the digital printing house LSI has some problems with rendering
grayscale illustrations correctly. The instructions given below
were prepared for Photoshop users. Perhaps some kind soul can
trurn them into equivalent instructions for Gimp. Then I can pass
them on to the publishing community.
1) In PhotoShop (I'm using 6.0), load the grayscale picture or photo you
want to print with LSI. Save it as a TIFF and adjust the image to the size
and resolution you will be using in the final document (usually 300 dpi,
but could be 600 dpi).
2) Select the Color Sampler tool. This will give you 4 possible eyedropper
selections which, as you make them, will be listed under the Info palette.
3) (To do the following, you may want to magnify the areas you are
concentrating on.) On your photo, find the lightest point, or any area you
want to print as all white. Click on this with the eyedropper. Next, find
the darkest point in your photo, or any area you want to print as all
black. Click on this with the eyedropper. Do the same thing with the
lightest area you want to print (be visible) as gray, and the darkest area
you want to NOT print as all black (in other words, to have some shadow
detail). Under Info palette, you should now have percentages listed for all
4) Now go to Image:Adjust and select Auto Levels. See how this affects the
% settings in your Info palette. You will see each original setting with
the new setting to the right of it. Usually your low %'s will go down and
your high %'s will go up.
5) Looking at the new settings: If your #1 point (white point) is now below
5%, then your white areas should print as white. If your #2 point (black
point) is above 93%, your black areas should print as black. If your #3
point (lightest gray area) is around 10-15%, it should print as light gray.
Your #4 point is not always necessary, but anything under 90% should print
dark but also show some shadow detail. If the new percentages fall within
these boundaries, you should be okay. If not-if either the white points or
the black points are too low or too high-you can make further adjustments
6) Go to Layer:New Adjustment Layer:Curves. You'll see a box with a grid
labeled "Channel: Gray." The lower left corner should be your maximum white
point, and the upper right corner your maximum black point (visible on the
gradient strip to the left of and below the box-if it's the opposite, you
can reverse it by clicking once on the gradient strip).
7) A line runs diagonally from lower left to upper right of the box, with a
small square at each end of the line. To adjust your white point, put the
pointer over the lower left square and hold down the left mouse button. If
you move the square along the bottom line to the right, you will see the
%'s in the Info palette decrease. If you move the square up the left side
of the box, you will see the %'s increase. Which direction you move depends
on what changes you want to make in the %'s. Just be aware that all 4
percentages will be affected to some degree at some point. It's best to
keep all your adjustments here to the barest minimum that will give you the
results you want for all 4 points.
8) To adjust the black point, make the same sort of adjustment to the
square at the upper right corner of the box. Again, be sure to watch how
the %'s for all 4 points are affected.
9) Once you have all 4 points in the Info palette registering within the
limitations you want, just save the photo. (I suggest saving it now anyway
before going on to any of the next adjustments.)
10) If the above adjustments in Curves don't give you results close enough
to what you want, you can play with tweaking the diagonal line that runs
across the box. You can grab it (with your left mouse button) anywhere
along its length and bend it up or down. You can also slide up and down it
as you bend it. Watch what happens to the percentages. You can even bend it
up in one section and down in another. You can put as many points along the
line as you want. In fact, if you're feeling adventurous, I suggest playing
with this for a while to get the feel of it, even if you're not going to
use it right now. If you screw up, you can undo any of your adjustments by
grabbing any point you've added to the line and sliding it along the line
until it's off the edge of the box.
11) One important caveat: Don't pay attention to what your photo looks like
on your screen; it may or may not look the way it will when printed by LSI.
If you stick to the percentages in the Info palette, you should get the
results you want.
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