Posted by Rob Graham on February 22, 2012 at 2:47 PM
Recently, when converting my 7D files in ACR and CS5, some of the files are showing strange posterization. This posterization doesn't show up when viewed in DPP, FastStone Image Viewer, Irfanview, and IE9.
I converted this file in DPP, exporting as 16 bit tiff. The posterization wasn't evident then, but does show up in CS5 and ACR, and on this site when viewed in Firefox. Exposure and lens don't matter, as I have seen this in several different files. I don't remember this being a problem before, and haven't made any changes to my system recently.
The attached picture is a straight conversion in DPP, with nothing done during conversion. I resized in CS5. The posterization is visible in CS5 even in the shrunk version, showing up cyanish bands across the sky at top of the rocks. The rocks are also more contrasty in CS5. Is this visible or not visible to others here? Any ideas on why it only shows up in certain programs? I assume it has something to do with color management. I don't use any special profiles with my monitor, but the prints turn out fine. Thank you.
Posted by Rob Graham on February 22, 2012 at 3:07 PM
I think I found the answer, but I will leave this thread up as a learning lesson to others. I started thinking about profiles after I wrote the last sentence. I went and checked the Proof Setup menu in CS5. Somehow, it was set on Working CMYK. When I reset it to monitor RGB, the colors went back to normal and matched the other viewing programs. The attached file is a resaved version.
However, ACR is still showing the posterization. I reset the defaults, and deleted the .xmp file. What else do I need to do?
EDIT: the posterization is still evident in the repost, though it looks fine in CS5 now. What gives?
Most likely there is a color in your image that is being converted to the cyan that you are seeing. I suggest that you set ACR and your Preferences in Photo Shop to Adobe RGB 1998, Relative Colometric and Blackpoint Compensation. Don't use Monitor RGB at all because it typically has a narrow gamut, is specific to your monitor, and if your monitor is uncalibrated, color will be inaccurate.
Open the converted tiff image in Photo Shop. Go to Edit>Convert to Profile to see what the working color space is. If the working color space is anything other than Adobe RGB, convert the file to that color space. Next, duplicate the file and go to Image>Mode and be sure that 'RGB Color' and '8 bits/channel' are checked. Flatten the image, convert the profile to sRGB, resize and sharpen as needed. Now, go to File> Save for Web and Devices. Be sure that 'Embed Color Profile' is checked. Save the image.
If your preferences are correct and you've embeded the correct color profiles, the banding should be gone.
I finally figured out what was going on. Somewhere along the way, my Win7 color calibration profile must have been corrupted. I know I should get a Spyder or something similar, but haven't. I ran the Win7 color calibration routine, and everything is looking as it should. Color managed and non-managed programs are all showing the same image now :). I looked back at some family photos from last fall that printed lighter than I thought they should, and now the on screen image matches the print. Evidently this issue has been around longer than I thought.
Discussion
3 repliesI converted this file in DPP, exporting as 16 bit tiff. The posterization wasn't evident then, but does show up in CS5 and ACR, and on this site when viewed in Firefox. Exposure and lens don't matter, as I have seen this in several different files. I don't remember this being a problem before, and haven't made any changes to my system recently.
The attached picture is a straight conversion in DPP, with nothing done during conversion. I resized in CS5. The posterization is visible in CS5 even in the shrunk version, showing up cyanish bands across the sky at top of the rocks. The rocks are also more contrasty in CS5. Is this visible or not visible to others here? Any ideas on why it only shows up in certain programs? I assume it has something to do with color management. I don't use any special profiles with my monitor, but the prints turn out fine. Thank you.
However, ACR is still showing the posterization. I reset the defaults, and deleted the .xmp file. What else do I need to do?
EDIT: the posterization is still evident in the repost, though it looks fine in CS5 now. What gives?
thank you.
Most likely there is a color in your image that is being converted to the cyan that you are seeing. I suggest that you set ACR and your Preferences in Photo Shop to Adobe RGB 1998, Relative Colometric and Blackpoint Compensation. Don't use Monitor RGB at all because it typically has a narrow gamut, is specific to your monitor, and if your monitor is uncalibrated, color will be inaccurate.
Open the converted tiff image in Photo Shop. Go to Edit>Convert to Profile to see what the working color space is. If the working color space is anything other than Adobe RGB, convert the file to that color space. Next, duplicate the file and go to Image>Mode and be sure that 'RGB Color' and '8 bits/channel' are checked. Flatten the image, convert the profile to sRGB, resize and sharpen as needed. Now, go to File> Save for Web and Devices. Be sure that 'Embed Color Profile' is checked. Save the image.
If your preferences are correct and you've embeded the correct color profiles, the banding should be gone.
You might want to take a look at my post Photo Shop CS5 Peformance Tuning for more information.
I hope this helps,
--P