. In the pinhole projection formula x = f*X/Z, y = f*Y/Z, what determines how much a 3D point's image position changes as its depth Z increases (with X, Y fixed)?
Both x and y are divided by Z, so farther points (larger Z) project closer to the image center -- the usual perspective effect.
. Why do objects nearer or farther than the focal plane appear blurred (the circle of confusion), according to this lesson?
Only points at the focal plane converge to a sharp point on the sensor; nearer/farther points spread over a disk whose size grows with distance from the focal plane.
. What happens if a raw Bayer mosaic is demosaicked assuming the wrong filter pattern (e.g. BGGR treated as RGGB)?
Since every pixel gets *some* value regardless of the assumed pattern, a wrong pattern produces a plausible-looking but strongly color-shifted image rather than an obvious failure.
. Why is naively averaging two gamma-encoded pixel values (e.g. for blending or blurring) physically wrong?
The correct approach is to decode to linear light, average there, then re-encode; averaging directly in encoded space under-represents the true blended brightness, as the lesson's black/white example shows.