OpenGL gamma/brightness correction

[GreatEmerald]

Is there a way to get how much exactly is OpenGL changing the screen gamma/brightness during play? These changes are not reflected in screenshots and videos, and that's rather annoying because things look way too dark. If there is a way to tell how much is changed, then I can manually edit them to match what I see.

[Smirftsch]

no idea if this is of any use for you (simplified code):

Code: Select all

SDL_SetGammaRamp( gammaRamp.red, gammaRamp.green, gammaRamp.blue );

and:

Code: Select all

                FLOAT RedGamma = 1.0f / (2.5f * (GammaCorrection+GammaOffsetRed));
            FLOAT GreenGamma = 1.0f / (2.5f * (GammaCorrection+GammaOffsetGreen));
            FLOAT BlueGamma = 1.0f / (2.5f * (GammaCorrection+GammaOffsetBlue));
            
            for (u = 0; u < 256; u++) 
            {
                  int iVal;
                  int iValRed, iValGreen, iValBlue;

                  //Initial value
                  iVal = u;

                  //Brightness
                  iVal += brightness;
                  //Clamping
                  if (iVal < 0) iVal = 0;
                  if (iVal > 255) iVal = 255;

                  //Gamma
                  iValRed = (int)appRound((float)pow(iVal / 255.0f, rcpRedGamma) * 255.0f);
                  iValGreen = (int)appRound((float)pow(iVal / 255.0f, rcpGreenGamma) * 255.0f);
                  iValBlue = (int)appRound((float)pow(iVal / 255.0f, rcpBlueGamma) * 255.0f);

                  //Save results
                  gammaRamp.red[u] = (BYTE)iValRed;
                  gammaRamp.green[u] = (BYTE)iValGreen;
                  gammaRamp.blue[u] = (BYTE)iValBlue;
            }

while Brightness refers to the value in the ini in [SDLDrv.SDLClient], from 0.1 to 1.0

[GreatEmerald]

Huh, that's 0.5 by default, so it just adds +0.5 to each colour component? That's not a whole lot... And also looks like it doesn't translate to [url=http://en.wikipedia.org/wiki/YUV]YUV[/url] (which is what videos are using) well at all, because Y reacts to G much more than to B :\ Oh well, it looks like having it approximated through YouTube enhancements is probably the best way to go anyway.