RAW or JPEG? Which one when?

It processes it, not post processes it. Processing or development is the mechanism by which you convert the latent digital image in the raw file to a viewable image. Post processing is when you take such an image and manipulate it to make a different image. Typically if I intend to do a lot of post processing work I will process the raw file quite differently, depending on what I'm intending in the PP, from if I was just going to use the processed image direct.

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Bob