Blacks crushed in sRGB on Mac? Read this.

Hi folks,

I have been struggling with a persistent problem on my Mac Book Pro, running Mavericks 10.9.5.

The basic problem is that when I edit an image with very subtle and dark shadow detail, convert it to sRGB for web display and then view the image in Preview or Safari, the blacks are crushed. If I view the sRGB image in Photoshop, no problem.

I started digging around and found these very informative posts:

http://lagemaat.blogsp​ot.com …gement-bug-in-mac-os.html

and

https://forums.adobe.c​om/message/6027420

It turns out that Lightroom users in Mavericks and apparently Yosemite (I have not upgraded) are reporting the same issue, but only in the Develop module (but not in the Library module) of Lightroom.

(EDIT: I opened the below images in Lightroom - they are BOTH DISPLAYED INCORRECTLY - blocked shadows, etc. - in the Develop module.)

I thought I was nuts, I re-calibrated and profiled my displays, checked RGB numbers and histograms, etc. etc. I may be nuts, but apparently not for the reason associated with my shadow tones getting crushed.

As speculated in the blog post to which I linked above, this appears to be a Mac/Safari (Preview?) issue. There are a couple more posts from the above blog that deal with this issue, including this one:

http://lagemaat.blogsp​ot.com …ication-of-mavericks.html

which quantifies the problem. I did similar experiments and came to the same conclusion. Crazier still is the fact that Firefox and Chrome render the sRGB tagged image correctly. Similarly, if one converts the sRGB image to AdobeRGB, the problem disappears and blacks are rendered correctly.

So, be wary if you are using Safari to view sRGB content and it seems as if your shadow tones are getting crushed. I have been trying to find a viable solution for posting my embedded images in AdobeRGB - Dropbox Public folder links will permit you to embed an image with any tag you want, as opposed to most photo sharing/hosting sites which strip the tag out or assume sRGB.

Here is a test image to see if you are affected with the issue. The top image is sRGB, the bottom image is AdobeRGB. You obviously need a color managed browser to view these images properly - they should look identical, more or less.

The number below each patch represents the sRGB R, G, B value (that is, "1" means a patch with sRGB R,G,B triplet of (1,1,1). On my display, in Photoshop, (and Chrome and Firefox) I can differentiate down into the "2" level. On Safari, the first row is more or less completely black and I can barely differentiate between adjacent patches in the second row.

Hopefully most of you will read this post and say to yourself "I can't see a difference - what the hell is he talking about?"

kirk

sRGB

Mac users, please post your experience with this here. I do not use Lightroom very often and, when I do, it is with raw images, not RGB images tagged with a specific color profile.

Thanks,

kirk

Note - I was using LR 5.4 for mac. I am currently updating to 5.6 and will report back when I update - for some completely crazy reason, the download is over 500MB. Wow.

kirk

I am running Firefox v. 32.0.3 with color management enabled on OS X 10.9.5, viewed on a NEC PA272 monitor calibrated with i1 Display Pro. As you state, I can differentiate to patch 2, although it is a little plugged. It is the same for both versions.

[QUOTE=kirkt;17249852]​Hi folks,

I have been struggling with a persistent problem on my Mac Book Pro, running Mavericks 10.9.5.

The basic problem is that when I edit an image with very subtle and dark shadow detail, convert it to sRGB for web display and then view the image in Preview or Safari, the blacks are crushed. If I view the sRGB image in Photoshop, no problem.

I started digging around and found these very informative posts:

http://lagemaat.blogsp​ot.com …gement-bug-in-mac-os.html

and

https://forums.adobe.c​om/message/6027420

It turns out that Lightroom users in Mavericks and apparently Yosemite (I have not upgraded) are reporting the same issue, but only in the Develop module (but not in the Library module) of Lightroom.

(EDIT: I opened the below images in Lightroom - they are BOTH DISPLAYED INCORRECTLY - blocked shadows, etc. - in the Develop module.)

I thought I was nuts, I re-calibrated and profiled my displays, checked RGB numbers and histograms, etc. etc. I may be nuts, but apparently not for the reason associated with my shadow tones getting crushed.

As speculated in the blog post to which I linked above, this appears to be a Mac/Safari (Preview?) issue. There are a couple more posts from the above blog that deal with this issue, including this one:

http://lagemaat.blogsp​ot.com …ication-of-mavericks.html

which quantifies the problem. I did similar experiments and came to the same conclusion. Crazier still is the fact that Firefox and Chrome render the sRGB tagged image correctly. Similarly, if one converts the sRGB image to AdobeRGB, the problem disappears and blacks are rendered correctly.

So, be wary if you are using Safari to view sRGB content and it seems as if your shadow tones are getting crushed. I have been trying to find a viable solution for posting my embedded images in AdobeRGB - Dropbox Public folder links will permit you to embed an image with any tag you want, as opposed to most photo sharing/hosting sites which strip the tag out or assume sRGB.

Here is a test image to see if you are affected with the issue. The top image is sRGB, the bottom image is AdobeRGB. You obviously need a color managed browser to view these images properly - they should look identical, more or less.

The number below each patch represents the sRGB R, G, B value (that is, "1" means a patch with sRGB R,G,B triplet of (1,1,1). On my display, in Photoshop, (and Chrome and Firefox) I can differentiate down into the "2" level. On Safari, the first row is more or less completely black and I can barely differentiate between adjacent patches in the second row.

Hopefully most of you will read this post and say to yourself "I can't see a difference - what the hell is he talking about?"

kirk

sRGB

Heh!!!!!!

ThreeHounds wrote in post #17250001
I am running Firefox v. 32.0.3 with color management enabled on OS X 10.9.5, viewed on a NEC PA272 monitor calibrated with i1 Display Pro. As you state, I can differentiate to patch 2, although it is a little plugged. It is the same for both versions.

Try Safari. My guess is you will not be so pleased.

Lightroom (especially the Develop module) is also acting really bizarre, although Adobe have acknowledged this and are apparently working on a solution:

http://feedback.photos​hop.com …clipped_shadows​_under_osx

(scroll down to the bottom if you are impatient). If you import both images into LR (I am now on v5.6) and view them in the Library they look very similar and, more or less, correct. View them in the Develop module and both look the same and crushed.

Thanks for the feedback.

kirk

Interesting. Imported the files into LR 5.4. They look similar, both in Library and Develop modules, with the sRGB version being a point or two darker reading the histograms. View them in Safari and the sRGB version shows the shadows crushed. This seems to point to an issue with Safari, not OS X or LR though, no?

Just for comparison, In firefox, Windows:

The SRGB on my Sony aperture grill I can see tonal difference in all of the squares. 1 is clearly darker than 2.

In ARGB 1-3 are (much) harder tell apart, but there is still a slight difference in all 3. 1 and 2 are very close.

Yes I see the difference in Safari (Mavericks, Mac Pro & Apple Monitor).

I'm the same as CyberDyne Systems on Windows 7, Firefox, using my 2007 Dell IPS panel (same panel that was used in the 20" Apple Cinema Dispays).

sRGB I can see all squares
adobeRGB I can see 3-15 for sure, but 1-2 are hard to notice for sure.

A comparison of Kirk's sRGB image as seen on Firefox (fully color managed) and IE (reads embedded profile but does not use monitor profile, instead uses sRGB display):

Monitor: Dell U2311H profiled with Spyder4 Pro
System: Windows 7 x64

Screen captures were assigned the monitor profile, values measured and images then converted to sRGB.

Wowser...>