Is there a reason not to remove colour profiles from images on the web?

Question

I have started using Jeffrey Friedl's lightroom plugin for publishing to Flickr in conjunction with the metadata wrangler which offers an option to remove the ICC color profile. However there is a note against this, saying

It's generally best to preserve the color profile, unless you have a specific reason not to.

However my understanding is that all web browsers will assume by default that the colour space is sRGB if this is not present, and some will use sRGB even if another colour space is specified. Are there any specific reasons why it might be a good idea to keep this in?

Answer 1

If the original ICC profile is sRGB or equivalent, there is usually no harm from removing it.

• sRGB is sometimes added to images that were not originally color managed. (The profile shouldn't be included with the image in the first place.)
• sRGB corresponds to the full color range of unmanaged systems. (Whether the image is tagged or not, it will appear the same when displayed.)

• sRGB is usually the default of unmanaged images on managed displays. (The image will be displayed the same regardless of whether it is tagged.)

• Some software (GIMP) will ask to convert sRGB to its built-in sRGB profile. The dialog and subsequent "conversion" is just a waste of time.

However, if the profile is for any other colorspace (like AdobeRGB), the colors will be displayed incorrectly (with the wrong colorspace) if the profile is removed. You state that the colors may be displayed incorrectly anyway. But that is a software configuration issue that can be resolved. If you remove the profile, you become the cause of the problem, as well as make it impossible for anyone who doesn't have the original image with profile to display it as intended.

Answer 2

However my understanding is that all web browsers will assume by default that the colour space is sRGB if this is not present...

Well, perhaps all web browsers should assume by default that the colour space is sRGB if this is not present, but unfortunately it's not really practical to insure that every variant of all of them do, particularly with those that are open source and easily modified by the end user. Even if all of them do now, there's no guarantee that someone won't create one in the future that does not.

Yes, you're probably correct in 99.999% of cases that in the absence of a color profile a web oriented application displaying an image will assume it is sRGB.

But what happens if someone copies/downloads a web distributed image with no color profile and then later imports it into another type of application, like say a desktop publishing program, that is set to assume something other than sRGB as its default setting?

Answer 3

Unfortunately, not all browsers will assume sRGB for untagged images. Some will instead not colour manage that image, with disasterous results on wide-gamut displays.

For example, Firefox has a setting gfx.color_management.mode, which in its default mode 2 will do exactly that. (I haven't checked if newer Firefox still respects that, because this is a direct violation of the W3C recommendation, but the default value is still 2, unfortunately).

Basically, if unsure, always keep the profile.

There are cases though when this is unreasonable. Small images such as icons usually don't require exact colours, whereas attaching a profile to them may easily double their binary size.

Or, if you actually didn't manage colours on your display when preparing the image, it is more honest to remove the profile (if there was any) to signal that.