[EMAIL PROTECTED] ([EMAIL PROTECTED]): > 5) Why quit with gamma? Why not do a uniform perceptual response > space, e.g. L* or GSDF ? Once you've decided to deal with the issue > it is not that hard to use a function that corresponds more accurately > to the eye response than the simple power function of the gamma > approximation.
I think it depends what you're trying to model. For antialiased text however, I think the choice is obvious. We are trying to model coverage of a pixel by an opaque object. Why use a perceptual space? In this case, we want a 50% black 50% white pixel to appear the colour of a fine checkerboard viewed from a distance. If, however, you want to perform a smooth fade between two images, using a perceptual space might be appropriate, and so maybe there should be an option for how to do the interpolation. But I'm not convinced. The standard definition of alpha is in terms of coverage, and therefore I think linear light interpolation is the best standard. > 6) What do we do with inadequate hardware support? > > Since roughly 99% of the commercial display hardware for PC's has a > very limited accurate bit depth this is a significant issue. If you > measure and adjust good consumer grade hardware into a uniform > contrast perception space you find that you only have about 7 bits of > greyspace to work with. Adding color into the mix makes things harder > still. Since the answer "Use adequate hardware" is not a reasonable > response, we need to think through a reasonable approach for dealing > with inadequate hardware. I'm not sure what you mean by this. Yes, colour accuracy is poor, but assuming a standard gamma of 2.2 is close to accurate and gives much better results than performing interpolations in linear space. What are you recommending? > (And how many people actually measure and calibrate their display > systems? And how many people actually measure and adjust for > variations in ambient lighting? I have seen enough real world > measurements to know that these steps are needed.) How does it matter? We'd still be better off if you could adjust this correctly and have everything work. I like the idea of having XFree assume a monitor gamma of 2.2 or the sRGB curve by default, and then have users use xgamma to tweak for their own monitor from that. -- Billy Biggs [EMAIL PROTECTED] _______________________________________________ Render mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/render
