Does the forum software for photoshopgurus.com fully color managed?

[Tom Mann]

In a recent thread on color correction, this subject came up. In that thread, the OP stated that he converted an image that used ProPhoto as the working color space within PS to Adobe RGB for posting, but an analysis of the metadata for the posted image showed that he didn't include either a color space tag or an embedded profile. This led to a brief side discussion of whether or not the forum software is color managed.

In this post, I'm going to try an experiment. I took a SOOTC (straight, out-of-the camera) sRGB from a little G12 P&S and converted it (using PS CS6) to ProPhoto and AdobeRGB. I then resaved both as new jpgs. Assuming that you are using a color-managed browser such as Firefox, then if the three images look the same, the forum software must be fully color managed. If they look different, then some point in the forum's handling of the image must not be color managed. BTW, I selected this little snapshot for this experiment, not because of its artistic appeal ;-), but simply because it has a wide range of colors, saturation and tones so it will be quite sensitive to color management problems. In addition it is the same image I used in the other thread for a slightly different demonstration.

Attachment #1 = sRGB
Attachment #2 = Adobe RGB
Attachment #1 = ProPhoto

BTW, in all three cases, I made sure that I embedded a color profile for that particular color space.

OK, let's see how this goes....

Tom M

 

[Tom Mann]

Well, I don't see any appreciable difference between the three images, so it looks like the forum software handles these three color spaces correctly. That's really good to know.


OK ... move on, nothing to see here,,,, back to your regularly scheduled programming, etc. ;-)

Tom M

PS - To see what the various versions of the image would look like if some piece of software in the chain did not handle color profiles correctly, see the examples I posted in the other thread.

 

[Tom Mann]

PS - Note that if a color space is specified, but no profile is embedded, this forum doesn't correctly render the image. Then again, as far as I know, a lot of of other image viewing software has the exact same problem.

 

[JDługosz]

Are you implying that there are two ways to indicate the color space on the JPEG file; i.e. a simple flag for common color spaces, without embedding an arbitrary profile?

If so, what is the correct way to save (a copy) in PhotoShop to make sure it sticks? Or do you use another tool to go over the file afterwards? I didn't see any option to specify a profile on saving, so I converted to AdboeRGB, reduced to 8 bit, then saved as JPEG. I checked in a non-Adobe tool to verify that it looked the same. Now, looking in more detail, I see Thumbs Plus shows Color Profile under File Properties.

 

[Remote-Medic]

I think this may be relevant Tom for this:
http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html

 

[JDługosz]

I think this may be relevant Tom for this:
http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html

That's what I read. I'm now happily using Firefox with a Dell U2711 monitor in native (larger gamut than sRGB) mode.

 

[Tom Mann]

Hi Guys -

R-M, thanks for the link. I've seen it in the past and generally agree with it.

Generally, and mostly for pragmatic reasons, this fellow recommends not embedding an ICC profile. However, if you are an advanced photographer, you also need to read this other page on his website:

http://www.gballard.net/psd/save_for_web_embed_ICC_profile.html
(scroll down about 20% to the first section highlighted in blue)

In this section, he lists a few conditions under which he recommends the opposite, ie, embedding an ICC profile. On this forum and other advanced photo forums such as photo.net, we are all evaluating images carefully. This falls into his categories #1 and #3:

"1) You are publishing technical or fine-art work — color-critical images — on the Web and are not worried about adding 4K additional data per image, per slice." and

"3) You understand only properly-profiled monitors and color-managed Web browsers will benefit from your embedded profiles — and it is likely 90% of Web surfers don't have either."

This is why I always recommend embedding a profile for discussions on advanced photography forums.

In addition, for relatively narrow gamut images like portraits, I also recommend converting (not assigning) the image to sRGB before posting. This maximizes the chances that a random viewer (ie, non-color-managed viewer, non-calibrated monitor) will see the image as close as possible to what the photographer intended, but obviously, still within the limitations of his/her equipment and software.


John, w.r.t. your question, "Are you implying that there are two ways to indicate the color space on the JPEG file; i.e. a simple flag for common color spaces, without embedding an arbitrary profile?", the answer is definitely YES. The easiest way to verify this statement is to simply open the "Save For Web" dialog box in any of the last few versions of PS (screen grab attached below), and notice that there are separate options to "Embed Color Profile" and "Convert to sRGB".

In addition, if you use Firefox, you can install an add-on called, "FxIF Data". This displays the intended color space, even if a profile is not embedded.

Finally, you also asked if I used another tool to change the embedded profile. It turns out that I did, but it wasn't necessary, I only used it for speed and convenience. Specifically, when working on the demos that I posted, I also wanted a set of images (which I haven't yet posted) that had a specified, non sRGB color space, but didn't have an embedded profile. Basically, I wanted to strip out the embedded profile from a set of images that I had already generated. I simply used Photo Mechanic to do this rather than going back into PS and outputting a completely new file without the profile.

HTH,

Tom M

 

[Steve]

If we're talking about a photograph, the color space is baked in when you take the picture.
If you shot the image using sRGB you used the smaller of the 2 spaces available to you.

Converting that image to Adobe RGB in Photoshop doesn't change the number of colors in that image, 16.7 million.
I think Adobe RGB is about 40% larger.

If you use Adobe RGB and convert it to sRGB then you literally strip image permanently of the additional gamut.
No camera I know of shoots in PhotoPro and no web browser supports Adobe RGB.

Your G12 supports Adobe RGB so shoot an image, open in in ACR and make sure you don't convert it by accident along the way.

Save it as a jpg.

Open again, convert it to sRGB and save it as a jpg with a different name.

View them in a web browser, or image viewer the sRGB image should look fine the other one should look flat and slightly desaturated.

 

[Tom Mann]

Steve: "...If we're talking about a photograph, the color space is baked in when you take the picture...."

TM: To be precise, the gamut is "baked in". The color space itself is not. It can easily be changed using the "convert to" command in PS.
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Steve: "...If you use Adobe RGB and convert it to sRGB then you literally strip image permanently of the additional gamut...."

TM: True, BUT this reduction in number of possible colors will not change the actual number of colors present in the version converted to sRGB if everything in the original image was inside the sRGB gamut. For example, as I have pointed out earlier, for well-exposed, normal contrast studio portraits taken at the correct color temperature, with a non-garish backdrop, it's extremely rare for anything to ever be out of the gamut of sRGB.

In fact, even for typical snapshooting in uncontrolled environments, it's rare for more than a small fraction of the image to be substantially OOG. This is the reason why little P&S cameras can give pleasing results (to the masses ;-)) using only sRGB. Obviously, colorful sunsets, clown's outfits, etc. can give problems, but in truth, the problems commonly seen with these subjects typically comes from exposure and dynamic range problems, not gamut problems.
------------


Steve: "...No camera I know of shoots in PhotoPro and no web browser supports Adobe RGB...."

TM: It's true that no camera shoots in ProPhoto, but lots of cameras shoot in RAW, and you can render that raw data in any competent converter to ProPhoto or any of the common color spaces, so it's equivalent to having that capability built into all cameras that can shoot RAW.

TM: Your statement that no web browser supports Adobe RGB used to be true a few years ago, but the situation has improved and continues to do so. Currently Firefox, Safari, and Chrome all fully support Adobe RGB and ProPhoto. Internet Explorer "almost" got it right. I don't use IE, but my understanding is that IE currently converts non-sRGB images with an embedded color profile to sRGB, but doesn't make use of a display profile that might be present.

If you don't believe me, go to http://www.gballard.net/psd/go_live_page_profile/embeddedJPEGprofiles.html and scroll about 75% down the page and read the sections titled: "List of Color Managed Web Browsers", and "List of un-managed Web Browsers" in the RH column, and the section titled, "Windows Color Management" in the LH column. Note the comment that as of Sept 2012, Chrome now also appears to be fully color managed. This agrees entirely with my own tests.
------------



Steve: "...Your G12 supports Adobe RGB so shoot an image, open in in ACR and make sure you don't convert it by accident along the way. Save it as a jpg. Open again, convert it to sRGB and save it as a jpg with a different name. View them in a web browser, or image viewer the sRGB image should look fine the other one should look flat and slightly desaturated...."

Before the recent improvements to browsers, I would have had no disagreement with your comment. However, see my comment (immediately above) that the common browsers are now (Dec 2012) color managed. In fact, I illustrated exactly the loss of saturation and contrast effect that you are describing in the companion thread, http://www.photoshopgurus.com/forum/general-photoshop-board/42285-color-correction.html . Scroll about 30% down the page to my post of 12-03-2012, at 02:00 AM EST.

Fortunately, the current versions of common browsers (excepting IE) will display the two images that you suggest making almost identically to the way they appear in PS, LR, Bridge or any of pro-level fully color compliant image editing applications. This means that for colors within the gamut of sRGB, the two versions you suggest making will appear essentially identical. Only the out-of-gamut colors will be different between the two.


HTH,

Tom M

 

[JDługosz]

John, w.r.t. your question, "Are you implying that there are two ways to indicate the color space on the JPEG file; i.e. a simple flag for common color spaces, without embedding an arbitrary profile?", the answer is definitely YES. The easiest way to verify this statement is to simply open the "Save For Web" dialog box in any of the last few versions of PS (screen grab attached below), and notice that there are separate options to "Embed Color Profile" and "Convert to sRGB".

Er, just because it does convert to sRGB doesn't mean that it "marks" it in the final JPEG in some way other than embedding an ICC profile.

Perhaps there are several such flags? My posted image, for example, shows AdobeRGB in the "file properties" but that FxIF tool says "uncalibrated", and looking around in Thumbs Plus I see "Color Space: Uncalibrated" under Advanced Camera under Metadata. However, it merges all sources of metadata now so I can't see if it's stored as EXIF, XMP, or whatnot. However, one image is marked in two contradictory ways that I can see! I assume that this latter setting is the original camera setting, and interpreting it as the final saved file profile is wrong.



I interpret this as being: One option embeds the profile, whatever it might be. Another option takes the step of converting from the original to sRGB, saving you the trouble of doing that first.

 

[JDługosz]

No camera I know of shoots in PhotoPro and no web browser supports Adobe RGB.

That first statement is incomplete, as "RAW" doesn't care about the color space setting the in-camera JPEG conversion uses. The real gamut of the sensors varies with the camera model.

The second statement is patently wrong. The page cited earlier explains the behaivor of modern browsers and how they might fall down on unmarked images, but they are all color managed and respect the color space when it is tagged on an image.

 

[Steve]

I didn't think we were talking about Raw files because Tom was talking specifically about sRGB but that's correct.

On browsers you're right, I was wrong.
I don't post to the web, I print what I like so I don't really pay attention to browser specs.

@Tom I went to the link you posted, I stand corrected on the browser color space issue.

 

[Tom Mann]

John, you're right, I was rushing: the presence of those two checkboxes wasn't the best way to illustrate the existence of one or more simple int tags that allow the color space in use to be specified without actually including an embedded profile.

Probably the best evidence is to simply go to the EXIF standard (eg, reproduced at http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-008-2010_E.pdf ). Scroll down to p. 42, section 4.6.5.b. It shows that provision is made to represent the color space as a short int. Unfortunately, I don't have time at the moment to look through the standard to search for other places in the metadata that it could also be represented. Also, mention in the standard obviously doesn't mean that all the mfgrs implement it correctly, or even at all.

... to be continued ... gotta run.

HTH,

Tom M

PS - I just remembered reading somewhere that some mfgrs indicate the use of any non sRGB color space by setting that short unsigned int to the max value of that field, 2^16 - 1 or something like that. I think that is when it gets interpreted as "unassigned" by exif viewers.