
I’ve been trying to find an explanation for the colour shifts we experience when exporting from Photoshop. When we preview graphics in ImageReady or open them in our Mac browsers, they appear noticeably washed out. We found the process tremendously frustrating when building the John Smith’s website, and we needed a solution.
To be honest we’d blamed Photoshop, but it turns out the Mac itself is behind it. Ironically the problem does not arise because Photoshop is stupid, but because it is clever.
Now, professional colour management is a black art that I do not claim to know. I’ve been able to gather some information, and I’ll relate my understanding:
The Problem
- Gamma is a colour setting that is most noticeable in the mid-tones.
- The Mac ships to this day with a display gamma of 1.8. This is due to its print heritage which predates the dominance of Windows and widespread use of the Internet.
- Windows displays colours in sRGB (standard Red Green Blue) with a gamma of 2.2. This setting is a de facto standard shared by TV, scanners, digital cameras and the vast majority of computers on the Internet - which are not colour managed. This is why graphics on Windows appear darker and with more contrast than on the Mac.
- Photoshop is clever enough to display an image in 2.2 gamma for editing.
- However, it can’t possibly know how to preview your image when saving for web, because there is no single display profile for the web.
- So it takes its best guess, which is to render the image to your monitor profile (if you are on a Mac, the odds are its gamma setting is 1.8).
- You will observe a colour shift in the Save For Web window, but confusingly not when you reopen the image in Photoshop (see fourth point).
- Open the graphic in a non colour managed application (like a web browser) and the shift is visible.
The Solution
As is often the case with technology, there is no 100% Right Answer, but a series of steps and choices. You have to decide for yourself which you consider to be the lesser of evils.
Firstly, you must ensure that the working RGB space in Photoshop is sRGB IEC61966-2.1 (Edit menu / Colour Settings). The easiest way to do this would be to select an Internet preset. I’m using “Europe Web/Internet.”
Work away! What you see is what Windows users will see (barring monitor variances which can’t be accounted for). You can preview how your work will appear to Mac users by selecting (View menu / Proof Setup / Macintosh RGB) and turning Proof Colours on. There’s our colour shift…
Now we come to export and where we make our choice. There are those, such as Don MacAskill of SmugMug, who recommend setting your monitor profile to sRGB IEC61966-2.1 for an easy life. Your monitor profile will match your working space, so hey presto! No shift!
In practise, I don’t like this method. It produces an undesirable blue cast on my iMac’s screen. Buried away in Aperture’s online support docs, Apple’s recommendation is:
Unless you have a color management expert instructing you otherwise, select a 2.2 gamma and a D65 white point.
I did this – From (System Preferences / Displays / Colour) I walked through the “Display Calibrator Assistant” and created another monitor profile called “iMac calibrated.”
This is a hotly debated step. Print professionals argue that this is not a solution for them. They go on to contend that sacrificing colour quality on your Mac screen to see things in the same way that the masses do is unwise. Better to accept the colour shift.
I agree with MacAskill, that Apple is pleasing an expert minority at the majority’s expense. Print professionals are skilled at tweaking their colour settings, while the public in general are not – they just want things to work. It all seems a bit pointless if you can’t view your own work the way you intended it. I’ve retained the new profile subject to further experiments.
As Apple gets more consumer focused I expect they’ll quietly start to ship with 2.2 gamma by default.