D01-501106-01 Rev B
DSVGA Design Reference Board Manual
13
The 9 boxes in the Gamma section represent the 9 segment piece-wise-linear
function that defines the gamma curve. These 9 values are used to calculate the
256 element
look-up-table (LUT) that is required to transform input video data into a
gamma-corrected data signal for the microdisplay input port. The “Read” button will
retrieve the current 9 values from the microcontroller. The user can change any of the 9
values and see the resulting gamma corrected video by pressing the “Write” button.
6.6.2.
Using “Update LUT” Button for Auto-Gamma Correction
The software allows for the immediate update of the gamma tables with the push
of a button, “Update LUT”. This button, located in the center of the software
form, tells the firmware to calculate the Gamma coefficients using the VGN
signal provided by the DSVGA microdisplay. This feature allows the display
gamma to be automatically adjusted for any operating conditions of temperature
and brightness. The firmware calculates the 9 Gamma coefficients and then the
full 256 value lookup table. This lookup table is then loaded, by the firmware,
into the DSVGA Microdisplay.
6.6.3. Loading the LUT from a file
The software allows for the loading of the gamma tables from a text file. The
format is as follows;
1
174
396
529
575
583
591
599
607
612
618
.
.
1023
Each of the 256 values is on a separate line. This lookup table is then loaded, by
the firmware, into the display.
6.6.4.
The “Read LUT” Button
The software allows for the reading of the full 256 values of the LUT using this
button. The result is displayed in the message box at the bottom of the software.
The user can scroll through all the values or select and save to a text file. These
LUT values are the values before being gray-coded.
