Index (this will be updated as the series unfolds)
Part 1a: Importing Files and File Types
Part 1b: Camera Raw
Part 2: Colour
Colour
Which Colour Mode: CMYK or RGB?
Colour Space (example of difference)
Colour Conversion / Proof Setup / Mode Conversion
Part 3a: The Workspace
Part 3b: Working Layers Example
Part 3c: Adjustment Layers
Part 4: Grouping, Masks & History
Part 5: Selection and Paths (Pen Tool)
Part 5b: Healing Brush, Patch or Clone Stamp Tool?
Colour:
For many the whole concept of 'colour theory' may sound about as exciting as a trip to the dentist. At times this may be true, but if you don't get a basic grounding of the subject, you will only end up pulling teeth later.
Which Colour Mode: CMYK or RGB?
Before digital imaging was but a speck on the radar, traditional print processes ruled the roost. The four colour CMYK (cyan, magenta, yellow, and 'key line' or black) model comes from age-old printing - and that's exactly what it's still associated with.
Caption: CMYK is a subtractive colour model. As the colour is derived from reflected light, the accumulation of all colours theoretically formulates black (i.e. no light reflected).
RGB (red, green, blue), on the other hand, deals with projected light and is for use where screen-based digital displays are concerned (i.e. white light).
Caption: RGB is an additive colour model. As the colour is derived from incidental light, the accumulation of all colours theoretically formulates white.
The burning question is why are the two models so different? Why not print out from RGB or have a CMYK image saved for web?
Well, you could do either - but the results will be wholly inaccurate. Each colour model occupies a space in an available colour density (sounds more complicated than it is, don't resign to the dentist yet).
In the given space, CMYK occupies a different and essentially smaller number of colour possibilities than RGB.
As the printer will have ink that correlates to a CMYK output it is important to maintain this association with the file itself, otherwise the interpretation from screen to print will be different to what your eyes see.
Colour Conversion:
When converting colour from RGB to CMYK in Photoshop, there is very likely to be colour loss (often described as 'lossy') when coming to print.
There's a great deal of debate about which colour space to use and when - should the file be set to CMYK from the outset? Or should all on-screen corrections take place in RGB, offering best colour representation to the eye, then converted to CMYK for print?
It's largely down to preference. In Photoshop, however, there's a clever little way of getting the advantages of both (sort of).
Under the View menu, select Proof Setup and Working CMYK from the drop menu.
Then to toggle CMYK-appropriated view on, go back to View and toggle Proof Colors on and off (shortcut Ctrl+Y).
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The difference is immediately apparent, but allows you to work in RGB with an understanding of how the CMYK conversion will appear. This is distinctly useful if requiring both a web version and print version to look identical - the RGB can be “toned down” to be inline with the equivalent print, for example.
Caption: The colour differences between CMYK and RGB, presented to you with the utter irony of jpeg compression
When you're sure as to which mode you want to work in, and at what point to convert, conversion is simple.
Image > Mode > the present mode will be represented by a tick, select the mode which you wish to convert to
Continue to 'Workspace, Basic Layers' and Part 3
