(Still working on “Trajectory”, but following several threads of other work.)
Just a short share for those printing artwork as photos and as images on garments.
We see thousands of colors, most of which our technology cannot duplicate. RGB is what you see on the screen and is a reduced palette. CMYK is what you use when screen printing and DTG (Direct To Garment) printing for a t-shirt and the palette is just part of the RGB, another reduction. This is explained on lots of sites in more detail. For you convenience, here is one from Printelf.com: RGB to CMYK youtube video
Photos: I tried Fedex Kinkos and was disappointed with the results. They printed an image of a painting on 2 different copiers and they were really different from each other. It appears they had different color “profiles” from one another. This inconsistency led me to find another printer. The one I currently use requires an RBG file with 300 dpi and the image must fit withing the space allowed – they will not resize it. I have no idea if they change it to CMYK or not, but my advice is to find a local place, follow their guidelines,do a few small (inexpensive) test prints and see.
DTG: Many of the printing companies will provide advice to get a printed chart or garment from them with color swatches. That allows you to pick a color that is printed, then enter the numeric match in CMYK in Photoshop. That can work well, though you may be out a few dollars just to get the garments. You pick the region, then “fill” with the print match.
Suppose you have a solid black triangle printed on a t-shirt. Using their advice, you can actually get a “richer” black than you would using 100% K (black), 0% for C (cyan), M (magenta), and Y (yellow). Great! Similarly, printing a red can match your work pretty well to printed garment – if it’s solid, like a triangle.
Here are the problems that I don’t see a solution for. 1) Suppose that solid triangle is hot pink or some other color outside CMYK printing capability? You are left with a lackluster pink. 2) I use gradations of color and intersections of color. Their solution requires a “fill”. That is impossible with many of my colored pencil drawings and paintings. 3) Colored pencil or white conte work created on a black background? Impossible almost. To print on a black t-shirt, I removed the black by various PS techniques, so the garment color could replace the black in the image. The black in my original was so integrated that I either couldn’t remove it entirely or being more aggressive, removed adjacent coloring. No real solution here for #3. You can print black on a black garment – the blacks will not match, but not always a problem.
For #1 and #2, I adjust my colors in the CMYK file using the histogram in Photoshop, then save it to a PNG file for the company that I use. If there is no background, you STILL may get a residue if the background opacity is anything other than 0%. Then I pay for a test garment to be sent to me. Bit of a scam – I end up being my own best customer. Sometimes the printed image is good/adequate, sometimes not. Once in a while it is not a match, but actually is pretty interesting “interpretation” of your work. Good luck and share your experiences printing, please.