Thanks for the answer. Unfortunately, cropping to extent did not solve the problem. I found the real problem is another filter in filter chain that does a source over compositing, with compositing being done with a background image that is larger in size. The red pixels are filling the extent of that background image. No idea why the redKernel is being called for every pixel on the screen.

I have filed bug report FB9877123 . Waiting to hear from Apple Engineers.

I see this problem is reproducible only when playerItem.seekingWaitsForVideoCompositionRendering = true is set. Otherwise I have not been able to reproduce it so far.

It will take time to prepare a minimally reproducible sample code, I shall definitely do that. But in any case I need a workaround or alternative way to detect seek has finished.

I think in this case, CIContext may also need to be initialised with metalDevice, correct?

@YuAo, I saw your kernel code. I don't understand why 0.5 offset has been added in both x and y coordinates when you compute `vec2 redCoord = samplerTransform(toneCurveTexture,vec2(textureColor.r * 255.0 + 0.5 + toneCurveTextureExtent.x, toneCurveTextureExtent.y + 0.5)); ?

Why do we need to add 0.5 offset I wonder?