Pixel Tape Gamma
Posted: Sun Aug 12, 2018 4:31 am
I've done some tests and I see that my pixel tape is driven with a linear change in duty cycle with DMX values.
Since video data is stored with a non-linear encoding (say a gamma of 2.2) good video presentation will require a mapping of those brightness values, which I guess is related to the Response slider, but since it doesn't show gamma values, but rather a percentage, I can't be certain.
For anyone curious I tested the strip LED by connecting a light sensor to an oscilloscope and looked at the waveform. The sensor I am using has a logarithmic response and also a slower release, but the results are clear here driving at 128, 64, and 192 that the duty cycles were about 50%, 25%, and 75%.
I was very much hoping that the driver chip was doing some kind of gamma mapping itself, which would put more brightness steps in the lower brightnesses.
Since video data is stored with a non-linear encoding (say a gamma of 2.2) good video presentation will require a mapping of those brightness values, which I guess is related to the Response slider, but since it doesn't show gamma values, but rather a percentage, I can't be certain.
For anyone curious I tested the strip LED by connecting a light sensor to an oscilloscope and looked at the waveform. The sensor I am using has a logarithmic response and also a slower release, but the results are clear here driving at 128, 64, and 192 that the duty cycles were about 50%, 25%, and 75%.
I was very much hoping that the driver chip was doing some kind of gamma mapping itself, which would put more brightness steps in the lower brightnesses.