100% k in photoshop?

wicky

wicky

play thing
I've got a load of B&W logo's supplied as grayscale tif images. The printer has come back to me saying that the PDF that I gave him has different colours in the black, and so they are producing 8 (?) colour seperations.

All the images are in a greyscale profile, so what's happening?

I've changed the logo's to CMYK, and transferred everything to a black spot channel, then deleted the contents of the other channels. All seems well, with the eyedropper tool only picking up black where it should be black.

When I get rid of the redundant channels (so that I'm not producing CMYK, but single colour), the eyedropper tool is picking up colours in the black again.

How do I get a greyscale image to just be black and a tint of black, so that it does not produce CMYK channels in the Quark output?

ta
 
8 separations - that's a fancy print job you've got there!

Sounds like you may have a problem with your output settings rather than the images. You should go through your output options with your printer to find out what's wrong. No reason to have any problems with grayscale TIFFs - although I don't use any compression - apparently some RIPs [used to] have problems with LZW compression (gawd knows what to make of this new fangled JPEG compression in TIFFs). I reckon your PDF options might be converting the grayscale to colour - but that would only account for a regular 4 colour process job unless something is really mangled up - seems most likely that you've got some spot colours defined in the quark document...
 
'k... but why does the eyedropper tool register CMYK colours when the image is greyscale?

The image was C=0 M=0 Y=0 K=99, when saved as CMYK. Once changed to Greyscale, the values have changed to C=71 M=66 Y=64 K=73. What is happening, and why isn't it just registering black?

Ta
 
Hi wicky - do me a favour and check your info palette options - are they set to actual colour - or CMYK. If set to CMYK (or any other colour space) the readout you are getting is an on-the-fly colour conversion based on your Colour Settings. This does not mean that your image is necessarily CMYK.

If you have CMYK colour set as the readout in the Info Palette - the reason for the high numbers will be that Photoshop would convert your black image into a "rich black" CMYK mix to approximate an on screen black - ie the darkest possible black allowed by the CMYK conversion options you have set in your Colour Settings. [I'm talking from the perspective of PS7 - but the principle would be the same on another version - although Colour Settings may not be under the Photoshop menu.]

If you ever need to convert an RGB or greyscale image to CMYK - and keep blacks or greys exclusively in the black channel you now (in PS7 at least) need to create a custom setting, with a custom CMYK working space, within your Colour Settings. Base it on the closest available preset but change Black Generation to Maximum. Save this setting to the /Library/Application Support/Adobe/Color/Settings/ folder. Remeber to only use this setting when you need to though - as it would f**k up regular RGB to CMYK conversions.

Anyway - guess I'm going on a bit....
Check out Photoshop Help and maybe CreativePro.com for more.
 
You must log in or register to reply here.
Back
Top