuit, however, does not have the ability to combine the information from the color look-up table with the information from the overlay register and use the resulting combined information to generate an analog drive signal. It would be desirable to be able to provide a significantly increased number of displayable colors without a corresponding substantial increase in the amount of memory required for the color look-up table.

[0005]

SUMMARY OF THE INVENTION It is an object of this invention to increase the number of colors that can be displayed by a color palette circuit without a proportional increase in the amount of memory required.

In accordance with the present invention, the foregoing object can be achieved as follows, which utilizes first and second color look-up tables to provide separate address inputs to the first and second color look-up tables. And combining means for combining the outputs of the first and second look-up tables with the resulting output of the combining means provided to the plurality of digital-to-analog converter circuits to provide an analog output. And the combination can be utilized by external circuitry to generate color pixels.

According to another feature of the invention for achieving the above object, a color palette circuit capable of generating more displayable colors than the number of storage locations utilizes color bitmaps. Given by addressing a position in the color look-up table, its output is provided to the combining means and further a second input is provided from the saturation bitmap to the combining means, the output of the combining means being a digital-to-analog converter circuit. And provide an analog drive signal to produce the color pixels.

In accordance with another embodiment of the present invention, a color palette circuit is provided which utilizes a first input from a color bitmap to address the location of a color look-up table and a plurality of combinations. Utilizing a second input from the intensity bitmap that feeds the circuit produces an increased number of displayable colors without increasing memory storage locations. Each of the combinational circuits includes a second input for receiving information from the color look-up table and the combined result of the information from the luminance and color bitmaps is combined by combining means before the digital-to-analog converter. The circuit converts it to an analog circuit.

According to yet another embodiment of the present invention, as a variation of the previous color palette circuit, a luma lookup table is prepared to receive information from the luma bitmap and the luma lookup table outputs are combined. Provided to the means, thus achieving a significantly increased number of displayable colors without a corresponding large increase in the number of storage locations required.

According to yet another feature of the invention,
The above-described embodiments of the present invention may be implemented by further utilizing a gamma-correction look-up table between the combinational circuit and the digital-to-analog conversion circuit, these modifications compensating for the non-linearity of display luminosity. Adjustments are thus provided, which may be, for example, a cathode ray tube monitor as a function of analog current input to the display or drive voltage.

Other objects and advantages of the present invention will become apparent from a review of the specification and drawings.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the invention is shown in FIG. As shown in FIG. 2, the color palette circuit 16 receives color information from the video bitmap not shown via bus 17, which is the digit 1 adjacent to /.
Included twelve lines to provide the color palette circuit 16 with 12 bits of information, indicated by 2. Color palette circuit 1
6 includes a first color look-up table indicated by reference numeral 18 and shown in block diagram form as color look-up table "A". The color look-up table 18 includes 256 storage locations, each of which has the ability to store 24 bits of information. Color palette circuit 1
6 also includes a second color look-up table, indicated by reference numeral 19 and referred to in the block as color look-up table "B". The color lookup table 19 contains 16 storage locations, each of which has the ability to store 24 bits of information. Color look-up tables 18 and 19 may preferably be RAM solid state memory devices of the type utilized in the prior art. The information loaded into these color lookup tables is provided from an external source (not shown) and loading is done in the same manner as utilized in the prior art. To address the color lookup table 18,
Eight of the twelve bits from bus 17 are provided to the address inputs of color look-up table 18. The remaining four of the twelve lines on bus 17 are coupled to the address inputs of color look-up table 19 for selecting addresses in color look-up table 19. The outputs from color look-up table 18 and color look-up table 19 are combined by combinational circuit means, which may be, for example, digital summing circuits or digital multiplying circuits. In the embodiment shown in FIG. 2, a digital adder 20 is provided to combine the red component outputs from the color look-up table 18 and the color look-up table 19 and a digital adder 21 of the color to be displayed. Used to add the resulting output from the memory location addressed in color look-up table 18 and the memory location addressed in color look-up table 19 to produce the green color component, and also digitally. Adder circuit 22 combines the outputs from color look-up table 18 and color look-up table 19 to generate a digital signal indicative of the blue component of the color of the pixel to be displayed. The sum of the digital information received by the digital adder 20 is provided via its bus 23 at its output to a digital-to-analog converter 24, which converts the digital information received via the bus 23 into an analog signal, which Two
Available in 5. Similarly, the output from digital adder 21 is provided to digital-to-analog converter 26 via bus 27 and an analog signal having a magnitude indicative of the digital signal received via bus 27 is provided at output terminal 28. .. In a similar manner, the digital adder 2
The resulting digital sum of the addressed look-up portion of the color look-up table 18 and the color look-up table 19 prepared to 2 produces a digital sum, which via the bus 29, the digital adder 2
2 is given to the digital-analog converter 30 at the output,
It converts the received digital signal into an analog value representing digital information and provides this analog signal at terminal 31. The output from each of the adder circuits (20, 21 and 22) is truncated by 1 bit.

The color palette circuit 16 includes a digital adder 20, 21 and 22 together with a color look-up table 1.
8 and color look-up table 19 are utilized to allow the display of 4096 unique colors achieved by inputting 12 bits of information from the video bitmap. However, compared to the prior art, the color palette circuit 16 requires memory means having a total of 272 addressable storage locations, whereas in the prior art utilizing a single memory means 4096 unique. 4096 storage locations in the memory means would be required to generate the displayable colors. Thus, by utilizing a plurality of memory means to store color information, the overall storage location required is significantly reduced, thereby providing the space required on an integrated circuit device, for example a color palette circuit. To be done.

FIG. 3 shows a simplified example for a circuit of the type shown in FIG. In this simplified example, the color palette circuit 36 will provide 2 ^{a + b} number of unique colors on the output line 37 from the combining means 38 when the combining means 38 is a multiplier. A first memory, referred to as memory A and designated by reference numeral 39, contains 2 ^a storage locations for storing digital information loaded into it from a source not shown. A second memory, designated by reference numeral 40, memory B, contains 2 ^b storage locations for storing digital information. Memory A is bus 4
An address input is received via 1 and the bus contains "a" number of lines of address information to uniquely identify one of the ^2a storage locations. In response to receiving the address signal, the memory A provides the information stored in the selected storage location via line 42 to the combining means 38. Similarly, memory B contains 2 ^b storage locations and receives address information via bus 43, which bus contains “b” number of lines and stores any one of the 2 ^b storage locations in memory B. Uniquely identify. The information contained in the selected storage location in memory B is provided at the output of memory B and transferred via line 44 to the input of the combining means 38. The identity of the storage locations in memory A and memory B to be addressed is provided via a parallel bus, bus 45, with individual lines equal in number to a + b. Although the digital address information is provided from the single bus 45 subdivided into buses 41 and 43 in the example of FIG. 3, it is, of course, recognized that separate, uncombined input buses may provide the address information. Will. In the prior art, a single memory means having ^{2a + b} storage locations was required to display ^{2a + b} individual colors.

In the prior art, the determination of a color pixel to be generated by addressing a storage location within a color look-up table 3, for example as shown in FIG. 1, was made from a predefined video bitmap. .. In a first embodiment of Applicant's invention, FIG.
By distributing the number of bus inputs between the memory means 18 and the memory means 19, as shown in
And by combining the outputs using combining means and then by converting the digital result to an analog value, the number of colors that can be displayed is increased without an equal increase in the number of memory locations.

An alternative embodiment for providing an increased number of displayable colors without increasing the required storage element size is an alternative embodiment of Applicant's invention shown in FIG. Shown as an example. The color palette circuit 49 receives a color bitmap (not shown) via a bus 50 containing eight lines.
Receives color information from. The second input to the color palette circuit 49 comes from a saturation bitmap (again not shown) via a bus 51 having four lines. For a pixel to be displayed, the first piece of information that determines the color of the pixel to be displayed is the color lookup table 52.
Identified by addressing one of the 256 storage locations at, which is, for example, a RAM memory, and which in this particular embodiment contains 24 bits of information at each of the 256 storage locations. It will, of course, be appreciated that the number of bits of information that can be stored in any memory location as well as the number of memory locations provided in the memory means can be varied to suit the needs of a particular system. Color lookup table 52 of 25
The information stored in the six storage locations is loaded from an external source, not shown, and together with the information received from the saturation bitmap, the predetermined information at the storage location determines the color that will be displayed. 8 for each selected storage location in the color lookup table 52
Bits of red, 8 bits of green and 8 bits of blue information are provided, the red information is provided via bus 53 to a first input to a red adder 54 for the eight green components of the color. Additional bits of information are provided via bus 55 to one of the inputs of green adder 56 from the selected storage location in color look-up table 52. Similarly, the 8-bit information indicating the blue component of the color to be displayed is on the bus 57.
To one input of the blue adder 58 via. The second inputs of red adder 54, green adder 56, and blue adder 58 are each informed via bus 51 to define the saturation level, which is the summation previously shown in this particular embodiment. The same is true for each of the instrument circuits. Further, the combinational circuits (54, 56 and 58) may be selectively programmable from an external source so that the digital operations they perform can be modified under program control.
Returning to the specific embodiment of the color palette circuit 49, the bus 53
And the result of the digital addition of the information received by the red adder 54 via bus 51 is provided to the DAC digital-to-analog converter 60 via bus 59 having eight lines, which is received via bus 59. The digital information is converted into an analog signal provided at the output terminal 61. The least significant bit resulting from the addition of red adder 54 is truncated. The resulting digital signal provided at the output of green adder 56 is provided to digital-to-analog converter 63 by bus 62 having 8 bits, which provides the digital information received on bus 62 at output 64. Convert to signal.
The least significant bit of the sum generated by the green adder 56 is truncated so that only the 8-bit output is provided by the green adder 56. Similarly, the result of the digital addition of blue adder 58 is provided via bus 65 to a digital-to-analog converter 66 which converts the digital information into an analog signal which is provided at output 67.
Truncate the least significant bit from the blue adder 58 is the blue adder 5
It is done to give an output of 8 to 8 bits.

With the configuration of color palette circuit 49, the maximum number of uniquely identified color pixels that can be generated using this circuit will be equal to 4096. Color palette circuit 49
Alternative embodiment of increasing the number of bits of information provided by the saturation bitmap, color lookup table 5
2 includes increasing the number of bits contained in each of the memory locations and / or increasing the number of memory locations in the color lookup table 52. Yet another alternative embodiment of the color palette circuit 49 is a combination means (red adder 54,
With the inclusion of a gamma correction look-up table between each of the green adders 56 and blue adders 58) and their respective correlated digital-to-analog converters. The use of gamma correction look-up tables is also described in connection with the seventh, eighth and ninth embodiments of this invention. As explained before and after, a more accurate color display is achieved when the brightness of the display device used with the color palette circuit is non-linear with respect to a given drive voltage or drive current, then the gamma correction. Is used.

A third embodiment of the invention is shown in FIG. In the third embodiment, the color palette circuit 70 utilizes a first input from a color bitmap (not shown) and a second input from a luminance bitmap (not shown again) to be displayed. Specifies the color. Color palette circuit 7
0 uses the color lookup table 71, which is 64
Addressable storage locations, each of which is 24
It is possible to store bits of information. The features for each color to be defined by its location in the color look-up table 71 are loaded into the color look-up table 71 from an external source not shown. The information from the color bitmap is used to select a predetermined storage location in the color look-up table 71 via the bus 72, which bus has six lines and the address of the color look-up table 71. Connected to input. When selecting an address in the color lookup table 71, 2
The information in eight of the four positions is transmitted via bus 73 to a digital multiplier 74, which multiplies the digital information with the digital information received from the luminance bitmap via bus 75 to produce a digital product. Present, which is provided via bus 76 to a digital-to-analog converter 77, which converts the received digital information into an analog signal, which is provided at terminal 78. The resulting analog signal at terminal 78 is used in generating the red component of the color pixel to be displayed. In a similar manner, another 8 bits from the addressed storage location in color look-up table 71 is provided to digital multiplier 80 via bus 79. At the same time as presenting the 8-bit information from the color look-up table 71 to the digital multiplier 80, the second input to the digital multiplier 80 via bus 75 is multiplied by the digital information received via bus 79. It then produces a digital product at its output, which is applied via bus 81 to a digital-to-analog converter 82, which converts the received digital information into an analog signal, which is applied at terminal 83. Eight bits of information are provided from the addressed location in color look-up table 71 to digital multiplier 84 via bus 85 to generate the blue component of the color pixel. The product of the information received by digital multiplier 84 from bus 85 and bus 75 is bus 86.
To a digital-to-analog converter 87, which converts the digital information into an analog signal, which is provided at terminal 88. 6 bits x 8 bits multiplication is 14
It will be appreciated that it produces a product with bits. In the color palette circuit 70, the red multiplier 74,
The outputs of green multiplier 80 and blue multiplier 84 are truncated to 8 bits by dropping the 6 least significant bits. By utilizing the color palette circuit 70, the maximum number of unique displayable colors is 4096. Modifications to the color palette circuit 70 may include increasing the number of storage locations in the color look-up table and increasing the bits of information provided from the intensity bitmap. The embodiment of the invention shown in FIG. 5 is particularly desirable because the data in each bitmap can be conveniently organized to display chromaticity and luminance information.

A fourth embodiment of the invention is shown in FIG. The color palette circuit 91 utilizes inputs from the color and luminance bitmaps. Many circuit elements in FIG. 6 are the same as those utilized in FIG. 5, as will be appreciated by comparing FIGS. More specifically, the commonality is color look-up table 71, digital multipliers 74, 80 and 8
4 and digital-to-analog converters 77, 82 and 87. In addition to the circuit in FIG. 5, the color palette circuit 91 has a luminance look-up table, which is designated by the reference numeral 92, has 64 addressable storage locations, each of which stores 6 bits of information. It is possible to The information stored in the luminance look-up table 92 is loaded from an external source (not shown) using conventional circuitry (not shown again). Information from the intensity bitmap is provided via bus 75 to the address inputs of the intensity lookup table 92. The information stored at the selected storage location in the luminance look-up table 92 is provided by bus 93 to the inputs on digital multiplier circuits 74, 80 and 84. The color palette circuit 91 is particularly advantageous because the luminance look-up table allows transformations on the luminance information. A fifth embodiment of the invention is shown in FIG. 7, where the color palette circuit 97 is shown. In this example, the color to be displayed is determined by a combination of information from a color bitmap (not shown) and a luminance bitmap (not shown). Color palette circuit 97 includes a color look-up table 98, which may be in the form of any of the memory elements, which preferably includes 64 addressable storage locations for this embodiment, each of which is 24. It is possible to store bits of information. Information about the displayable colors is loaded into the color look-up table 98 by conventional means and using conventional circuitry. To address a storage location in the color look-up table 98, a bus 99 having six individual lines for providing address information is connected to the address input of the color look-up table 98. In this embodiment, a multiplying digital-to-analog converter circuit is utilized to combine the information received from the color look-up table 98 with the information received from the luminance bitmap.
More specifically, the multiplication digital-analog converter circuit 1
00 transforms the information received and provides at the output 101 an analog signal indicating the drive to be prepared for the red component of the color pixel to be displayed. Similarly, the multiplying digital-analog circuit 102 converts the received information into an analog signal and provides the green driving signal with the information at the output terminal 103.
The blue component of the pixel to be displayed is generated by a multiplying digital-to-analog converter circuit 104 which produces an analog signal at output 105 based on the received input. When a storage location in the color look-up table 98 is addressed, 8 bits of information are provided via bus 106 to the digital input of the multiplying digital to analog converter circuit 100. The information in the additional eight cells in the addressed storage location is provided to the digital input of the multiplying digital-to-analog converter circuit 102 via bus 107 and in another eight storage locations in the addressed storage location. The information in the cells is provided to the multiplying digital-to-analog converter circuit 104 via bus 108. The information provided via buses 106-108 is utilized to provide a first portion of the information which is output 101, 103 to generate color pixels.
And will be used to ultimately generate an analog signal on 105. The second source of signal components utilized in generating the color pixels to be displayed is the intensity bitmap. This second signal component is the bus 109
Generated by converting the digital information received from the luminance bitmap via and provided to the input of the digital-to-analog converter circuit 110. The analog signal generated by the digital-to-analog converter circuit 110, which is a non-multiplying digital-to-analog converter circuit, is transmitted by line 111 to the multiplying digital-to-analog converter circuit 10.
0 to the multiplying digital-to-analog converter circuit 102 by line 112 and to the multiplying digital-to-analog converter circuit 104 by line 113. Color look-up table 98 and digital-to-analog converter circuit 110.
In response to receiving an input from, these combined signals generate an analog drive signal at the output terminal 101 for the red component, 103 for the green component, and 105 for the blue component. To do. The color palette circuit 97 is particularly advantageous because it can be implemented with a cheap multiplying digital-to-analog converter.

A sixth embodiment of the invention is shown in FIG. As will be appreciated by comparing the color palette circuit 97 (in FIG. 7) and the color palette circuit 115 in FIG. 8, the certain circuit elements utilized are the same, and thus the same reference in both circuits. Indicated by a symbol. A luminance look-up table 116 is provided to allow transformations in the luminance information. Luminance look-up table 116 may take the form of any conventional, well-known memory means, and in this embodiment includes 64 storage locations, each of which may store 6 bits of information. The information to be stored in the 64 storage locations of the luminance look-up table 116 is loaded by the user and by conventional means from an external source not shown. Luminance information received from the luma bitmap is provided to address inputs of luma lookup table 116 via bus 109. When a storage location in the luminance look-up table 116 is addressed, the information contained in that storage location is provided to the digital-to-analog converter circuit 110 via bus 117, which is a non-multiplying digital-to-analog converter circuit. The analog signal produced at the output of digital-to-analog converter circuit 110 is coupled to multiplying digital-to-analog converter circuit 100 by line 111. The same signal is also coupled by line 112 to the multiplying digital-to-analog converter circuit 102 and also by line 113 to the multiplying-to-analog converter circuit 104. Color palette circuit 115 is advantageous over, for example, color palette circuit 97 shown in FIG. 7, where it allows for variations in luminance information. In the color palette circuit 97 and the color palette circuit 115, an output generation circuit, and more specifically, a multiplication digital-analog converter circuit 10
0, 102 and 104 utilize the multiplication of the converted analog signals to generate the output voltage at their respective output terminals. Instead of multiplying the generated analog signal,
It will, of course, be appreciated that these output generating circuits can analogically combine the received input signals, for example by adding them together.

The seventh embodiment of the invention is shown in FIG. 9 and includes a color palette circuit 121. Color palette circuit 12
1, a number of circuit elements are color palette circuits 7
0 (shown in FIG. 5), and thus similar circuit components are designated by the same reference symbols used in FIG. In either situation, it is desirable to provide gamma correction in the color palette circuit to compensate for non-linearities in display brightness. In the color palette circuit 121, gamma correction is accomplished by including a gamma correction look-up table, one for each color component, such as a red gamma correction look-up table 122, a green gamma correction look-up table. 123 and a blue gamma correction lookup table 124. In this embodiment, each of the gamma correction look-up tables includes 256 individually addressable storage locations, each storage location being 8 bits wide. These gamma correction look-up tables may be implemented using any suitable memory means, such as solid state memory. The information to be used to achieve the gamma correction is loaded from an external source at the user's request by conventional means not shown. In operation, the input from the color bitmap and the input from the luminance bitmap produce outputs from each of the digital multiplier circuits 74, 80 and 84. A truncation of the 6 least significant bits of the product produced by the multipliers 74, 80 and 84 is performed, thereby providing only 8 outputs from these multipliers. Bus 76 couples the output of multiplier circuit 74 to the address input of red gamma correction look-up table 122 to define one of 256 memory locations in red gamma correction look-up table 122 and at the selected memory location. Information is bus 1
25 to the input of the digital-to-analog converter 77, which receives the received digital signal at the output terminal 7.
Convert to analog signal at 8. The output from the digital multiplier 80 is provided via bus 81 to the address input of the green gamma correction lookup table 123 and the information at the selected storage location is output from the output of the green gamma correction lookup table 123 via bus 126. Applied to the input of a digital-to-analog converter circuit 82, the circuit converts the received digital signal into an analog signal, which is provided at output terminal 83. Similarly, the output from digital multiplier 84 is provided via bus 86 to the address input of blue gamma correction lookup table 124,
And the information in the selected storage location is transmitted to the input of the digital-to-analog converter circuit 87 via the bus 127. The received digital signal is converted to an analog voltage, which is provided at output terminal 88. The color palette circuit 121 is particularly advantageous when used in a system that utilizes color intensity information in a color display.

An eighth embodiment of the invention is shown in FIG. 10 and includes a color palette circuit 132. Color palette circuit 132 produces analog signals at outputs 25, 28 and 31 to respectively define the red, green and blue components for the pixel to be displayed. The color of the pixel to be displayed is generated from the input via bus 17 from the video bitmap and in many respects operates similarly to the first embodiment of the invention shown in FIG. Corresponding circuit components in FIGS. 2 and 10 are indicated by corresponding reference symbols. The color palette circuit 132
Gamma correction is applied to the red, green and blue components to provide improved color rendition to the color palette circuit 16 shown in FIG. More specifically, the gamma correction look-up table 133 is used by the digital adder 2
It is interposed between 0 and the digital-analog converter 24. The bus 23 from the digital adder 20 provides an address input to the gamma correction look-up table 133 and the information contained in the addressed storage location is the bus 13
4 to the digital-analog converter 24. A gamma correction look-up table 13 is provided to provide color correction for the green component of the pixel to be displayed.
5 has its address input connected to bus 27 and the information at the selected storage location in gamma correction lookup table 135 is provided to the input of digital to analog converter 26 via bus 136. Finally, the gamma correction look-up table 137 receives at its address input via bus 29 the address for the selected storage location and the information contained in the selected storage location via the digital analog via bus 138. It is given to the converter 30. The color palette circuit 132 provides an additional level of sophistication with respect to the color palette circuit 16, which, by using the color palette circuit 132, determines the brightness of the display device as a function of the analog drive signals provided to the display device. This is because it becomes possible to compensate for the non-linearity.

The color palette circuit 142 shown in FIG. 11 represents the ninth embodiment of the present invention. The red, green and blue color components of the pixel to be displayed are the color look-up table 71, the luminance look-up table 92, the combinational circuit 7
4, 80 and 84, which are digital multiplier circuits in this embodiment, where the red, green and blue gamma corrections are the red gamma correction look-up table 143, the green gamma correction look-up table. 144 and blue gamma correction lookup table 145
This is achieved by using The digital information appearing on bus 76 for the pixel to be displayed is coupled to the address input of red gamma correction look-up table 143, and the information at the addressed storage location is transferred via bus 146 to digital to analog converter 77. Transferred to. To achieve green gamma correction, the digital signal on bus 81 is provided to the address input of green gamma correction look-up table 144,
And the resulting output from the selected storage location is provided to digital-to-analog converter 82 via bus 147. The blue gamma correction information stored in the blue gamma correction look-up table 145 is given to the digital-analog converter 87 via the bus 148, and the transferred information is the information contained in the storage position in the blue gamma correction look-up table 145. Yes, it is addressed based on digital information coupled to the address input of the blue gamma correction look-up table 145 via bus 86. By comparing the color palette circuit 91 with the color palette circuit 142, it will be understood that many circuit elements are common and therefore they are identified by the same reference symbols. The gamma correction look-up table utilized in color palette circuit 142 may be comprised of any suitable memory means, such as a solid state memory. The information to be stored in storage locations within each of the gamma correction look-up tables is determined by other parameters in the system in which the color palette circuit 142 will be utilized. The color palette circuit 142 provides greater flexibility in the display of pixels in the bitmap.

The above is a description of several embodiments for carrying out the invention. It is of course understood that the invention is not limited to the above description, but only by the claims which follow.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a typical prior art color palette circuit.

FIG. 2 is a diagram showing a first embodiment of the present invention.

FIG. 3 mathematically illustrates the general case where the first and second memories are used to increase the total number of colors that can be displayed.

FIG. 4 is a diagram showing a second embodiment of the present invention in which a displayable color is generated using input from a color bitmap and information from a saturation bitmap, where the combining means is an adder. is there.

FIG. 5 shows a third embodiment of the invention in which the displayed colors are generated using inputs from a color bitmap and an intensity bitmap, where the combining means is a multiplier.

FIG. 6 shows a fourth embodiment of the invention in which information from a color look-up table and a luminance look-up table is digitally combined to generate the color to be displayed.

FIG. 7: The colors to be displayed at the output digital-to-analog converter analogically combine (multiplicatively) the information from the color look-up table and the analog information converted from the digital information received from the luminance bitmap. It is a figure which shows the 5th Example of this invention determined by this.

FIG. 8 is a sixth aspect of the invention in which the color to be displayed is generated by analog multiplication of the color information from the color look-up table and the luminance information from the luminance look-up table.
It is a figure which shows the Example of.

FIG. 9 is a gamma correction look-up table utilized and displayed with color information from a color look-up table and luma information from a luma bitmap (a multiplier is used to combine the chroma and luma information). It is a figure which shows the 7th Example of this invention which produces | generates the color which should be.

FIG. 10: Gamma correction is provided with combined output from the first and second color look-up tables (where the combination is accomplished by use of an adder circuit) to produce the color to be displayed. It is a figure which shows the 8th Example of this invention.

FIG. 11: Gamma correction is provided and displayed with a system utilizing combined information from a color look-up table and an intensity look-up table, where the combination is achieved by using a multiplier circuit. It is a figure which shows the 9th Example of this invention which produces a power color.

[Explanation of symbols]

 16-color palette circuit 17-bus 18-color look-up table 19-color look-up table 24 Digital-analog converter 26 Digital-analog converter 54 Red adder 56 Green adder 58 Blue adder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Roy Jay Levi United States, 97520 Siskiyou Boulevard, Ashland, Oregon, 514

Claims (15)

[Claims] 1. A color palette circuit for receiving digital information from a video bitmap and converting said digital information into analog information having n components for use by other means to produce color pixels. Wherein the circuit includes a first memory means having a plurality of storage locations for storing digital information, the first memory means including an address input for receiving digital information from the video bitmap. And including circuit means for selecting a storage location in response to receiving digital information from the video bit map coupled to the address input,
The first memory means has an n output terminal for providing an n portion of digital information stored at a selected address, and an n output terminal for supplying the n portion of the digital information at a selected address. A second memory means having a plurality of storage locations for storing digital information, the second memory means for receiving digital information from the video bitmap. An address input is included and includes circuit means coupled to the address input for selecting a storage location in response to receiving digital information from the video bit map, the second memory means for selecting the selected address. N output terminals for providing the n part of the digital information from
Means for coupling the n portion of the digital information at a selected address to each one of the n output terminals, and further comprising an n digital combination circuit, each of which comprises a first
And a second input terminal and an output terminal, wherein n
Each of the digital combinational circuits includes circuit means for generating and providing a signal at said output terminal in response to receiving a signal at said first and second input terminals, said first and second inputs. Means for coupling the first input terminal of each of the n digital combination circuits to an output terminal of the first memory means, which is the result of a combination of signals received at the terminals; and each of the digital combination circuit means. Means for coupling said second input terminal to an output terminal of said second memory means, and n digital-to-analog conversion circuit, each of said n
It has an input terminal for receiving a signal from the correlation circuit of the digital combination circuit and an output terminal for giving an analog signal in response to the reception of the digital signal, and further, each input terminal of the digital-analog conversion circuit. A color palette circuit including means for coupling the output to the output of the correlating digital combinational circuit. 2. The color palette circuit of claim 1, wherein the digital combination circuit is an adder circuit. 3. The color palette circuit according to claim 1, wherein the digital combination circuit is a multiplier circuit. 4. The method according to claim 1, wherein said means for coupling the input terminal of said digital-to-analog conversion circuit to the output of its correlated digital combination circuit comprises circuit means for providing gamma correction. Color palette circuit. 5. A first input terminal for receiving digital information from the color bitmap and a second input terminal for receiving digital information from the saturation bitmap,
A color palette circuit responsive thereto to generate analog information having n components for use by other means to generate color pixels, said circuit providing digital information indicative of a displayable color. Memory means having a plurality of storage locations for storing, said memory means having an address input coupled to said first input terminal for receiving digital information from said color bit map and circuit means. For selecting a storage location in response to receiving digital information from the color bitmap coupled to the address input, the memory means for providing an n portion of digital information stored at the selected address. an n output terminal and the n portion of the digital information at the selected address for each of the n output terminals. And n means for combining digital circuits, each of which has a first and a second input terminal and an output terminal, each of said n digital combination circuits including circuit means, Generating and providing a signal at the output terminal in response to receiving a signal at the first and second input terminals, which is the result of a combination of signals received at the first and second input terminals. Means for coupling the first input terminal of each of said digital combinational circuits to the correlation of said n output terminals of said memory means, and said second input terminal of said color palette circuit for said n digital combinational circuit. Means for coupling to each of said second input terminals; and n digital-to-analog conversion circuits, each for inputting a signal from a correlator of said digital combinational circuits An output terminal for providing an analog signal in response to receiving a digital signal, the color further comprising means for coupling the input terminal of each digital-to-analog conversion circuit to the output terminal of its associated digital combinational circuit. Pallet circuit. 6. The color palette circuit according to claim 5, wherein the digital combination circuit is an adder circuit. 7. A method according to claim 5, wherein said means for coupling the input terminal of each digital-to-analog conversion circuit to the output terminal of its correlated digital combination circuit comprises circuit means for providing gamma correction. The described color palette circuit. 8. A first input terminal for receiving digital information from a color bitmap and a second input terminal for receiving digital information from a luminance bitmap,
A color palette circuit responsive thereto for generating analog information having n components for use by other means to generate color pixels, said circuit storing digital information indicative of a displayable color. A memory means having a plurality of storage locations for storing the data, the memory means having an address input coupled to the first input terminal for receiving digital information from the color bitmap and including circuit means. , Which is coupled to the address input, which in response to receiving digital information from the color bitmap, selects a storage location, the memory means providing the n portion of the digital information stored at the selected address. And n output terminals for each of the n output terminals of the digital information at the selected address. Means for coupling to said ones, further comprising n digital combinational circuits, each having first and second input terminals and an output terminal, each of said n digital combinational circuits including circuit means, said Generating and providing a signal at the output terminal in response to receiving a signal at the first and second input terminals, which is a result of the combination of signals received at the first and second input terminals; Means for coupling the first input terminal of each of said digital combinational circuits to the correlating one of said n output terminals of said memory means, and said second input terminal of said color palette circuit for each of said n digital combinational circuits. Means for coupling to the second input terminal of the digital input circuit, and an n digital-to-analog conversion circuit, each input for receiving a signal from the correlation of the digital combinational circuit. A terminal and an output terminal for providing an analog signal in response to the reception of the digital signal, further comprising means for coupling each input terminal of the digital-to-analog conversion circuit to the output terminal of its correlated digital combination circuit. Color palette circuit. 9. The color palette circuit according to claim 8, wherein the digital combination circuit is a multiplier circuit. 10. A method according to claim 8, wherein the means for coupling each input terminal of the digital-to-analog conversion circuit to the output terminal of its correlating combinational circuit comprises circuit means for providing gamma correction. Circuit. 11. A first input terminal for receiving digital information from a color bitmap and a second input terminal for receiving digital information from a luminance bitmap,
A color palette circuit for converting the digital information into analog information having n components for use to create color pixels by other means, the circuit comprising a plurality of stores for storing the digital information. A first memory means having a location, said first memory means having an address input coupled to said first input terminal for receiving digital information from said color bitmap and including circuit means, Coupled to the address input, which selects a storage location in response to receiving digital information from the color bitmap, the first memory means providing n portions of digital information stored at a selected address. And an n output terminal for transmitting the n portion of the digital information at the selected address to the n output terminal. A second memory means having a plurality of storage locations for storing digital information, the second memory means having a plurality of storage locations, and a second memory means for storing digital information. Comprising an address input coupled to a terminal for receiving digital information from the intensity bitmap and including circuit means, coupled to the address input for storing in response to receiving digital information from the intensity bitmap. Selecting a location, the second memory means has an output terminal for providing digital information from a selected address, and means for coupling the digital information at the selected address to the output terminal. , N digital combination circuits, each having first and second input terminals and an output terminal, said n digital combination circuits Each includes circuit means for generating and providing a signal at said output terminal in response to receiving a signal at said first and second input terminals, which is received at said first and second input terminals. Means for coupling the first input terminal of each of the n digital combinational circuits to the output terminal of the first memory means, and the second of each of the digital combinational circuit means. Means for coupling the input terminal of the second memory means to the output terminal of the second memory means;
An input terminal for receiving a signal from the correlating one of the digital combinational circuits and an output terminal for providing an analog signal in response to the reception of the digital signal, each input terminal of said digital-to-analog converting circuit having its correlation Color palette circuit further comprising means for coupling to an output terminal of the digital combination circuit of. 12. The color palette circuit of claim 11, wherein the digital combination circuit is a multiplier circuit. 13. A method according to claim 11, wherein the means for coupling the input terminal of the digital-to-analog conversion circuit to the output of its correlated digital combination circuit comprises circuit means for providing gamma correction. Color palette circuit. 14. A first input terminal for receiving digital information from a color bitmap and a second input terminal for receiving digital information from a luminance bitmap, responsive to other means. A color palette circuit for generating analog information having n components for use to generate color pixels, said circuit having a plurality of storage locations for storing digital information indicative of a displayable color. Memory means for activating, said memory means having an address input coupled to said first input terminal for receiving digital information from said color bitmap and including circuit means, which is coupled to said address input. , It selects a storage location in response to receiving digital information from the color bitmap, and the memory means stores at a selected address. An n output terminal for providing a portion of the digital information and means for coupling the n portion of the digital information at a selected address to each of the n output terminals, n digital-to-analog conversion and combination A circuit, each having first and second input terminals and an output terminal, each of said n digital-to-analog conversion and combination circuits including circuit means, which is a signal at said first and second input terminals. In response to the reception of an analog signal at the output terminal and which is a result of the combination of the signals received at the first and second input terminals, each of the digital-to-analog conversion and combinational circuits. Means for coupling a first input terminal to a correlation of the n output terminals of the memory means, and an input terminal and an output terminal A digital-analog conversion circuit, means for coupling the second input terminal of the color palette circuit to the input terminal of the digital-analog conversion circuit, and the output terminal of the digital-analog conversion circuit for the n-digital-analog conversion, Means for coupling to the second input terminal of each of the combinational circuits. 15. The means for coupling the second input terminal of the color palette circuit to the input terminal of the digital-to-analog conversion circuit has a plurality of data storage locations for storing color luminance information. 15. The color palette circuit of claim 14 including the memory means of.