Differneces between CMYK vs RGB?

C
Posted By
Chaz
May 24, 2007
Views
234
Replies
2
Status
Closed
I am a casual user of Photoshop, and just recent noticed a difference between CMYK and RGB. I had to make a document smaller, and I noticed that changing the mode to RGB made the file size smaller, but left the resolution the same.

My question is probably very basic, but when should I use CMYK vs RGB? I do a lot of graphics for postcards and such.

Thanks in advanced!

Chaz

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TK
Toobi-Won Kenobi
May 24, 2007
"Xaos" wrote in message
I am a casual user of Photoshop, and just recent noticed a difference between CMYK and RGB. I had to make a document smaller, and I noticed that changing the mode to RGB made the file size smaller, but left the resolution the same.

My question is probably very basic, but when should I use CMYK vs RGB? I do a lot of graphics for postcards and such.

Thanks in advanced!
Chaz

Very simply, RGB is to monitors (display) as CMYK is to professional print processes (inks) (home printers labled as CMYK printers tend to be 4 colour RGB devices)

http://dx.sheridan.com/advisor/cmyk_color.html
http://www.turnkeycreations.com/tips_articles/imagemode.htm

Google for more

TWK
J
Jim
May 24, 2007
"Xaos" wrote in message
I am a casual user of Photoshop, and just recent noticed a difference between CMYK and RGB. I had to make a document smaller, and I noticed that changing the mode to RGB made the file size smaller, but left the resolution the same.

My question is probably very basic, but when should I use CMYK vs RGB? I do a lot of graphics for postcards and such.

Thanks in advanced!

Chaz
CMYK requires 4 bytes per pixel whereas RGB only requires 3. Thus, an image in CMYK mode should be
bigger than one in RGB mode.

I would keep all files on the computer in RGB mode. That saves space for starters. It is quite easy for PS to go from
RGB to CMYK; hence if your printer needs a CMYK file, you can get PS to convert during the printing process.
Inkjet printer drivers, however, expect the file to be in RGB format. Thus, if you send a CMYK file to an inkjet, the driver
first converts the file to RGB, and then converts it back to CMYK. It is almost a certainty that the end result will be
appreciably less than satisfactory.

Jim

MacBook Pro 16” Mockups 🔥

– in 4 materials (clay versions included)

– 12 scenes

– 48 MacBook Pro 16″ mockups

– 6000 x 4500 px

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