CMYK Notes
JPEG does NOT support CMYK by spec, some programs will create hackish ones that may work.
TIFF does support CMYK (but TIFF itself isn't really a standard)
PDF is a container, items inside it can be RGB, CMYK or some of each.
- So. Really, either test the items inside the PDF. Or get a TIFF. UGH. No wonder they always use TIFF.
Convert with ImageMagick:
- go to imagemagick folder - C:\Program Files\ImageMagick-6.8.9-Q16
- convert.exe c:\temp\test-2013-11.png -colorspace cmyk -compress lzw c:\temp\test-2013-11-out.tif
- note the -colorspace option
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MISC
Test Page: Nice big RGB circle on page 4. Will show limits of CMYK.
Nicer, bigger, graph of the CMYK and RGB gamuts:
CMYK and RGB gamuts are vastly different. Spot colors, generally possible in CMYK, are outside the gamut... can be anywhere... can be glitter!
"CMYK's weakest areas are bright saturated blues, which will always print like crap because the inks just cannot print those colors. You haven't told anyone exactly why your conversions look like crap, only that they do.'
How do I even see if the file has rich black or is in CMYK?
-- identify -verbose image.jpg | grep "Colorspace:"
- Adobe Reader Pro can do this apparently.
- Import TIFF into blank Scribus document. Right click. Clearly shows CMYK under Info-Colorspace
-- In print preview of Scribus, you can turn on and off individual CMYK layers. This is clearly working.
-- Printed. Looks OK. But I am not at all sure it hasn't been converted to RGB and back!
How do I print to the Konica a CMYK TIFF (and know it's not been converted?)
-
-- Scribus doesn't support a LOT of SVG.
-- Maybe don't use SVG in Scribus? Use an EPS or PNG? "You don't need to learn Scribus, simple export an .eps file of your work. In Scribus import the document. In Scribus, Window menu, select Preflight Verifier. If there are any pre-press problems with the document it will tell you what needs fixing." - http://gimpchat.com/viewtopic.php?f=15&t=6430
- Run it through Photoshop Elements?
- Will this work: http://www.rgb2cmyk.org/ - exports to TIFF. 8MB limit. A shade small for our PNG files. JPG should fit OK.
-- It claims to have made a file. How do I test?!
-- Import TIFF into Scribus. Right click. Clearly shows CMYK under Info-Colorspace
- Ghostscript - probably what's running on rgb2cmyk.org
Earlier notes:
"True Black" is sort of the K in CYMK.
"Rich Black" is K, PLUS CYM underneath. It matters in print-presses which apply colors with plates using ink for each. It doesn't matter in laser printers (the driver would make them the same... I think).
http://en.wikipedia.org/wiki/Rich_black
"There are many different possible ink combinations - the most common "rich black" contains percentages of all 4 inks: 63C, 52M, 51Y 100K. This particular variant owes it's popularity to Adobe Photoshop - when an RGB file is converted to CMYK, areas that are absolute RGB black (R0, G0, B0) will wind up with this combination, unless certain default settings have been changed."
http://www.printernational.org/rich-black-plain-black.php
Original page down...
Import Inkscape vector into Scribus...
"You can see the two ‘FromSVG’ colors. It seems that the artwork includes a color that I didn’t really intend it to (perhaps a hairline outline that I missed), but that’s not important. I edited the black color swatch using the Edit button, which opens the color editor. It’s also worth noting that RGB swatches have the RGB vertical bar icons next to them, whereas CMYK swatches have the CMYK checkerboard icon."
"In the color swatch editor, I changed the Color model to CMYK. That was it, because Scribus automatically converted RGB black to 100% black. I saved the swatch and closed the color palette."
"Next I needed to get rid of the red outline. When you import a SVG file into Scribus, the individual parts of the artwork are all grouped into a single object. To manipulate individual objects, you first need to ungroup them. That’s exactly what I did with a couple of pushes on Ctrl+Shift+G."
"Using the Color tab in the properties palette, I removed all the offending outlines. Finally, I exported the PDF. To do that, I simply clicked on the PDF icon."
"Once the export dialog is opened, I went over to the Color tab and selected Printer from the Output intended for drop-down in the General section. This makes sure that the resulting PDF is a CMYK file. There are other settings there, and it’s a good idea to go through them at least once to get some ideas of the options you have."
tags: cmyk, cymk, rgb
