A blog related to original AI artworks. I make AI artworks using coined words and emoji as prompts.

Trying CMYK Image Profile for Prioritizing Poster Printing

When printing from RGB images to posters, the colors can change significantly. While the images on this site are also intended for viewing on display screens, considering printing them as posters first, I thought it might be better to create the images using the CMYK color composition method, which is oriented towards printing, from the beginning. That’s why I experimented with it. In other words, I converted the original RGB images to CMYK (compatible) and then adjusted the contrast and brightness. By doing this, it should prevent significant color changes when printing.

RGB images are created by synthesizing R (red), G (green), and B (blue) to create a color image with light. In contrast, CMYK images are created by synthesizing C (cyan), M (magenta), Y (yellow), and K (black) to create a color image with color ink. There are colors that can be synthesized in RGB but cannot be expressed in CMYK. Therefore, it is said that when printing from RGB originals, the colors may become dull.

To avoid unexpected color shifts when printing, I experimented with creating images in CMYK in advance. Since the images generated by AI are in RGB, I will compare them to those converted to CMYK. The first image is RGB, and the second image is CMYK.

CMYK images display well in Safari, but it seems that the colors are incorrect in Chrome. The conversion to CMYK is done using the function ImageCms.buildTransform in Python. Since the image deteriorates significantly compared to RGB images, I manually optimized it. Although the color is worse than that of the RGB image, it has been greatly improved. This image is saved in RGB (edited on a Macintosh, it is converted to RGB), but the color should be within the range expressible in CMYK.

However, adjusting CMYK images is more difficult and time-consuming compared to RGB. Also, the colors are not optimal when viewed on a display screen. Although CMYK images look much better than RGB images on my printer, they still look quite good when printed at a printing shop. Therefore, although I edited in CMYK for a while around November last year, I switched back to editing in RGB.