site_archiver@lists.apple.com Delivered-To: pro-apps-dev@lists.apple.com Hi Pro Apps Team: Zero Saturation point 112 Maximum Cb and Cr value of 255 112/255 = .43921569 approximately .439 Does anyone know why this would happen? Brad Wright _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.ap... Here's what I did. I created a core image filter that generates a color that fills the entire screen. All this filter does is display what ever values you feed into it for the vec4 color that is returned (pre-multiplied of course). I then used the built in Final Cut Scopes to read the color values back. It appears that the color neutral point is when both U and V are at 0.42 - 0.44 depending on the value for Y. At least that's what the Final Cut Scopes are saying. I looked at both the RGB parade and the Vectorscope to verify that these values line up. I'm apply this filter directly over a video frame from an FxTexture mapped into a CIImage. I've been through the documentation and I can't figure out how Final Cut is mapping these values. The U and V values should stay color neutral while the Y value varies up or down. I'm not seeing that happening. It appears the Hue is being shifted around as the Y varies. I'm not sure how the U and V values arrive at between 0.42 and 0.44. The best I can figure is that Cb and Cr are mapped at between 0 - 224 without the offset that the documentation says there is. If I assume that the color neutral point is .42-0.44 in float point, then I can get this value by mapping: This email sent to site_archiver@lists.apple.com