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> why is it that I have to do so manually? You can do that correction in that situation because you've looked at the image, you know what it is meant to be, an
by unfocussed_mike 5y ago
> why is it that I have to do so manually?
You can do that correction in that situation because you've looked at the image, you know what it is meant to be, and you can decide on a set of adjustments that produce something that approximates what you want, perceptually.
But without truly extensive scene knowledge, cameras can't do that automatically, and they also can't know what information that is important to the photographer that they'd be affecting if they did.
Cameras have to try to ascertain what would be middle grey in a scene and then apply a general purpose tone curve to an image, but they do not know what is in the scene.
They can't even know for sure if the photo they are being asked to take is properly exposed by any absolute definition, in fact.
[I cut out a lot of this because I don't think it's going to be easy to complete the explanation here]
- ElephantsMyAnus 5y agoNo, the problem is VERY OBVIOUSLY more severe than that. It's really as if the images were treated as linear, which they are not. (they use gamma correction)
- unfocussed_mike 5y agoHonestly, whatever your understanding is here, you should probably build a demonstration to get it across to people. Have you ever shot photographs with a colour transparency film?
- dagmx 5y agoThis is also incorrect and trivializing of the color science. Images may use gamma correction, they may not. Trying to describe it in terms of gamma is like trying to describe food in terms of saltiness alone. You're ignoring tons of other factors.
- mark-r 5y agoAny image being displayed, or encoded in a standard such as sRGB, is using gamma. It is not optional.
- lmm 5y agoSure, and any meal you eat will have a salt content (possibly zero). Doesn't mean that that tells you all the things that could be wrong or right about the meal.
- ElephantsMyAnus 5y agoNo. It isn't there so that you can use it when you choose to. All devices expect it to be used. When you skip it the colors will be wrong.
- dagmx 5y agoYou're missing the point. You can't ONLY describe color spaces in gamma differences. Gamma is just a single element of a color space. The whole trivializing sRGB into being a 2.2 Gamma versus linear is an over simplification that ignores gamut , white point, bit depth and more. That's my point. You're trivializing what color is because you clearly have not dealt with it at scale.
- ElephantsMyAnus 5y agoNo I'm not doing that, there seems to be some problem specifically there. Either the values are converted incorrectly, or not at all, effectivelly stretching about 8 fstops into the 11.6 (slightly less for video) f-stops of sRGB. You can download an alternate color scheme from Technicolor for Canon cameras that makes the colors appear fairly reasonable.
- dagmx 5y ago"makes the colors appear fairly reasonable" From what color space to what color space, and what display or print type? Now you're back to describing a average case perceptual color rather than your initial point of accuracy.
- dagmx 5y agoI meant using gamma as a conversion function. There's a whole world of color transformations outside of just gamma. Gamma is just one of many transformations, and you can have two color spaces with identical gamma transforms, but different gamuts, white points etc...
- wonnage 5y agogamma correction is compression, sacrificing data in regions where the eye is less sensitive for more precision in the sensitive ranges. images would look the same without it, you'd just be wasting bits encoding differences that the eye can't see