cmyk vs rgb : LUSENET : PosterShop Talk : One Thread

I was playing around the other day and all my images that I take using our DCS460 Camera produce RGB images, but I converted on (just for fun) to cmyk. When the poster printed the cmyk image out, it was sharper, had more detail and looked like a photograph. When I looked at the RGB image it was flat, not as sharp and looked bad.

Why would the CMYK image look so much better? Does Postershop have a built in coversion that isn't as good as me converting in Photoshop?


-- Anonymous, June 16, 1999


In general sending RGB images to CMYK output without a correct conversion is a bad idea. The best case is to use a profile that characterizes your Camera, and a profile that characterizes the printer together to get the best quality output. To better answer your question I need to know what sort of profile setup you are using in PosterShop (File->Profiles->Basic), and how you are getting the image to PosterShop. If you aren't correctly using profiles in PosterShop, you can get unsatisfactory results. Things can also get really tricky if you are placing the RGB images into an Application document that is output/converted to Postscript. This is because the Applicaiton may be converting the RGB to CMYK incorrectly before it gets to PosterShop. (Quark 4.0 for example). You may get better results by converting to CMYK before importing into the Application, before outputing to Postscript.

-- Anonymous, June 16, 1999

Quark 4 can be tamed if "printRGB" xtension is installed and active: then it will not convert rgb images (which it does not do well!) I found that PS 4.5 does an excellent job with rgb images in quark long as the rgb input profile selected matches the rgb color space of the rgb images print

-- Anonymous, October 14, 1999

I dont have "(File->Profiles->Basic)", but I have (File->Preferences- >Basic), which is set to "Use the default monitor profile". I'm using PosterShop 4.0.

Also when I was testing my printer, I am just talking an RGB image and coverting it into a tif file and printing that. Then I took the RGB image, coverted it to cmyk in photoshop, printed a small section on my printer, then set up a monitor balance in Photoshop, so that my output on the Poster Printer matches my monitor. So I am able to make my changes in Photoshop so it will look great on my Poster Printer. I set up the same calibration for my RGB images in Photoshop. But the cmyk look alive, compared to the RGB images.

In PosterShop doesn't using the "ICC Monitor Profile" not change the image, but just the viewing for me?

Thanks for your help,


-- Anonymous, June 17, 1999

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