Color Space Settings In PS

[smoke665]

I was having a few minor color issues in what I saw in Ps and what I was seeing in an exported JPEG, I had the the RGB set to sRGB IEC61966-2.1 but have since changed to these settings.


I'll be doing some test prints later today, but anyone see a problem with these settings?

 

[Ysarex]

I was having a few minor color issues in what I saw in Ps and what I was seeing in an exported JPEG, I had the the RGB set to sRGB IEC61966-2.1 but have since changed to these settings.
View attachment 176775

I'll be doing some test prints later today, but anyone see a problem with these settings?

ProPhoto is the correct setting for best possible outcome. Ultimately it's a workflow issue. Consider for example that using LR Adobe doesn't provide the option to change colorspace but instead enforces ProPhoto on all users for all photos. So why the option to change working spaces in PS? Isn't Adobe being inconsistent? Then consider that ProPhoto is inappropriate for any output target as it literally contains colors beyond the capacity of human vision -- what would be the point of that? And if we can't leave the image ProPhoto for final use (we really do want final output to be sRGB or aRGB) why set it there to begin with?

Photo editing is a process of reduction. Think funnel. You pour your data into the top of the funnel which is wide and accepts lots of data and you process that data in a controlled manner to reach the output end of the funnel. If you start the process with the input end of the funnel the same diameter as the output end your options are taken away and you lose the ability to smoothly control adjustments to the data.

Adobe recognizes that LR (designed for raw image conversion) is the wide end of the funnel and so enforces ProPhoto without user option (we start with a raw file). PS on the other hand is in the middle of the funnel and there's no guarantee that what's being handed to PS came from LR. (Here's a real inconsistency in Adobe in that ACR does allow user selection of the colorspace -- it shouldn't). PS can adapt to any variety of input arriving at the middle of the funnel.

In an ideal workflow a raw file converted to an RGB image in any raw converter using the ProPhoto colorspace is handed to PS for additional processing and received by PS in the ProPhoto colorspace. When editing is finished it's Photoshop's job to handle the final conversion down to sRGB/aRGB and generate the output file at the end of the funnel.

What bad things happen if we don't adhere to the ideal workflow that begins with ProPhoto? Most of all banding especially visible in gradients. In a smaller colorspace with less steps between colors, editing changes of tone/color can generate visible banding that would not occur using ProPhoto.

Joe

 

[smoke665]

@Ysarex Thanks Joe, I thought I was correct.

 

[Tim Tucker 2]

@Ysarex, not quite...

Colour itself is not a property of light, it is how organic optical systems such as your eye interprets wavelength. This is an important concept as colour describes how the eye works and not how light works. ALL colour reproduction systems are based on the human eye.

Colourspace is a fairly simple idea and shouldn't be seen as complicated because of all the technical terms. Colour itself is perceptual but in order to reproduce it accurately within any system you must nail it to absolutes. All a colorspace does is nail colours to absolute numbers in a 3D coordinate map that's based on the perceptual colour map, or the colour wheel. This is again important as absolute colour in any reproduction system is mapped to a *perceptual* model and NOT absolute wavelength. (This conversion to the perceptual model happens at the point of capture. Lenses are designed using wavelength and the physics of light but once captured the information is stored, edited and reproduced based on a perceptual model which in turn is based on how the human eye works and not the physics of light).

ProPhotoRGB is the widest gamut and generally the best for *editing* photos, but not generally the best for other tasks. Lightroom uses it's version of ProPhotoRGB as it's a batch photo editor but Photoshop does a lot more than just photo editing and so needs the capability of editing in other colour spaces. Output colour is, in a lot of applications, far more important than editing colorspace.

Therefore the idea that ProPhotoRGB contains colours outside the visual spectrum is a false one as there are no colours outside the visual spectrum. It is the visual spectrum that defines the range of colours and not wavelength. ProPhotoRGB is a 3D colorspace that is larger than the visual spectrum which leave a problem, that it contains theoretical colours that simply don't exist and that no output device can ever reproduce. The colours don't exist, no device can display them and no eye can see them. What happens is that the colour is mapped into the space of the output system, (it's a conversion to the output colorspace or profile of the printer/monitor which represents the colours the output device can handle) and the colours outside of this are *squashed* into this space with a *Perceptual* or *Relative* intent.

This is where ProPhotoRGB can cause problems as the *squashing* from a much larger space pushes the colours further, (to get them within the output profile), and can lead to some *odd* colours in the output stage. Care is needed, if you're into a highly saturated *look* then with ProPhotoRGB you can be dealing with a lot of colours that are simply theoretical and outside the output range. Therefore a lot of colours will be converted at output and the effects are that your image can look quite different as the colours you thought you were dealing with are not the ones your output device will display.

Image editing is a subtractive process as in general it removes information, doesn't add it. It's odd as we usually just think that increasing *saturation* for example *adds* colour but in reality it is subtracting colour and information.

What bad things happen if we don't adhere to the ideal workflow that begins with ProPhoto? Most of all banding especially visible in gradients. In a smaller colorspace with less steps between colors, editing changes of tone/color can generate visible banding that would not occur using ProPhoto.

Not really, it's the other way around. Colour space is a 3D map and not linear, conversions are perceptual within this space and not linear. So there is no reduction in *steps* so much in actual colourspace but if you edit in 8bit rather than 16bit. If you use ProPhotoRGB in 8bit then you will find a lot more *posterization* because, to use a simple visual model, you leave every other step out and with a wider gamut it means more of a visual difference between each step.