Design For Print - Workshop 2

Colour Modes In Photoshop

It is important to always make sure that before you send off any work to be printed that you make sure it's in CMYK, as the default colour mode for Photoshop is RGB, which will make some colours such as bright greens go duller as they lie outside the CMYK gamut.

You can use the Gamut warning in photoshop to show you what areas of your screen won't print in CMYK by turning them grey. This feature can be accessed in the View Menu. You can edit the image by altering the Hue/Saturation, Levels, and Curves in the Adjustments menu. When there are no large grey areas, the image is ready for print after it has been converted to CMYK.

If you change the colour mode from RGB to CMYK without doing this, Photoshop will choose the nearest CMYK colour to use in place of any colour that is used that can't be reproduced. To preview what this would look like you can use the Proof Colours option in the View menu.

Using the colour picker shows you if a colour can't be reproduced in CMYK via an exclamation mark within a triangle next to the little swatch. Clicking on the tiny square below it automatically moves the colour picker to the closest CMYK colour. The little cube underneath it does the same thing to indicate a web-safe colour.

Using Spot Colours

Method 1

Image -> Mode -> Greyscale
Image -> Mode -> Duotone

-> Click on the colour box
-> Choose the Pantone colour box you want to use
-> Alter curves

-> File -> Save as
-> Format
-> Photoshop

Method 2

Image -> Mode -> Greyscale
Channels -> Menu -> New Spot Channel

-> Coloured Square
-> Colour Libraries
-> Choose Colour

The new channel acts like a layer mask, double click on the channel to change the colour

-> Save as
-> Ensure "Spot Colours" box is ticked
-> TIFF or Photohop