Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: Oldfox on December 22, 2011, 07:08:00 am
-
I have an image in sRgb (tagged). I open the image in PS4 (AdobeRgb as the working space) and preserve the embedded profile. So far ok.
Then I convert the image into Lab mode, edit it and convert back to RGB.
My question: is the image in sRgb or AbodeRgb space?
colorsettings attached
-
If you have converted to LAB it is no longer and RGB image so RGB color space tags are meaningless.
-
I have an image in sRgb (tagged). I open the image in PS4 (AdobeRgb as the working space) and preserve the embedded profile. So far ok.
Then I convert the image into Lab mode, edit it and convert back to RGB.
My question: is the image in sRgb or AbodeRgb space?
colorsettings attached
Why don't you simply go into Photoshop, perform the steps, and see what you get? If you open the image and preserve the tagged profile, the image will be in sRGB. When you convert back to RGB, your default working space is Adobe RGB, so the image would be converted to that profile unless you override the conversion. If you use Edit, Convert to Profile, the default working space (Adobe RGB) will be suggested, but you can override and choose another space. If you use Image, Mode, RGB, the image will be in the default working space which is Adobe RGB and you will not be presented with a choice of color space. For this reason, it is best to always use Edit, Convert to Profile.
The above is for PSCS5. I think PSCS4 is similar.
Regards,
Billl
-
Based on your color settings, it is Adobe RGB since that is what you selected as your preferred RGB working space. If you use the Mode change (which I don’t recommend), Lab converts back to RGB based on what you set here. IF you instead used Convert to Profile, you can select any profile you wish for that conversion.
As to WHY you’d go from Adobe RGB to Lab and back, that’s another post.
-
Ah! I missed that part about going back from LAB to RGB. If your working space is Adobe RGB(1998) that is the color space the image should be in after converting the LAB version back to RGB. I just confirmed that by opening an sRGB JPEG in Photoshop CS 5 (PsCS5) converting it to LAB andthen converting it back into RGB. Once back in RGB the profile for the photo was in the working space iuse for PsCS5, Pro Photo RGB.
As for why go to LAB in the first place, I have been runnign some experiments following Lee Varis' multilayer and multip le document copies 10 Channel Color Workflow where you first work on an iamge in RGB to set tonal relationships, make a flattened copy of the document and convert the duplicate to LAB, adjust color via the A and B channels (again using multiple layers), make a top layer o f the LAB version which contains the changes i nthe eaprevious LAB layers and add that layer asa new top layer in the layer stack in the original RGB docment , make a second duplicate which you convert from RGB to CMYK, and then work withthe K (black channel) to get rid of the over saturation in certain colors, make a new top layer con tainignthe changes in the lower CMYK layers and copy that top layer back as a new top layer in the original RGB document.
The workflow is a little tricky and for some (not many actually)in my canon of work it is a useful technique for controlling the shape and feel of the image. it is not something I can recommend doing with every image and practice (i.e. screwing up until you get a feel for what you are doing) is necessary. If you want to explore it check out go to: http://varis.com/video-tutorials/
I need to point out that I recently tried this 10 (really 6: Red + Green + Blue + A + B (in LAB) + K (black) in CMYK) on a Texas Hill Country landscape but ended up with better ( more visually appealing ) color by trying different camera calibration "profiles" in Lightroom 3.6 and just working with a single RGB document when post processing in PsCS5.
-
Thx all for the answers. As hindsight, of course it is AdobeRgb, I should have thought more...
@andrew, you would make a good consultant! (or maybe you are one). You ask questions beyond the original question. I suggest it "maybe in another thread".
/fox