Graphics Programs Reference
In-Depth Information
at a Las Vegas Blackjack table. What are the right CMYK values for Cau-
casian skin tones for SWOP? What values for Eurocoated? What values
for an Iris printing on rag paper versus an Epson 4000 printing onto
Enhanced Matte paper? I think you get my point.
Working numerically still has great value. I discussed how well-
behaved RGB working spaces produce a neutral when equal proportion
of red, green, and blue are present. Producing a neutral in any of the
RGB working spaces discussed is quite easy. The tools Photoshop provides
for setting neutrals, like the various eyedroppers, will work wonderfully
in such cases. We know that the blackest black possible is R0/G0/B0 and
the whitest white is R255/G255/B255. The benefit of good print/output
profiles is that the info palette shows us the numbers based upon specific
devices.
Editing in a print/output space is tricky because there are so many
possible numeric values for the same colors. Yet the output profile is our
guide. We can also edit in an output space numerically if we keep an eye
on ratios. Suppose you have an image in Adobe RGB (1998) while you
soft-proof for a Fuji Pictography 4000. On the soft proof, you see that the
red of a model's dress appears a bit too yellow based on the soft proof.
Perhaps the info palette shows soft proof values or R255/G51/B51. Using
the appropriate selective color correction tools in Photoshop, you can
work to raise the blue value from 51 to a higher value. As you do this,
you see the red become less yellow on-screen due to the ICC profiles pro-
ducing a soft proof. We may not know that the correct numeric value
should be R255/G51/B71 before editing. Using the info palette based on
an output profile and the display, we can produce the color desired. Using
just a calibrated display or just numbers can work, but why not use both?
Good color management allows both tools to be used and better, to com-
plement and support each other.
When working with numbers, at what value should I set my high-
light and shadows? The output profile will play a role in the resulting
values of both. Since you might be making multiple print/output con-
versions, it's important to leave some headroom in the master RGB
working space document. I generally advise users to scan a bit flat to
leave some numeric values and avoid
clipping
the data. If you are shoot-
ing with a digital camera, this is a bit trickier unless you have total control
over the lighting of the subject. I hate to make general numeric recom-
mendations since “your mileage may vary,” but consider keeping the
specular highlight
around 248 to 250 in all channels, and the darkest
black around 5 to 8 in all channels. This will allow the conversion into
print/output space headroom to avoid clipping. If you work in high-bit
(16-bits per color), then you can adjust the highlights and shadows based
on the output profile with far less data loss. While the document is in
the RGB working space, you can set the highlight and shadow values
while viewing a soft proof, while keeping an eye on the info palette set
to
Proof Color
. Do these edits on a duplicate file since you will alter the
Defintion
Clipping:
The result of
taking tones and mapping
them to the extreme end
of the tone scale. When
working with digital
images, the highlight and
shadow values are a fixed
scale. In the case of an 8-
bit file, level 255
represents the whitest
white and level 0
represents the blackest
black. Clipping forces
pixels to pure white (level
255) or pure black (level
0). If a user had a full tone
image over this scale but
produced an edit in
Photoshop to move all
values from 250 to 255,
values 251 to 254 would
be clipped to white. All the
tones that show the subtle
differences from 251 to
254 would all be clipped
to pure white (255).
Defintion
Specular highlight:
Brightest highlight in an
image that may or may
not have a printable dot.
