On 12/30/07, Martin Spacek <[EMAIL PROTECTED]> wrote: > > Andrew Straw wrote: > > I understand Martin's question to mean that he wants to modify the LUT > > used by the RAMDAC in the video card. The shader route, or anything that > > just alters what goes into the framebuffer, is probably not what he's > > after. Instead, he's after how the framebuffer is interpreted. > > > > Digging through the SDL sources, it appears that for X11, the call is > > XStoreColors. For Windows, SetDeviceGammaRamp. For Mac OS X Quartz, it's > > CGSetDisplayTransferByTable. > > > > Hope that helps, > > Andrew > > Yeah, that's what I meant :) Andrew and I and many others use VisionEgg > (which currently relies on pygame/SDL) for generating visual stimuli for > use in psychophysics and neurophysiology. We often need to linearize the > output of the display, so that a pixel value of 255 really is 255 times > brighter (in candels/m^2, as measured by a light meter) than a pixel > value of 1. We do this by gamma correction. > > I'm looking at extending VisionEgg to use pyglet as an alternative to > pygame, so we can take advantage of multiple windows on multiple > screens. It's been very easy so far, and gamma correction is about the > only major thing I've found that's missing.
Some of the OpenGL support I mentioned is here: http://www.opengl.org/registry/specs/EXT/framebuffer_sRGB.txt. It assumes an output gamma of 2.2. It sounds like you have control over the rendering machine, in which case rendering to a linear framebuffer and using the device driver's configuration tool to calibrate the display seems more appropriate. Cheers Alex. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "pyglet-users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/pyglet-users?hl=en -~----------~----~----~----~------~----~------~--~---
