RGB to CMYK issue

[Grimfango]

Hi there!

im having an issue when I convert my photo to CMYK from RGB in photoshop.
The colour loss is huge, which is a shame but something I can adjust, however the other issue is that it's actually losing a lot of the detail with it. It's giving it the kind of effect you have when you whack the gamma up, almost like a solarised/white layer overlay effect or something. I've tried with the original and the flattened file but the results are similar.
The image may potentially be blown up to bus ad type size so it's really important the detail is still there.

Is there any cheat fix to this or perhaps something I'm missing?

Any help would be hugely appreciated!

 

[Tom Mann]

Hi back at you! Thanks for stopping in with your question.

One certainly will lose colors when going from almost any RGB space to almost any CMYK profile, but one should never lose detail. The number of pixels should always be exactly the same after conversion, and each pixel is converted entirely independently of all other pixels, so there's no possibility of softening or anything like that.

What I would suggest is that you post or send us two PSD files of an image that shows this problem. One is before you do the conversion, the other is after.

A warning: Posting PSDs on this forum sometimes gives people problems, so here are a couple of suggestions:

a) The image can (and should) be small -- say 650 pixels on the long dimension and flattened down to one layer. Any larger is not necessary, and it uses up data quotas for participants with metered / slow internet connections.

b) The forum uploading software doesn't recognize PSD files, so zip them together and post it the same way as you would post a normal JPG as an attachment to a post. At some point, you'll see a big question mark that indicates that it doesn't know how to display the zip file, but just ignore it and forge ahead.

If you don't see the zip file as an attachment to the post, let us know. I think someone actually did a video of how to post PSDs here.

Or ... if you don't feel like going through the above process, just put the zip file in WeTransfer, Dropbox, YouSendIt, or one of the similar file transfer services (not Google's, please), post the link, and we'll pick it up from there.

Don't worry, we'll get to the bottom of this.

Cheers,

Tom M

 

[Grimfango]

Hi back at you! Thanks for stopping in with your question.One certainly will lose colors when going from almost any RGB space to almost any CMYK profile, but one should never lose detail. The number of pixels should always be exactly the same after conversion, and each pixel is converted entirely independently of all other pixels, so there's no possibility of softening or anything like that.What I would suggest is that you post or send us two PSD files of an image that shows this problem. One is before you do the conversion, the other is after.A warning: Posting PSDs on this forum sometimes gives people problems, so here are a couple of suggestions:a) The image can (and should) be small -- say 650 pixels on the long dimension and flattened down to one layer. Any larger is not necessary, and it uses up data quotas for participants with metered / slow internet connections.b) The forum uploading software doesn't recognize PSD files, so zip them together and post it the same way as you would post a normal JPG as an attachment to a post. At some point, you'll see a big question mark that indicates that it doesn't know how to display the zip file, but just ignore it and forge ahead.If you don't see the zip file as an attachment to the post, let us know. I think someone actually did a video of how to post PSDs here. Or ... if you don't feel like going through the above process, just put the zip file in WeTransfer, Dropbox, YouSendIt, or one of the similar file transfer services (not Google's, please), post the link, and we'll pick it up from there. Don't worry, we'll get to the bottom of this.Cheers,Tom M

Thanks for your reply! I've attached the file (hopefully!) for you to see!

 

[thebestcpu]

Hi Grimfango

I put he sRGB image on the left with Soft Proofing turned on to the target CMYK profile and put your final image on the right and saw no difference in sharpness so do not see the issue you mention (other than the much smaller color gamut of CMYK). You can have a perceived loss of sharpness because of a reduced gamma and change in the black point or adjacent colors being a little more dull yet the edges look just as sharp to me:

 

[Grimfango]

Hi Grimfango

I put he sRGB image on the left with Soft Proofing turned on to the target CMYK profile and put your final image on the right and saw no difference in sharpness so do not see the issue you mention (other than the much smaller color gamut of CMYK). You can have a perceived loss of sharpness because of a reduced gamma and change in the black point or adjacent colors being a little more dull yet the edges look just as sharp to me:

View attachment 55013

Hi there,

Yes you're right, seeing it like that It doesn't appear to have lost detail. Perhaps it's the things you mention - how can I go about fixing those so it doesn't have that effect?

 

[Tom Mann]

A question: When u saw the solarized look, what software were u using to view the image?

 

[Grimfango]

A question: When u saw the solarized look, what software were u using to view the image?

Photoshop. Haven't taken it into another program yet as I noticed the solarised effect as soon as I converted it.

 

[Tom Mann]

Ahh. Good. My thought was that u might have been viewing it in a non color managed program.

 

[thebestcpu]

Hi there,

Yes you're right, seeing it like that It doesn't appear to have lost detail. Perhaps it's the things you mention - how can I go about fixing those so it doesn't have that effect?

A few steps
- Acknowledge that your color space is not what you see on your monitor without soft proofing yet the target color space with its limitations.
- Increase the luminosity difference to the two colors. Half was lost going to CMYK
- Consider increasing the Hue separation. They are very close to each other
- Add some sharpening to the edges. Even having a tinge of white from the sharpening may be OK for this type of image.

Just some quick thoughts. Hope it helps

 

[Tom Mann]

I finally had a chance to get to a machine with PS on it and looked at your two PSD files. Including the expected color degradation, the "after" version looks exactly as I would expect -- no solarization, no white veiling flare, etc. So, I don't know what to say.

Tom M