Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: Michael Z on April 13, 2015, 06:03:40 am
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I've started delving into black and white digital photography and I have this issue that seems to be bothering me.
I convert my photos to black and white either using Lightroom or Capture One Pro and I make the RAW adjustments (i.e. use the colour mixers, contrast etc).
I then export the image with the changes to Photoshop to do some final changes. However, whenever I open the image in Photoshop, I notice the black and white image has gained
a very slight green tint to it. As in the whites don't look white, they look greenish white. If I compare the image to the black and white image from Capture One Pro or Lightroom, it looks like a true greyscale image.
So I started messing around in Photoshops colour settings.
If I convert the image to a greyscale (which removes all the colour channels) with a gamma of 2.2, the green tint disappears leaving me with a nice greyscale image.
If I keep it in an RGB colour space (I've tried DCam, Adobe RGB, sRGB, ProPhoto) the green tint comes back.
I've tried changing the intent, different engine, everything that the colour settings allow me to. It's whenever I work in a colour space, the black and white has a green tint to it in Photoshop. Convert it to greyscale and it's gone.
Is this normal for Photoshop? Even Windows Photo Viewer doesn't display the green tint.
I've calibrated my monitor with i1 Display Profiler and use a Wide Gamut monitor.
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Hi,
This looks like a color management issue. I would need some additional information to be able to help:
Could you post a screen shot of the Photoshop color settings? (Edit -> Color Settings)
Also, if you sample the color in any of those "greenish" areas, do you get R=G=B?
If possible, post an image with the green issue.
Regards
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If you are not using the latest Photoshop CC 2014, it may have a BUG...
See http://www.modelmayhem.com/forums/post/921316
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"Messing about" with Photoshop's color settings is, well, never a good idea. Don't change anything from defaults unless you know what you're doing! You can quickly find yourself in an unholy mess with a long way back.
Above all, never set color management policies to anything other than the default "preserve embedded profiles". Changing this, again without knowing what you're doing, is guaranteed to blow up in your face.
But if everything here is kosher, I'd suspect the display profile. Yes, everything ends up in the same display profile whatever the source profile is. But the actual conversion is different in each case, so a problem could show up differently with different document profiles. It could also show up differently in different applications.
Recalibrate, and make sure you have i1 Profiler set to make v2 matrix profiles. This is the safe choice - v4 and/or LUT can sometimes cause problems.
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When one of my colleagues sends be b&w for printing, he always seems to simply kill the saturation and the images tend to vary slightly in tone when I've printed them. Desaturation simply doesn't keep an image neutral.
So what I do with his work is to use a black and white adjustment layer on top of adjustment layers to keep make the image consistently neutral. If you have a favorite tone such as sepia, you can use the same black and white adjustment layer to "tone" your image, just like in the darkroom.
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You say it has a greenish tint but is this on the monitor or is it on a print?
Keeping the image in the RGB colour space means the colour information is still there but desaturated. Converting to greyscale discards it.
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Keeping the image in the RGB colour space means the colour information is still there but desaturated. Converting to greyscale discards it.
True, but that’s no guarantee the output will be neutral, grayscale (to a color printer) or R=G=B.
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Thanks for all the tips.
Here's a more visual presentation of the problem I'm having.
These are screenshots of what I was seeing in photoshop.
You'll notice that the RGB all remain the same number, however if you take a look in the shadows (marked by colour picker '1') that there is a strange greenish tint and what I believe is banding or posterization?
This image was converted to black and white straight from Capture One Pro 8 with only slight adjustments made to contrast etc. Capture One Pro 8 doesn't show this problem, it looks like a normal greyscale image.
Image 1 is a screenshot with the green tint - it's in adobe RGB colour space.
Image 2 is a screenshot without the green tint - it was converted to greyscale with a gamma of 2.2.
Image 3 is a screenshot with the green tint and Photoshop's colour settings.
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The screen captures all appear green to me, the numbers define neutrals so I suspect you’ve got a display calibration issue.
Be useful to have ALL info palette readouts in RGB (convert the grayscale back).
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The second greyscale image is exactly the same as the first one but converted to a greyscale with a gamma 2.2 with all colour channels discarded.
When you say converting it back from greyscale are you asking back to black and white with the colour channels or as a coloured image?
I'm going to try and recalibrate my monitor. I mainly view my work through print so I want my monitor to best match the prints it can.
These are my i1Profiler settings:
Display Settings:
Wide Gamut CCFL
White point: CIE Illuminant D50
Luminance: 80
Target contrast ratio: 150
Flare correct: Off
Ambient Light Smart Control: off
Default Profile Settings
Chromatic adaptation: Bradford (default)
ICC Profile Version: Version 2
Tone Response Curve: Standard (default)
Gamma: 2.20
Profile Type: Table based.
Default Patch Set
Default Patches 462
Patch set size: Large
Patches from spot colours: 0
Patches from Image: 0
Are there any problems with these settings?
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The second greyscale image is exactly the same as the first one but converted to a greyscale with a gamma 2.2 with all colour channels discarded.
When you say converting it back from greyscale are you asking back to black and white with the colour channels or as a coloured image?
Yes, then show the RGB values like the other (and do you see more of a green cast?).
I'm going to try and recalibrate my monitor. I mainly view my work through print so I want my monitor to best match the prints it can.
Are they too greenish?
Are there any problems with these settings?
Just seeing a set of calibration targets doesn’t tell us anything. The settings that produce a visual match to the print is what we shoot for. A green cast on the display would indicate an issue with your white balance but the question is, does the software provide the opposite color axis adjustment from yellow to blue ( that being magenta/green)?
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I hope this is what you're looking for.
When I convert it back from greyscale to colour RGB the green tint still persists. It doesn't appear to get stronger or weaker. It just reverts back to the green tint it was prior to a full grayscale conversion.
I find it strange how it's only Photoshop that shows the green tint. DxO OpticsPro 10, Capture One Pro 8 and Windows Photo Viewer doesn't show it. So I'm thinking it's not a monitor calibration profile issue but a Photoshop issue?
Edit: I've also added an iProfile midtone black and white image. To me it doesn't look greenish. Does it look greenish to your trained eye?
iProfiler was able to achieve the following results:
White Point
CCT: 4952K (target D50)
Target: x: 0.346, y: 0.358 Achieved: x: 0.347, y: 0.358
Luminance: Target: 80 cd/m^2 Achieved: 81 cd/m^2
Contrast ratio: Target: 150 Achieved: 158:1
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I hope this is what you're looking for.
When I convert it back from greyscale to colour RGB the green tint still persists. It doesn't appear to get stronger or weaker. It just reverts back to the green tint it was prior to a full grayscale conversion.
Well the new numbers don’t represent neutral values, odd. You converted from Grayscale back to what Working Space? And what’s up with that adjustment layer? What’s up with that added channel?
Can you crop a small area of the original file that shows the green cast and upload so we can examine on our end?
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It is possibly an issue with the monitor profile.
In Photoshop you cannot change the monitor profile since it is set up in the operating system. Other applications such as DXO OP let you change the monitor profile.
To check the profile being used by photoshop, go to Edit -> Color settings and click on the list of RGB profiles and search for the one that starts with "Monitor RGB - ..." Make sure it is the correct one and the same used in your other color managed applications. NOTE - DO NOT SELECT THIS PROFILE AS THE WORKING RGB, the safest option is to click "cancel" in the color settings dialogue.
One quick test for the monitor profile is to download the test image "PDI Target-Whacked RGB" from this site: http://www.gballard.net/psd/colorlooksbad.html (http://www.gballard.net/psd/colorlooksbad.html)
If the image does not look fine with the grays neutral, then you monitor profile is bad
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It is possibly an issue with the monitor profile.
I agree with your suspicions, that’s why it would be useful to get an actual image.
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Thanks for the help, much appreciated.
I turned off "Compensate for Scene-referred Profiles" in the colour settings. Initially it didn't do anything, the green tint remained.
I then restarted Photoshop with the setting still off, and I noticed the green tint was gone. So I turned it back on - the green tint remained gone, restarted Photoshop and the green tint was still gone.
Also, the coloured redish and greenish posterization that would band across my black and white images when in a RGB is now gone too.
Perhaps this is a bug in Photoshop? I'm not sure what could have initially caused it.
Now that the green tint is gone, I can't really provide you with an image that shows it.
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Photoshop loads the display profile at startup. Any change requires a relaunch of the application to take effect (but no reboot).
The calibration software puts up the "scene-referred" flag - erroneously in this case. So this is an i1Profiler bug, not a Photoshop bug. But turning it off in color settings bypasses the problem. This was a quite frequent problem some years ago, often coming up on the Adobe Photoshop forum - so it's surprising it's still there.
In addition, setting i1Profiler to "table based" (LUT) profiles is a potential problem. Some applications, under some circumstances, don't handle that well. For instance, I see clipped blacks in Firefox with LUT profiles from Colornavigator, while matrix profiles do not show this. Photoshop/Lightroom do not have any problems though, at least not here. But LUT profiles, generally, are quite heavy and complex compared to matrix profiles.
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It looks like I am having the same / similar issue.
I have noticed that in greyscale images, in proPhoto rgb, 16bit or 8bit, there is a greenish tint in the darkest tones (see screen capture).
Unlike the original poster, I can not solve this....
Here are some facts.
- This is only visible in Photoshop (CC 2014), in proPhoto rgb.
- It is visible when using custom monitor profile (created with colormunki display).
- It is visible when using srgb default monitor profile that comes with Windows.
It is not visible in any other app.
- Not in Lightroom.
- Not in Imageglass photo viewer.
- Not in Nik Software Silver Efex 2.
- Not in Google Chrome.
- Not in Photoshop when using Adobe rgb, or srg.
The image was created by:
- Creating new image in prophoto rgb
- Adding gradient.
- Desaturating image
- posterizing image (60 levels)
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The screen captures all appear green to me...
For what it is worth, I can clearly see the difference between the screen captures (and the greet tint):
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Looks like I found a solution here http://www.modelmayhem.com/forums/post/921316 (http://www.modelmayhem.com/forums/post/921316)
The culprit seems to be GPU acceleration. This bug has been reported but....
Anyway, changing mode in GPU acceleration to Basic, fixed the color cast and I now seem to have a perfectly neutral greyscale image.
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This is a new one. I've seen banding and clipping, but not a general color cast.
The ProPhoto/OpenGL bug in Photoshop has been well known for a long time, even to PS engineering staff. It was first reported on the Adobe Photoshop forum several years ago (IIRC CS5 was then the current version). At the time they said they'd "look into" it, and since then - total silence and the bug is still there.
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I've started delving into black and white digital photography ...
If black and white is your primary focus, you might consider one of the dedicated black and white inksets. Jon Cone has a turnkey system, and MIS (inksupply.com) sells the inputs I use. Using an inkset designed for high gamut color to do black and white printing is obviously not the best way to go.
Paul
www.PaulRoark.com
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If black and white is your primary focus, you might consider one of the dedicated black and white inksets. Jon Cone has a turnkey system, and MIS (inksupply.com) sells the inputs I use. Using an inkset designed for high gamut color to do black and white printing is obviously not the best way to go.
Paul
www.PaulRoark.com
Paul, Michael Z hasn't mentioned printing yet ...