Pro tricks for mastering colour
20 The Professional Photoshop Book
CONVERT TO CMYK
WITHOUT LOSING
SATURATIONCHANGE THE CHANNEL
“Much like a painting gamut, a gamut in computer
graphics and printing is the range of colours that a
computer or printer is able to produce,” explains
Westwood. “The ideal method of preparing items for
print is to keep as many original colours as possible
and only change those that would be affected by a
mode change into CMYK. Unfortunately, some
colours simply don’t exist in ink, so some of those
vibrant reds, hot pinks, and mint greens might need
to be adjusted and some saturation may be lost, but
you can get close to the original RGB image with
some adjustment. Luckily Photoshop comes with its
own colour management display options called
‘gamut warning’ and ‘proof colours’. Both are
available in the View menu – make sure the proof
setup is set to display a CMYK gamut in View>Proof
Setup>Working CMYK.
Selecting Proof Colours will display what the
image will look like when converted into the CMYK
colour mode, while Gamut Warning will highlight
exactly what colours will be affected in the change.
From here, it’s possible to make a number of colour
adjustments while still within an RGB format with
the Hue/Saturation adjustment layer [Window>
Adjustments] or the Replace Color adjustment
[Image>Adjustments>Replace Color].”Aaron Campbell likes to use Channels to “quickly
adjust the colour of the atmosphere in my image,
which, most commonly for me, is an illustration.
Just doing a quick Levels adjust on one of the
Channels can make it easy to change the hue of the
large spots of coloured glowing parts of my pieces
without having to go in and change each part
independently. Let’s say I have eight glowing
mushrooms in my piece that all have an ambient
green glow and I want it to be more green andstronger, I can go in the Green channel and do a
Levels adjust to slide the whites up a bit or brush in
the parts I want to be more green, instead of
adjusting them one by one.”
If he’s using Replace Color, for instance to change
the colour of someone’s clothing in a photo, he’ll “try
to have as much fuzziness as possible to make sure
all of the colour gets changed, then just brush in any
parts of the coloured area that didn’t change with a
soft brush on Overlay or Soft Light.”CREATE ONLINE
IMAGES DIFFERENTLY
“Preparing colour images for the web, social media
and so on, does need a differing colour approach,”
says Paul Sherfield. “As the content will be viewed on
consumer devices; computer monitors, tablets and
smartphones with screens that in the main have an
sRGB gamut this is then of course the profile to use.
However do not embed the profile as this will
increase the file size of the image. Most web
browsers do not yet support ICC colour management,
but just assume sRGB. So convert your images to
sRGB, around 96dpi. It is best to talk to the web
developers involved as regards the file format, but is
in doubt use JPEG. There is a Web colour settings file
in the Color Setting menu in Photoshop.”
Colour management is becoming more
automated, Sherfield explains, adding that “Used
correctly Adobe CS/CC is a repro shop in a box.”
However “knowing what colour setting files to use,
and how to make and install customised ones does
still require knowledge and training.”© Jon Westwood© Aaron Campbell016-027 Colour Feature.indd 20 06/10/2015 16: