How to Convert RGB to CMYK for Press (...the simple way.)
getting your image files printed to card stock.
Let's start off by saying we've messed up a few postcards of our own before finally getting to this simple solution. So if you're in the same camp read on. If you're a graphic design wiz kid this will probably be a really boring read.
The main issue with printing your digital image at one of those online postcard places is that they require you to give them CMYK versions of everything and your digital files are RGB. Combine that with the fact that screens don't accurately display CMYK anyway and it's confusion city.
If you have ever had muddy results from doing a quick conversion to CMYK then here's a quick and easy solution (provided you have access to Photoshop.)
Always try to work in layers so you can select individual images and backgrounds to adjust.
- Save a copy of your file for the conversion and leave both open. (we add 'CMYK' to the name of the converted one.)
- Convert that file to CMYK: ( Image>Mode>CMYK)
- Now you can view both RGB and CMYK versions side by side.
- If you have a pure black area the build should be C:50, M:50, Y:50, K:100. (Total 250) This is a perfect pure black build for print, anything above this will begin to bleed. (Select the foreground box on the tool palate to build this black (put values after CMYK) and then fill the area with the paint can tool.)
- Take the eyedropper tool and view the CMYK totals of your black and dark areas in images. The goal is to keep the total of all CMYK values below 240-260.
- To adjust these totals down so they don't come out muddy ('gain'); select the layer in question and then go to 'Selective Color' (Image> Adjustments>Selective Color)
- In the 'Selective Color' control window select "Blacks" from the drop down menu at the top; then reduce the C, M and Y sliders down 10-20% but leave the Black (K) one untouched.
- Go back to the image and total the CMYK values again using the eyedropper and repeat this step with all of your images until your totals are acceptable.
- Take a steely eyed look at the RGB version next to your newly adjusted CMYK version. Unfortunately they will never look alike but if you see colors that need some adjusting there are a few more simple tricks that we've listed below. Don't over do it here, reducing the 'gain' (blacks) described above is really the most important step of all.
- To reduce a specific color simply go to Selective Color again, choose the color in question from the drop down menu and then move the corresponding slider in the opposite direction and take another look. Yes, this is completely subjective and we highly recommend doing as little of this sort of thing as possible.
- Shifting the reds to a more favorable skin tone: Select layer, (Image> Adjustments>Hue/Saturation) Now select Reds from the drop down menu and move the Hue up 3-6, The Saturation down 2-5 and adjust the the brightness slider till the preview looks similar to the 'before'. Done. (You may want to 'undo' this step on the lips if affected by using the history brush.) Again this is a subjective tool.
- We hope this article helps you print a perfect postcard!
Big thanks to Kelley King for her help in coming up with a tangible solution!