Photoshop my room
December 5, 2017 8:04 AM   Subscribe

I want to do a personalized recreation of Carnovsky's RGB murals for a wall in our bedroom (yes, it will be insane, yes it will be awesome). I have found a few companies that make custom mural wallpaper, I have a bunch of images I want to use for the design, I have basic (basic) photoshop skills. I completely lack the ability to understand how to make this work technically (what colors to use, how many layers I will need). Can anyone with RGB-CMYK knowledge and design understanding walk me through this please? The idea is when you shine different color lights on the wall, different images show through. Thank you!
posted by andreapandrea to Media & Arts (5 answers total) 4 users marked this as a favorite
These murals (or ones incredibly similar to them) are featured at the NYC Natural History Museum's newest exhibit. You could try reaching out to them, or visiting the exhibit (if you're nearby) and speaking with the science folk who are docenting it.
posted by Mchelly at 8:46 AM on December 5, 2017

Based on how the images look, they appear to be literally CMY (no K) while the lights are RGB. It is not a 1-1 relationship between layers and lights.
posted by O9scar at 10:12 AM on December 5, 2017

Roughly, if you have a blue image and use blue lighting, the blue will fade out. I think you are going to need trial and error. Use photoshop to make color separations then re-apply/combine them off setting each layer. Print on plain paper, shine different lights, see how you like it. You can use the rasterbator to make large images.
posted by theora55 at 10:49 AM on December 5, 2017

Best answer: First, you need to convert your images to black and white, 'posterizing' with 2 levels will probably give you the best results if they are not illustrations that lend themselves to being depicted as a single color.

Decide which images will be visible together, and group them into three layers: cyan (#00fff hex, or RGB value 0/255/255), magenta (#ff00ff or 255/0/255) and yellow (#ffff00 or 255/255/0). Then replace the color of your images on each layer with that color, making sure your hex code or RGB value for the color is set so it prints correctly. Do some test prints to make sure it looks good to you, and you should be good to go.
posted by ananci at 10:59 AM on December 5, 2017

Best answer: Step one is image prep—you need to enlarge each image to the size it will print at without turning it into a blurry, pixelated mess. If you're working with very high resolution scans of woodcut illustrations this will be pretty easy but the lower the image quality the more care and experimentation it may take to find a method you like. Your best bet is probably a chunky halftone. Open your first image in PS and use Image>Image Size to set the size you want that image to be in Inches. Now select Image>Image Mode>Greyscale and then Image>Image Mode>Bitmap, at 300 pixels per inch. This is when you want to try out the various halftone types to see what halftone shape fits the look you want—I like 'round' and 'line' a low number for the 'frequency is what you want here, I think a frequency of "1" (the lowest allowed number, biggest sized chunks) looks good but you can experiment around. On this step you should be setting your angles as follows: Images going Magenta at 45, images going Cyan at 75, and images going Yellow at 15 to minimize interference. Once you've got the hang of the process and know what settings you want to use you can repeat this on all of your images.

If you have Illustrator or InDesign I would do the next steps in one of those. Take all of your processed images and save them as Tiffs and then File>Place them in a CMYK Illustrator/Indesign Doc sized to your wallpaper template size. Select all the images of a given color and then set the color of each block of images to Cyan, Magenta or Yellow. Then you can play around with placement and export out as a PDF or Tiff.

If you only have Photoshop you will need to set each layer's color individually. Make a CMYK document the size of your final output, same 300ppi resolution as your bitmaps. Copy/paste in your image and set the Blending for the layer to "Multiply". Then double click the layer to set a layer style for that layer. Use "Color Overlay" with the Blend Mode set to "Hard Mix" and the color set to 100 for C, M, or Y with all the rest set to 0. Repeat for all of your images. When you have everything how you want export as a CMYK Tiff (not a JPG!)

Some experimentation is probably needed so try setting up a simple one that you can print at home or print a small section of your wall sized image to test first. I recommend that you do not use RGB/hex values. If you have Photoshop you should be keeping everything in CMYK color space the whole time.

Let me know if you need a more detailed explanation of any of the steps. Good luck!
posted by metaphorever at 11:08 AM on December 5, 2017 [2 favorites]

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