eMagin Corporation
SXGA120-120 Reference Board
D01-500947-07 Rev A
SXGA120120 Design Reference Board User
’
s Manual
17
Figure 6-5 The Gamma Section of the Software
6.7.1. Gamma Coefficients GC(0-8)
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.
6.7.2. Preset Gamma Table descriptions
There are 3 Gamma tables programmed into the Microcontroller firmware and
can be selected from the windows software. They can be selected by using the
pull-down menu in the lower left of the Gamma section. (Preset GAMMAS) Each
table was calculated for a linear response at different luminance levels. For
instance, Table 0 is for low luminance applications.
6.7.3.
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 SXGA120 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 FPGA.
6.7.4. 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
.
