Color Theory question: Calibrated screen shows same image different

agunther

I hope I can describe this accurately enough so that the experts can give me advice. In any case, I ask for your patience as I describe this issue that plagues me.

I calibrated my Laptop screen with a Spyder 2 and get decent (although not good) results in Photoshop and other applications that utilize color profiles, but outside Photoshop, especially in a web browser the results seem worse than before. I think I understand that the calibration consists of two parts (a modification of the color lookup table of the graphics card and the color profile which Photoshop uses and the browser does not).

So far that did not concern me very much, but then I uploaded one of the pictures to flickr (first picture below) and compared it to the one from my wordpress blog (second picture below) and noticed, that the same picture looked wildly different, depending on the server that delivered the picture.

As I am writing this on a different computer, both pictures look identical. Maybe it is the computer or the black background of the forum.
Do you see any differences? How can you explain those?

Second problem that bugs me a lot: When I open a picture straight from the camera it looks about equal across all monitors (calibrated or not), but when I boost the saturation I notice significant differences between the screens. Why do these differences only show after the editing process?

agunther

Just tried again on my laptop. Both images look very different, although they are the same image delivered from different webservers (I uploaded one to flickr with a watermark, resized and uploaded the other to wordpress). On almost all computers they look identical except on this laptop. Weird. Anyone seeing this too?

D'Buggs

I's pretty sure that I'm seeing the same contrast and tones..... One seems a little softer than the other.
I run a cal'd LaCie. Don't know what's happenin' on your end.

pyry

agunther wrote:

Just tried again on my laptop. Both images look very different, although they are the same image delivered from different webservers (I uploaded one to flickr with a watermark, resized and uploaded the other to wordpress). On almost all computers they look identical except on this laptop. Weird. Anyone seeing this too?

Can you check which color space this image has been assigned to?

arodney

agunther wrote:

I think I understand that the calibration consists of two parts (a modification of the color lookup table of the graphics card and the color profile which Photoshop uses and the browser does not).

Sort of. ICC aware applications need certain info to provide a correct preview (all other factors in consideration such as, a good colorimeter and software, proper calibration target values etc). The app’s need to know the color space of the display in its current behavior. That’s what the Spyder is doing. The app’s also need to know the color space of the document. Using these two profiles, ICC aware applications use what’s known as Display Using Monitor Compensation. This is a unique preview tweak to account for all the dissimilarities between various displays (which is described in the display profile) along with the consistent information about the scale of the RGB numbers in the document (embedded profile) such that what you see and others see match and are correct.

Outside of ICC aware applications, the RGB numbers in a document, without regard or information about the color space of that document, simply get sent directly to the display. The process has no idea about the display profile nor the color space of the document. Adobe RGB (1998), sRGB or for that matter any color space is unknown, the RGB values in the display are simply sent directly to the display and preview incorrectly.

So there’s more to all this than just the LUT’s downloaded to the graphic card. Many users assume that because they calibrated the display, that these LUTs are in effect, the previews should be correct outside ICC aware applications. But without the ability to decipher the two ICC profiles necessary to produce a preview (display and document), that’s not the case.

You need to be working with one of the two ICC aware web browsers (Safari or FireFox) otherwise, what you see previewed is just incorrect and doesn’t match Photoshop and all other ICC aware applications. There’s no way to “fix this” otherwise.

Wil Davis

I've looked at the two pics posted here using Opera (10.01), Firefox (3.5.3), IE (6.0.2800.1106), PhotoShop 7.0, ACDSee (7.0 build 102), and I really can't see any difference (must be these old eyes…)



- Wil

malch

Very interesting.

The larger image has an embedded profile (sRGB) and the smaller image does not have any profile.

Viewed in Internet Explorer, the colors in both images look identical.

Viewed in Firefox, the colors look quite different.

So, then I took the larger image into Photoshop and made a copy with no embedded profile.

If I compare the two images (larger image with and without the embedded profile) they look identical in Photoshop and different in Firefox.

So, we either have a Firefox bug, or we have both failed to configure Firefox correctly.

I've seen a bunch of discussions about the color management in Firefox and this is maybe related. The original color management code (LCMS) first released at 3.0 was ditched at 3.5 in favor of the much faster QCMS code. This brought a number of controversial color management issues to the surface.

Just found this thread which suggests some problems in Firefox have been fixed and others have not. It's pretty confusing and I haven't deciphered the entire thread yet:

https://bugzilla.mozilla.org/show_bug.cgi?id=497363

agunther

Thanks everyone for your insightful comments and your time. I am stunned by the amount of support one can find on this forum by dedicated individuals such as yourselves. Amazing

Wil: Thanks for your trouble, I appreciate the input!

arodney: If I understand your post right, we have pretty much the same idea how things work. You took more time to explain it much more eloquently than I ever could. Thanks!

malch: I think you found it. I used to run my images through an automatic Irfanview resizing process, in which I intentionally removed the profile information and all other information. I did this to optimize file size, under the assumption that a missing profile would always be interpreted as sRGB color space.
I am wondering if this assumption is inherently false, and if I should include the color space information, or if I should disregard this as a browser bug.

I am also wondering why the differences are greater on edited images vs. unedited. I assume its simply because I "boosted" the color contrast to be much closer to the full range and thus the effect is simply more pronounced. What do you guys think?

Thanks again everyone!

malch

agunther wrote:

malch: I think you found it. I used to run my images through an automatic Irfanview resizing process, in which I intentionally removed the profile information and all other information. I did this to optimize file size, under the assumption that a missing profile would always be interpreted as sRGB color space.
I am wondering if this assumption is inherently false, and if I should include the color space information, or if I should disregard this as a browser bug.

Yes, I think it's preferable to leave the sRGB embedded profile in all images. It is pretty small and appears to avoid some pitfalls.

As for the browser bug, I made inquiries elsewhere and got a swift response and solution. In the URL box of Firefox, enter about:config.

Now look for this setting/parameter:

gfx.color_management.mode



0 means it's disabled
1 means it's full color management
2 means it's done only to tagged images (the default)


Change it from 2 to 1 and I think your problem will be solved. I'm guessing that you need to restart Firefox for this to take effect.

The default value of 2 seems a bit silly but I guess it reduces the performance overhead color managing lots of tiny web graphics that don't need a whole lot of color accuracy.

Eia

malch wrote:

Yes, I think it's preferable to leave the sRGB embedded profile in all images. It is pretty small and appears to avoid some pitfalls.

As for the browser bug, I made inquiries elsewhere and got a swift response and solution. In the URL box of Firefox, enter about:config.

Now look for this setting/parameter:

gfx.color_management.mode



0 means it's disabled
1 means it's full color management
2 means it's done only to tagged images (the default)


Change it from 2 to 1 and I think your problem will be solved. I'm guessing that you need to restart Firefox for this to take effect.

The default value of 2 seems a bit silly but I guess it reduces the performance overhead color managing lots of tiny web graphics that don't need a whole lot of color accuracy.

I went around and around with this several months ago. I use FF, IE, Safari and they all looked different. IE looking the closest to the calibrated monitor and colors that I use in NX. I just tried your suggestion in FF but changing between 1 & 2 showed no significant difference. I then changed it to 0 (gulp) and wow - it looks like the way my pictures are while working on them. How can that be? And should I not keep it at 0?

arodney

Eia wrote:

I just tried your suggestion in FF but changing between 1 & 2 showed no significant difference. I then changed it to 0 (gulp) and wow - it looks like the way my pictures are while working on them. How can that be? And should I not keep it at 0?

They look the same and all are wrong! What you did was disable color management in FireFox so it matches IE which was never color managed.

agunther

malch wrote:

gfx.color_management.mode

Awesome suggestion. Thanks for your work (again)
I will give it a shot tonight.
However, this is very unsatisfying. I want my images to look good on John Doe's computer who accidentally stumbles across my website. I am not Ansel Adams (yet ), so I need to make an impression right away. I can't ask a visitor to futz around with their browsers.
Most people would probably assume I would want to hijack their machine or something (manual virus).
I think the solution is to embed color profiles in all images and hope people have decent monitors.

Thanks!

malch

agunther wrote:

However, this is very unsatisfying. I want my images to look good on John Doe's computer who accidentally stumbles across my website.
I think the solution is to embed color profiles in all images and hope people have decent monitors.
Thanks!

Yes, the best you can do today is (1) to include the embedded ICC in your images (2) make sure that profile is sRGB and (3) encourage your friends and other users of your site to use Firefox, Safari or some other color managed browser.

The current situation is far from perfect. Nevertheless, on the positive side we are making progress. A year or two ago, almost no browsers or consumer level image viewers were color managed at all. If you wanted accurate color, you had to use Photoshop or some other relatively high end application. At least we're moving in the right direction.

arodney

malch wrote:

Yes, the best you can do today is (1) to include the embedded ICC in your images (2) make sure that profile is sRGB and (3) encourage your friends and other users of your site to use Firefox, Safari or some other color managed browser.

And calibrate and profile their displays. All of the above will not work if the user viewing the images doesn’t have a good display profile which those browsers use to produce a preview.

malch

arodney wrote:

And calibrate and profile their displays. All of the above will not work if the user viewing the images doesn’t have a good display profile which those browsers use to produce a preview.

Good luck with that. Sure, any serious photographer should use a calibrated monitor but it's not realistic to expect casual visitors, family and friends to go to those lengths.

arodney

malch wrote:

Good luck with that. Sure, any serious photographer should use a calibrated monitor but it's not realistic to expect casual visitors, family and friends to go to those lengths.

That’s fine, as long as the pro photographer uploading their images understand this.

TheSuede

The problem with sRGB in different browsers is that even if sRGB is the closest "idiot match" to most screen's "natural output", two pictures - both identical - one with the icc profile intact and one stripped of the profile WILL look different in two browsers.

If the browser is colour-aware, then it will try to take the picture colours through a transform into your measured monitor profile, and display this transform.

If the browser is NOT colour-aware, then there is no input profile, hence nothing to transform "from". No transform can then be done, and the picture data is sent to screen just as they are (but still passing through your graphics card's LUT).

If you have profiled your monitor/system, changes may have been made to the standard output LUT in the graphics card render engine, and this may change your "default, unmanaged" colours a bit. Normally this change should only affect non-linearities in the screen response, and this is good for all applications.

If your calibrated workflow looks "worse" than your un-managed workflow, consider that it may indeed be you yourself that's the failing part in the system. Consistent colour is what calibrating/profiling is all about, not "good" colour. Good colour is YOUR responsibility, not the computer system's. Working on a calibrated system, and making sure that your output is sRGB and as "correct with regards to the average screen" is all you can do when a picture passes outside your own workflow...

If you open a picture that you know has an Adobe RGB icc-profile embedded in Photoshop AND in your browser, and they look the same, your system is doing the right thing. If you turn off colour management in Firefox, and the pictures DON'T look the same it is also doing the right thing. That the "right thing" that PS and Firefox is doing is the CORRECT "right thing" is your responsibility, and your setup.

Eia

So then... I have my monitor calibrated (using spyder). I bring a photo up to work on in Capture NX. It is using the monitor calibrated color (spyder). However; there are other color profiles I could choose within NX such as: nikon srgb 4.----, srgbiec, and a few I downloaded for places where I get prints. The question; while working in NX, do I leave the color calibration at Spyder that I used to calibrate my monitor - or - do I choose the nikon srgb or any others?

arodney

Eia wrote:

So then... I have my monitor calibrated (using spyder). I bring a photo up to work on in Capture NX. It is using the monitor calibrated color (spyder). However; there are other color profiles I could choose within NX such as: nikon srgb 4.----, srgbiec, and a few I downloaded for places where I get prints. The question; while working in NX, do I leave the color calibration at Spyder that I used to calibrate my monitor - or - do I choose the nikon srgb or any others?

There are two profiles at play in all ICC aware applications. 1 is the display profile built by your Spyder and used for previews along with, 2, the iCC profile of the document (sRGB, Adobe RGB (1998), etc).

mikegs

arodney wrote:

There are two profiles at play in all ICC aware applications. 1 is the display profile built by your Spyder and used for previews along with, 2, the iCC profile of the document (sRGB, Adobe RGB (1998), etc).

So in this instance the system (calibrated monitor and ICC aware app) understands what we see on the monitor from the calibration profile, understands what we want as final output (say Capture NX/LightRoom/Photoshop is set to sRGB) and is compensating when we are looking t the image in the editing program understanding the difference? The system is saying user is looking at monitor with profile A, editing for profile B, therefore I will show the image in (look and feel) C which is the concatenation of A and B?

arodney

mikegs wrote:

So in this instance the system (calibrated monitor and ICC aware app) understands what we see on the monitor from the calibration profile, understands what we want as final output (say Capture NX/LightRoom/Photoshop is set to sRGB) and is compensating when we are looking t the image in the editing program understanding the difference?

Yes. Its called Display Using Monitor Compensation. Each display undergoes a unique compensation (like a camera CC filter) to produce the same previews from the same RGB values despite differences in each display.