Questions and grain


Dan Margulis <76270.1033@...>
 

Gary writes,

Thank you all for your constructive comments about my color settings.
Some of you mentioned "learning the numbers". I need to know what
this means. and is the subject covered in Dan's book Professional
Photoshop 6?>>

"By the numbers" is the foundation for all successful color correction. In
its simplest form it implies setting an arbitrary light and dark point
somewhere in the image, and correcting all colors that one would expect to
be neutral to be neutral in fact. These are areas where the human visual
system is rather poor in evaluating what it sees, so the assistance of the
Info palette is necessary.

"Learning the numbers" is essentially a bogeyman erected by those who would
like to make successful color correction seem more difficult than it is.
You will hear people say things like, "that Dan Margulis, he can look at a
tree and know that it's supposed to be 53c18m75y. You'll never be able to
do that! What you really need is a calibrated monitor."

In reality, all that one needs to be able to do is to read a value and know
which color--RMBCGY--is being produced. When someone who knows what he's
doing sets a colored object to certain values, it's almost never because he
knows what values are correct, but rather because he's found values that
couldn't possibly be right and has decided to change them to ones that
conceivably could be.

In the example above, I might have originally found, say 40c30m80y. Now,
contrary to what you might hear, I have not memorized values for particular
trees. However, it's not too much of a stretch to insist that a tree should
be *green*. 40c30m80y is not, it's a greenish yellow. Therefore, it has to
change. 53c18m75y *is* a green. It might not be the right green for this
particular tree, but it has to be better than leaving it yellow.

I also recently had a costumer return a print I had enhance because
it was too grainy. The picture was shot on 800 speed film pushed to
1600. The mistake I made was to set the amount too high when I
unsharpened. Not only did the picture look grainy. ther was a color
shift in the grey horse that gave it a blue twinge.>>

If the picture looks grainy, then the mistake is too low of a Threshold,
not too high an Amount. If the Amount were too high, you'd see flecks of
white and black.

If there is a color shift as a result of sharpening, this can be avoided by
sharpening in the L channel of LAB, or, if working in RGB or CMYK, by using
Edit: Fade>Luminosity directly after applying the sharpening.

Dan Margulis


Gordon Pritchard <gordon_pritchard@...>
 

RE:
Thank you all for your constructive comments about my color settings.
Some of you mentioned "learning the numbers". I need to know what
this means. and is the subject covered in Dan's book Professional
Photoshop 6?>>
============================================

In the pre DTP days as well as the days before color monitors were
available, better printers would oftensupply creatives with swatch books of
all the combinations of CMYK -- effectively their printable gamut. The
creative could then simply look at the recipe for the color they wanted and
specify "by-the-numbers" It did not matter whether the color was in a scan
or a synthetic object (e.g. an Illustrator vector graphic) 50C35M --
whatever--was a universal language. In those days all art was basically
built in black and white -- specifying color by screen tint builds by the
numbers. The first time the creative would see color was on an overlay or
laminate proof. Prior to off press proofing the creative would only see
color on a press proof or when the actual job printed.
Scanner operators only recently have had color monitors at their scanner
station. The first time these guys would see color was when a proof was
pulled from the film that the scanner output. So all their color work had to
be done by the numbers.
It is a device dependent way of working in that a specified color would only
apply to that printer. In this workflow model, basically no color that is
seen prior to the contract proof was any particular validity. I.e. pretty
colors on and inkjet or on the monitor are ignored -- only the laminate
proof has validity.
With the advent of DTP and soft (monitor) proofing, many printers abandoned
the swatch books and instead told their customers that they warranted their
color as proofed by one of ther proofing media vendors (e.g. Imation, Fuji,
Dupont etc.) Specify your colors by the numbers and if you like how it
appears on the proof then they will "match" on press. This is still kinda
device dependent (ie must be Imation gamut) however you will theoretically
get the same color from every printer who says that they can match one
common proof media.


thx - gordo

Gordon Pritchard
Commercial Print Specialist
CreoScitex
Vancouver Canada
T: 604.451.2700 ext 2870
C: 604.351.2437
gordon_pritchard@creoscitex.com
http://www.creoscitex.com

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