I understand the concept of blown highlights but I'm puzzled by how they are treated in camera and in processing software. In the two shots below, there are some areas of cloud that are blown. The first shot shows what I'll call "normal exposure" whereas the second shot shows what happens when the brightness slider is wound down to -100 in PSE.
My question is this:
If the blown areas are given a value of 255,255,255 (white) in the jpeg file, why dont they turn grey in the second shot (eg a value of say 128,128,128) ? Doesn't the brightness control just reduce every pixel in the image by a certain amount ? Are these pixels given some sort of special tag which says to the processng software "leave these as they are" ?
Incidentally, these blown highlights were able to be recovered from the RAW file but I have not done so in the test images displayed here.