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US 8,300,071 B2Granted
Method for generating a gamma table
AssigneeHimax Technologies Limited
InventorsMing-Chun Ko, Shang-Chieh Wen, Chien-Hsin Li
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AssigneeHimax Technologies Limited
InventorsMing-Chun Ko, Shang-Chieh Wen, Chien-Hsin Li
Estimating the term…
A method for generating a gamma table is provided. The method is applied to a display, and the display obtains n-bit corrected gray levels [y(1), . . . , y(2m)] from m-bit original gray levels [x(1), . . . , x(2m)] by using the gamma table, wherein m and n are positive integers. The method comprises calculating the corrected gray levels [y(1), . . . , y(2m)] corresponding to the original gray levels [x(1), . . . , x(2m)] according to a gamma curve; and successively calculating differences of two adjacent corrected gray levels (y(i+1)−y(i)) and recording the differences as a plurality of gamma reference values z(i+1) (i=1˜(2m−1)) corresponding to the original gray levels x(i+1), in which the value z(1) corresponding to x(1) is y(1), in order to generate the gamma table.
A method for generating a gamma table, applied to a display, the display obtaining n-bit corrected gray levels [y2(1), . . . , y2(2m)] from m-bit original gray levels [x(1), . . . , x(2m)] by using the gamma table, m and n being positive integers, the method comprising:
Dependencies are inferred from the claim text.
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Characterised by the way in which colour is displayed: using colour palettes, e.g. look-up tables
Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping: for the purpose of adaptation to…
Improving the quality of display appearance: using tables for spatial correction of display data
Adjustment of display parameters: for control of gamma adjustment, e.g. selecting another gamma curve
About 11 months of term left · ends 17 Sep 2027 (estimated)
1. Field of the Invention
The invention relates in general to a method for generating a gamma table, and more particularly to a method for generating a gamma table by calculating and recording gamma reference values with a lower bit number from the known corrected gray levels.
2. Description of the Related Art
FIG. 1 is a flow chart of a method for generating a gamma table according to a first embodiment of the invention.
FIG. 2 is a flow chart of a method for generating a gamma table according to a second embodiment of the invention.
FIG. 3 is a flow chart of a method for generating a gamma table according to a third embodiment of the invention.
The invention provides a method for generating a gamma table. The feature of the invention lies in gamma reference values with a lower bit number are calculated from the corrected gray levels and recorded to generate the gamma table, and when gamma correction is required, the desired corrected gray levels are restored from the gamma reference values of the gamma table. Therefore, the memory space for storing the gamma table can be reduced to greatly lower down manufacturing cost of the display.
Referring to FIG. 1, a flow chart of a method for generating a gamma table according to a first embodiment of the invention is shown. The method for generating a gamma table is applied to a display. A number of m-bit original gray levels [x(1), . . . , x(2m)], such as [0, 1, . . . , (2m−1)], are selected first, wherein m is a positive integer, such as 8. In step 102, n-bit corrected gray levels [y(1), . . . , y(2m)] corresponding to the original gray levels [x(1), . . . , x(2m)] are calculated according to a gamma curve, wherein n is a positive integer, such as 10. The corrected gray levels [y(1), . . . , y(2m)] are gamma values mapped from the original gray levels [x(1), . . . , x(2m)] according to the gamma curve, and the corrected gray level y(i) is equal to ((x(i)/(2m−1))γ×(2n−1)) (i=1˜2m), wherein γ is a gamma coefficient.
Following that, in step 104, differences of two adjacent corrected gray levels (y(i+1)−y(i)) are successively calculated. According to finite accumulated test results of the system circuit board and without consideration of minus values, when m=8, n=10 and γ=2.2, the differences (y(i+1)−y(i)) are smaller than 32. That is, only 5 bits of memory space can store all the differences (y(i+1)−y(i)). If the minus values are considered, one more bit of memory is needed to record the minus symbol of values.