CYMK Color Mode

[jamessk]

Hi All,
I am fairly new to Photoshop and color modes, hence why I'm posting this here...

I was wondering if anyone can help me understand CYMK color mode. In RGB gradients seem a little transparent.

There is this really cool effect I like which I've previously done in RGB mode, where I gradient a layer, change the blend mode of that layer to color, then have fill the underlying layer in black, then use a brush on a new layer, between the gradient and black layer to show the underlying gradient show through the black layer. Clearly I don't know the techincal term (if there is one) for this particular effect.

Anyway, if I try this in CYMK when I try go to fill the next layer in black, you can faintly see the gradient through the black.

Has anyone noticed this before or am I doing something wrong? Or is there any valid/technical explanation?

I appreciate any help and advise

Thanks
James

[Steve]

CMYK is a much smaller color space then RGB.

Virtually any image you create should be in RGB mode, the only time you would convert to CMYK is if the final image is going to a commercial printer.
Image for the web, desktop printers and even photolabs should remain RGB.

[jamessk]

Thanks Steve! That was very helpful - I still have a lot to learn! Also just noticed I quote CYMK instead of CMYK - ROOOOKIE MISTAKE!!

With regards to the effect I mentioned in my initial post, is this only achievable in RGB? As I'm sure I've seen the same or a similar effect on a flyer which must have been using CMYK

Also does anyone know of any websites/books I can learn more about color?

Thanks
James

[Steve]

....... is this only achievable in RGB? As I'm sure I've seen the same or a similar effect on a flyer which must have been using CMYK ....

You create the effect in RGB not CMYK.
If needed you convert to CMYK the effect should remain.
The conversion dropped the available colors but the effect is still there.

You DO NOT create these images in CMYK.

[jamessk]

Sounds good, how do I convert to CMYK, I've had a little look around Photoshop... is it the Convert to Profile option in the Edit menu?

[Steve]

Sounds good, how do I convert to CMYK, I've had a little look around Photoshop... is it the Convert to Profile option in the Edit menu?

No it's Image|Mode|CMYK Color
You really seem to want to use CMYK and I'm trying to figure out why.
Are you sending some work to a commercial printing company and they told you that's what you need?
If so ask them what profile to use or if they supply the profile.

If you convert and save (overwrite the original) you're going to throw away colors that you'll never get back.

[jamessk]

Yes the design is for a magazine ad and they've requested it to be CMYK and 300dpi

Thanks, I'll ensure I keep a copy of the original before I convert.

[Steve]

Thanks, I'll ensure I keep a copy of the original before I convert.

Excellent idea.
You can use View|Proof Setup with Ctrl+Y (Cmd+Y Mac) to simulate the CMYK output and View|Gamut Warning Shift+Ctrl+Y (Shift+Cmd+Y Mac) to show color problems.