The working difference with RGB vs CMYK modes in Photoshop.

When I started working on my graphic novel called "reMIND", I read that printers needed CMYK files so I decided to create all my Photoshop pages in CMYK only. I worked in this mode for years thinking it was similar to RGB but just printer safe. I Ignored the fact that some of the filters didn't work because I rarely used them. A few years in, I was trying to adjust my pencil lines to be solid black with Levels but could only get a light gray line for whatever reason even though there was solid black elsewhere on my canvas. There was no real reason for this and it drove me nuts when it happened. I mean, printers can print black so what's the problem here, CMYK? 
 
I switched over some of the problematic files to RGB and easily got the lines to turn black. Then I switched it back to CMYK and it finally looked right. I started running into other problems adjusting the Hue/Saturation of specific colors in my CMYK files. Sometimes I'd try to adjust the saturation and my textures would disappear. Sometimes when adjusting a color, I couldn't even get it into the right hue. Or when I'd try to turn the brightness down to black it would turn lighter. I worked around these problems before but now I was starting to get frustrated. I switched my file to RGB again and suddenly after years of denial my eyes were opened. 
 
For some time now I've been itching to do an experiment to see what the true difference is between the two modes. So I recorded myself adjusting an identical file in RGB and CMYK, applying the same adjustments to each. I brought the footage into AfterEffects and time remapped it, lining it up as close as I could. The end result is pretty interesting to me after pulling my hair out for years over why I couldn't get my stupid colors to look right. I hope it helps you decide which mode to work in and why. When I first wrote my list of things to know before starting a graphic novel, I told everyone they should work in CMYK. I now think the opposite is true and updated the list to reflect my new opinion.
 
My apologies for the funky sound mix. I accidentally said CMYK instead of CMYK for the whole video and had to splice in the corrections later. I know a few are still in there somewhere but who cares. Hope you enjoy the video. Right click it to watch on YouTube for the best resolution or full screen.

Notice how the textures turn into flat colors in CMYK when they are adjusted with an overlay. The other thing that drove be crazy was towards the end of the video, turning plain texture to white and still having dark spots or turning it to black and having uneven blacks. It's not as clear in the compressed video but the CMYK file has blacks and dark blacks for some reason. I mainly wanted to show the basic differences with the modes and why it's just easier to use RGB and convert  your flattened file to CMYK when you are finished. Always save your master file with all the layers in RGB though.

Hope this helps!

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