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jonnysods
Jul 18, 2009, 09:18 AM
I know I'll probably get chased out of town for asking this.

I'm doing some work in PS (CS4), making some signs, the colour profile is in CMYK 16bit. Graphics look amazing, of course, because of the screen.

Now I'm ready to have them printed. I export a pdf and a .tif to get a sample of what they look like - and they look totally different!

I can't get my head around this - no matter what I try, I cannot get the colours to even look remotely close to the psd file I'm working on. It can't be the screen that makes them look different, because I'm using the same screen to work on!

To make myself even more of a noob on this forum, I changed the psd to 8bit CMYK mode, removed the embeded colour profile and saved it as a jpeg. That was the closest I could get to an accurate exported colour, but I dare not send that to a printer! I can't even imagine what it would look like when they are done with it!



Designer Dale
Jul 18, 2009, 03:45 PM
I need some clarification. Are you comparing screen views of different file formats or comparing screen views to a physical print of the same file?

Dale

Edit: If you are printing from a laser or inkjet, what model is it?

Kwill
Jul 20, 2009, 09:02 AM
You are doing at least three things that result in color shifting.


Switching from 16 bit to 8 bit
Converting from RGB to CMYK
Discarding the color profile

Ultimately, an exact color cannot cannot be guaranteed because your target gamma is much smaller than your original PSD file.

Suggestions:


Convert 16 bit to Smart Object before converting to 8 bit
Turn on CMYK proofing under View menu
Pay attention to "rendering intent" option in profile conversion dialog
Try using "Relative Colormetric (http://reactiveimaging.com/blog/20090325_convert.html)" or "Perceptual"
Include the color profile when saving flattened TIFF for print
Inquire which CMYK color profile is preferred by your printer
Some inkjet printers (8-12 inks) are able to print RGB files

Toppa G's
Jul 20, 2009, 09:25 AM
7. Some inkjet printers (8-12 inks) are able to print RGB files


I'm not sure what you mean here. Any inkjet printer can print RGB files, the printer just converts the color to CMYK.

Are you saying that an inkjet can produce true RGB? Since RGB is an additive, light-based color space, and all printers are based on subtractive, pigment-based CMYK (plus other colors for added vibrancy), this would be impossible...:confused:

Kwill
Jul 20, 2009, 03:00 PM
I'm not sure what you mean here.

Additive and subtractive color spaces can never coalesce. The point is that some inkjet printers, by virtue of their extended ink set, have a much wider gamut than CMYK. Therefore, they can produce better results from RGB images than CMYK.

The relevancy factors are whether such a printer is being used and whether the file is printed natively or in composition with other CMYK elements (i.e.: within InDesign). Since printed "signs" were mentioned by the op, I posited large-format printing via inkjet. If, however, the job is being printed offset, converting images to CMYK (with proper color settings for press gain) is warranted.

jonnysods
Jul 22, 2009, 09:49 AM
You are doing at least three things that result in color shifting.


Switching from 16 bit to 8 bit
Converting from RGB to CMYK
Discarding the color profile

Ultimately, an exact color cannot cannot be guaranteed because your target gamma is much smaller than your original PSD file.

Suggestions:


Convert 16 bit to Smart Object before converting to 8 bit
Turn on CMYK proofing under View menu
Pay attention to "rendering intent" option in profile conversion dialog
Try using "Relative Colormetric (http://reactiveimaging.com/blog/20090325_convert.html)" or "Perceptual"
Include the color profile when saving flattened TIFF for print
Inquire which CMYK color profile is preferred by your printer
Some inkjet printers (8-12 inks) are able to print RGB files


Thanks for the advice, I'll go through your suggestions and make sure that I'm lining up with what you say. This is not for me to print on an inkjet or laser, it's to send to an offset printer.

I was working in 16 bit CMYK mode in PS. When I flattened the file and converted to TIFF, the colour profile was embedded. The thing came out shockingly different though.

SnowX
Jul 22, 2009, 11:30 AM
If you want colour accuracy, then you need to work with PMS colours. Printing in CMYK on one press will yeild different results than printing on another press.

Kwill
Jul 22, 2009, 04:38 PM
I was working in 16 bit CMYK mode in PS.

Then the CMYK preview (step 2) won't make a difference. It's design to give users an idea of how an RGB image will look after conversion.