🚀 go-pugleaf

Mike,

Digital cameras capture unrendered scenes. Scanners scan rendered images from film and print (and very few of them do so at linear gamma�it's near-universal practice to apply gamma correction to the analog data to make better use of the available bits). The distinction between rendered and unrendered, or scene-referred and output-referred images is fundamental in digital image processing.

Camera Raw does all its processing in linear because, and only because, its sole purpose is to take a raw linear capture and produce a gamma-corrected image. And while I think it's an amazing piece of work, I strenuously dispute the notion that "It produces from a linear file a image that should need no further tweaking."

For the record, I much prefer doing selective, content-sensitive sharpening on the gamma-corrected image to doing global one-size-fits-all sharpening in ACR. ACR's sharpening is there as a workflow convenience, not because there's any benefit to doing sharpening in linear rather than gamma-corrected space.

Ray-tracing and some blending operations are better done in linear gamma when working with limited bit depths ("limited bit depths" being understood to mean anything less than 32-bit floating-point per pixel per channel), but to do Photoshop-type operations and have them work well in linear gamma, you'd need about 96 bits per channel per pixel to preserve adequate shadow detail, and you'd be devoting about 50 of those bits to tonal distinctions that are only detectable by instruments, not eyeballs.

If you want all your Photoshop workflow to be linear, you can do that today. It uses the gamma of the working space you choose, and it's trivial to create one with gamma = 1.0. If you really believe that there's a benefit to doing so, I suggest you try it. I suspect you'll be disappointed, though.

(It's an interesting exercise to acquire digital captures as linear�most raw converters other than ACR give you that option, then assign a gamma 1.0 profile to it. But you'll generally find that you want to convert it from the linear profile to a gamma-corrected one for any significant editing.)