OT: What's the easy way to adjust black and white...
OT: What's the easy way to adjust black and white...
- Subject: OT: What's the easy way to adjust black and white...
- From: Frederick Park <email@hidden>
- Date: Fri, 09 May 2003 01:17:42 -0400
>
Steven Kornreich wrote:
>
I need to adjust BLACK in RGB mode in PS. I am not sure how to do this. Can
>
someone recommend a good website for info?
Read: Professional Photoshop/Dan Margulis or Channel Chops/Bert Monroy
>
All I know is to make an adjustment layer but not sure what else to do.
---------
You've run up on a great issue. in PS 6 or 7 here is one method that works
like a champ.
First the commands then the reasoning:
COMMANDS -
1. Open RGB file, convert to Lab
< Image/Mode/Lab Color >
2. Duplicate Layer
< Command J >
3. Apply New Adjustment Layer
< Layer/New Adj. Layer/Curves >
4. in the dialog box select "group with previous layer"
(Curves dialog box appears...)
5. In the Curves dialog box place the Highlight in bottom left corner by
touching the double arrows in the bar below the curves window (Additive
Mode) with your cursor and then push or pull the curve to your hearts
content! By default the curve on screen is Luminance or the "L" channel.
6. When you're done select "Save" (and name it for use with other images) or
select "OK" and then turn the effected layer off and on
< by clicking the eye icon to the left of the layer on top >
to view the difference between the original and your adjusted layer. If you
like you may send the file back to RGB (save the layers when asked) and
print directly from this file or save it as .psd then flatten the file
saving again as .tif for another RGB printer.
REASONING -
1. RGB is 8 or 16 bits of 256 steps of dark to light data that is indeed not
black. The L channel ("Luminance" - sound familiar?) of Lab Color is nothing
but true black and white data referenced directly from the RGB file. (The
"a" channel is +red and -green, the "b" channel is +yellow and -blue). So
with this step you've gained access to the actual black and white areas of
your file while the color data is unaffected! This is also the place to come
for sharpening an image (unsharp masking) while desiring to keep color true
to your original intent - a recommended "final" step before output.
2. By duplication ( a workflow issue) you have only to trash the top layer
with a single mouse move rather than "revert" or use the History pallet.
Too, you have a comparison layer with which to judge changes by using visual
or numeric means.
3. Adjustment Layers, saved in .psd format only until PS 7 came along,
permit access to data shifts with any pallet tools available in that dialog
window that are otherwise inaccessible unless you revert or go to "History".
This, it seems you know.
4. I include "group with previous layer" selection because you're adjustment
will now allow a contrast and comparison. Otherwise the Adj. Layer would be
applied to all layers beneath it.
5. Curves is my pallet of choice for adjustment of most global and local
color changes. Note that Highlights/top right (CMY or subtractive color) is
the default setting when curves is first opened. Visually, the baseline
"gray scale" represents input while the vertical "gray scale" on the left
represents output. Think about it. It doesn't "really" matter.
6. (Another work flow issue) Files may have the same name when endings or
extensions (.tif .eps .jpg) are employed to designate use. (Example:
"file.psd" is a "work in progress" indicator in my workflow while "file.tif"
is ready to go out the door.
Hope this helps.
Frederick Park
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