Blender Color Management: Frustrated? You are not alone... is this a bug?

Yesterday i got tired of seeing my saved rendered files with different colors from the original render in blender. I though it was something about 8 bits PNG files. But nop, it was about the new Color Management tools.

Lets start saying that the Color Profile in my Macbook Pro, where i did this test, is perfect calibrated. I have no problem with Photoshop nor any other software. To illustrate the problem im uploading a picture with 9 sectors. The first Column are the saved images. The Second one are the renders in the Render/UV/Image window in blender. And the Third one are the settings in the Color Management Tab.

The first row was my original problem. The color management setting are the usual ones. But my saved image differs from the original render. It is kind of pinkish compared with the bright orange i was expecting. So i decided to investigate the problem and i got here http://wiki.blender.org/index.php/User:Sobotka/Color_Management/Calibration_and_Profiling. So i followed the instructions to create a 3D LUT profile to use in Blender. The result? the second row. You can see my additional profile, which a called “Cobalto” and i could see the color in the renders as the same colors in the pictures i had saved. I thought it was the end right? now i just have to change the pinkish orange to orange eh?. Wrong. When i saved the first render the PNG was even pinker!. So i was at the beginning again.


Why the saved PNGs change when i change settings?.. they don’t store profiling info!..only what we see should change… why aren’t there any option to save renders files as seen?..

At the end i decided to turn off the Color Management Features and changed the gamma to 2.2. Result?. Third row. Orange render, Pinked PNG too. Is this frustrating? you have no idea. Same thing with greens and yellows. Renders always differ from saved files. Now at least i can see how those colors rendered with my “Cobalto” profile are going to look saved, but i haveto go back to the original settings before saving them.

Any Comments? if this is not a bug lets clear up once and for all what we have to do to make blender to work properly with the new management tools.

Do you get the same result if you save with jpg or tif format for example ?

Yes. Same thing with JPEG. I thought it was about PNG so I tried different formats. I also tested it with blender internal, cycles an yafray. Always the same result.

When you save the image, try unchecking the ‘Save as render’ checkbox.

I’m guessing you checked that Photoshop is using the display profile, but also check the image in Photoshop has an RGB profile.

Can you share the .blend ?

Right now i have the scene set with yafray. Im uploading the file. depto-yafray.blend (781 KB)
We don’t have a “save as render” button in 2.69. We have the “view as render” button in the textures tab. Maybe the button is still visible using the render internal but i don’t use it anymore.

Thank you guys for your time. We really apreciated.

I want to highlight the two important issues in this matter. Why PNG files depend on the chosen color profile when being saved? if i see orange where i should see pink, on a uncalibrated display, the info saved should be the same. Somebody else, on a calibrated display, will see orange. besides, they are suppose to be loss less with no color profile info on it. And the second question is: Why i can’t turn color profiling off?. If there is something wrong with my display, computer, or color profile, i’d should have the option to isolate the problem turning off this feature, and then save images as they are seen in the render view.

NEW INFO: I tested it with a new monitor. Same thing… And just as before there’s no problem with photoshop nor other software.

The ‘Save as render’ checkbox:-


The top one is the render window, the bottom one is Gimp:-


They look similar enough, but keep in mind the rendered image is 32 bit, and the saved one 8 bit.

I don’t know if its the ‘right’ way to do it, but it works for me. :slight_smile:

I believe colour management views the display profile as a colour space, so it translates the rendered image into ‘Display’ colour space. When you save with ‘Save as render’ on it saves it as ‘Display’, so when you then open the saved image, Photoshop assumes it is sRGB colour space and displays it ‘wrong’.

You are absolutly right!!.. i unchecked the “save as render” box and the images are very similar!, it is still quiet different than the original render but certainly not as before… being not a real solution it is definitely a nice workaround. Crazy thing is that the “save as render” box has the exact opposite meaning.

2 things i just noted unchecking that box: Using the default color profile of the sRGB device, or the “cobalto” profile i generated with the 3D LUT, the saved images of both of them looks identical… BUT, using the “Cobalto profile” the rendered image looks almost identical to the saved file, while The default profile render is very very different from the saved one.

So, to resume the workaround: From now on, in order to see a real approximation to the final saved image, i’m going to work with my generated “cobalto” profile (the link to the tutorial to generate your own is at the original post) … and the final trick is to uncheck the “save as render” box at saving to avoid weird color shifts which was my original problem.

Thanks Organic!.. you are the man!

As the author of the wiki article, I had typed up a huge post only to delete it because Organic solved the issue!

Great to hear that the issue was solved. Even more happy that it was Organic that solved it.

I have a few ideas as to your remaining questions, but I’d probably need more context. In particular:

  • Are you always viewing in a color managed viewer with your display profile attached to the output?
  • When you calibrated and profiled your display, did you calibrate as well? I know this seems redundant, but calibration is optional and it has a rather large impact on complexties, especially here.
  • When using the color managed viewer, is the source image color space being specified? Blender does not use the iCC system for color management, and as such will not tag an image as sRGB etc.

Keep slugging away at the color stuff…

TJS

:slight_smile:

That’s a good point. I forgot to mention I usually also resave the image with an image editor, to assign an sRGB color profile, to ensure its more likely to be correctly interpreted by other software.

There’s a very easy method to tag a profile to an image using ImageMagick:

But be wary of where you are getting your profiles. For example, there are a good number of sRGB profiles floating around out there. Not all are identical. See http://ninedegreesbelow.com/photography/srgb-profile-comparison.html.

TJS

:smiley:

I used to think gamma correction was a can of worms. Colour management is even more fun. Thanks :slight_smile:

The saddest part is the color management is actually very comprehensible at a lower level once we let go of some of the learned misinformation / incorrect concepts.

The layers of abstraction and the protocols / implementations make it much more challenging than it needs to be.

This is why I am keen on trying to have folks understand the low level concepts so that more information can be spread around to solve problems in a less do-this-do-that sort of manner.

It clearly has worked to some degree, as I’ve seen a refreshing amount of discussion and solutions offered regarding color management concepts that would have previously gone unsolved.

TJS