I’ve noticed some software allows a working profile of something other than sRGB (ProPhoto; AdobeRGB, etc…), which is great for wider gamut images. But wouldn’t this be wasted if you didn’t export your image to the same profile?
For example, if I work on an image using ProPhoto, but export as sRGB, won’t I loose all of that wide gamut detail gained while working in ProPhoto? And if so, why wouldn’t I just use sRGB as my working profile if I was planning on exporting as sRGB?
Hoping someone can explain this for me in fairly plain English.
You should work in the widest gammut that you’ll utilize. For instance you can work in ProPhoto and export a tif in ProPhoto to send to a printer, then export an sRBG jpeg for the web.
You want to use the widest gamut possible for editing so that when you are pulling colors and changing things, you have the most leeway before bad things start to happen.
Then, if you’re moving to a smaller colorspace, save the conversion into that colorspace for the last step. This wayy ou only have to do the (lossy) conversion to a smaller colorspace once and can retain as much quailty as possible.
Working in sRGB will sometimes not give you enough leeway in color manipulations before bad things start to happen.
This is sort of along a similar reason for shooting and processing raw vs. jpg. Try to start and retain the highest quality and leeway during processing, and save the export to a smaller color space for the last step.
Continue reading below, I was mistaken.
On another note - do you always plan on sRGB being the target color space? Or could you think of a possible reason in the future you might want the wider gamut maintained (printing possibly)?
Color banding when you run out of colors to pull around? At least in a wider gamut you can pull it around and do the mapping to a smaller color space as a last step (hopefully getting the target tones closer to the intention?).
That doesn’t fix the problem of color banding in a lower color space, but it can let you get your colors adjusted first.
[edit] - I may be mixing color space gamut with bit-depth representation. Not sure if it will do what I think for sure, but am too busy chasing two kids around alone atm to check…
I usually get printing done at a consumer print place, not done at home. Would such places work with ProPhoto colour spaces? I thought, at best, they could only handle Adobe RGB (which is why I’ve been using Adobe RGB).
Could this also account for the dull colours in printed photos?
The colorspace gamut is only part of the problem of choosing the “best” RGB working colorspace, and is actually less of an issue now that GIMP and other editors can perform unbounded color corrections in floating point precision.
I’ll try to explain my point of view: in floating point format, out-of-gamut RGB colors have at least one component which is lower than zero or higher than one. However, as long as the editing software can deal with such out of bounds values, such colors are not lost and do not produce banding, because no clipping occurs in the editing process.
In other words, unbounded sRGB can represent as many colors as ProPhoto, if values <0 and >1 are handled correctly. This is the philosophy behind GIMP’s choice of unbounded sRGB are the “universal” working colorspace.
So why one should still bother about this issue? The point is that a working colorspace is not only used to represent RGB colors, but also to edit them. And that’s where the differences become visible, even in unbounded processing.
Whenever you edit an RGB triplet (for example multiplying it by a common factor to increase or reduce the brightness), you might (and usually will…) introduce an HUE shift as well as a change in color saturation. Generally speaking, the wider the gamut of the working colorspace, the smaller will be the change in HUE and saturation. However, this change is also influenced by the primaries of the colorspace (the corners of the triangular shape defining the gamut boundaries in the xy plane), as well as the colorspace’s gamma encoding.
If you are interested, in few days from now (when I will be back from vacations) I will try to give numerical examples of what I have tried to describe above… until then, you might look into Rec2020 and ACEScg as possibly better alternatives to ProPhoto as wide-gamut working colorspaces…
Fitting colors from a wider gamut into a narrower gamut requires squeezing them or chopping them off, and the user should be in control of what exactly happens to the colors, how they are squeezed or chopped off. When you open a raw photo in an image editor, it maps the colors into the working colorspace, and from this point you can perform all the color operations the program permits before saving the image. If you use a wide working colorspace but intend on saving to sRGB, you can decide what you want to happen to the colors which lie outside of the sRGB gamut - you can change the hue, saturation or lightness of only the outliers if the software permits, or you can make changes to all of the colors in the image, for example reduce saturation globally, so that the end result fits in sRGB. You’re in charge.
If, on the other hand, you opened your raw photo and used sRGB as the working space, you would have lost the control of what happens to the extreme colors. The “rendering intents” would be your only weapon.
Compare a photo of a hibiscus or a LED-lit concert in sRGB vs some wide gamut - the difference is striking. The fate of the extreme colors would be taken out of your control if you didn’t use a colorspace which could handle them.
That’s the way I see it.
I’m curious how ProPhoto compares to unbounded sRGB or to Rec2020 as working spaces, if we assume that the program uses floating-point throughout.
