ProPhoto Colour Cast

Jayst84

Jayst84

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James
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Hi all,

Wondering if anyone here has come across this problem?

I've just moved to a new PC (from an ageing iMac) and I'm getting a colour cast on my black and white images now in Lightroom and Photoshop. (And possibly on colour images, it's fairly subtle and I haven't checked any colour files in detail).

It appears to be something to do with the ProPhoto colour space. Any black and white image in LR has a slight purplish cast to it, visible to the eye, and confirmed with the colour sampler i.e. the RGB values aren't equal. It's the same if I export to edit in PS, and if I export a colour image from LR to PS and then convert to mono in PS.

It corrects itself if I convert the colour profile to aRGB or sRGB in PS, I then get a nice neutral black and white file.

The problem remains on export to JPEG also. So, anything exported from LR (ProPhoto) to an sRGB JPEG, retains the colour cast. Converted to another profile in PS and then exported, it is neutral.

Anybody know how to fix this?

Thanks!
James
 
I used to get this with ProPhoto. Never really did b&w but my colour photos had a green tint to them. Reverting back to sRGB sorted it out. PS was set to save the file in ProPhoto as default and looked fine up until that point. Once it was back in Lr it looked green.

Not really any help to you mate I guess. :LOL:
 
Pro Photo RGB and AdobeRGB have different white points, D50 and D65. So you need to calibrate the screen and room lighting for each.
 
st599 said:
Pro Photo RGB and AdobeRGB have different white points, D50 and D65. So you need to calibrate the screen and room lighting for each.
Click to expand...

The screen calibration is fine. It's an issue in the software because the RGB values are different, and not neutral as they should be in a black and white image.

Room lighting is room lighting. You don't need to set it differently depending on what colourspace you're working in. Just as a calibrated screen is a calibrated screen, imagine if you had to re-calibrate every time you wanted to look at an image that was tagged with a different colour profile, that'd be mad.
 
Sorry, the room lighting is critical to screen viewing. If you don't match the screen white point, you perceive a colour shift due to the chromatic adaptation of the visual system. (See Langford, M., 'Advanced Photography' p221)

ProPhoto and AdobeRGB have different white point encodings, so to view it properly need a different calibration. Otherwise your colour management system will be applying a transform to display it, at which points all bets are off about accuracy.
 
st599 said:
Sorry, the room lighting is critical to screen viewing. If you don't match the screen white point, you perceive a colour shift due to the chromatic adaptation of the visual system. (See Langford, M., 'Advanced Photography' p221)

ProPhoto and AdobeRGB have different white point encodings, so to view it properly need a different calibration. Otherwise your colour management system will be applying a transform to display it, at which points all bets are off about accuracy.
Click to expand...

Consistent room lighting can be important, yeah. Critical to the point of blocking out all light and only using precisely calibrated bulbs? Probably depends how exacting you are. Like those who paint their walls 18% grey, and only process wearing grey hoodies. Either way, it's not going to change the RGB values of a file, so isn't the issue here.
 
No, all constant values will not appear white under incorrect lighting or a screen with the wrong white point so the colour management will change the output to match the screen.
 
OK, it appears I may be an idiot. I had a colour film emulation on the files as part of my batch processing. I'd then just converted that to black & white in LR, So it appears the underlying 'fake' camera profile was introducing the colour. Not sure what exactly, as if I turn off all the adjustments, and reset the profile to adobe standard, or any of the canon profiles, it still has a colour cast.

Anyway, doing a straight black and white from scratch works fine. Could've sworn I'd tried that (it's the obvious thing to do right!).

Sorry folks, as you were...
 
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