Re: Changing White to Yellow on a pixel by pixel basis
Re: Changing White to Yellow on a pixel by pixel basis
- Subject: Re: Changing White to Yellow on a pixel by pixel basis
- From: "Jonathan Levi, M.D." <email@hidden>
- Date: Tue, 15 Aug 2006 21:53:08 -0400
On Tue, 15 Aug 2006 09:32:49 -0400, Chris Tangora
<email@hidden> wrote:
Date: Tue, 15 Aug 2006 09:32:49 -0400
I'm hoping to find a way to do some fine tuned color management and
I can't find a good way to do it yet, hoping someone has a good idea.
What I'm doing right now is taking a CMYK TIFF and turning it into
an RGB PNG via an external application (Binuscan). The problem is
that the white background isn't truly representative of the paper we
print on (newsprint). I was hoping to find some way to script color
sync or image events or something else entirely that would take the
255, 255, 255 in RGB or the 0, 0, 0, 0 values in CMYK and convert
them to another color, only affecting that single color though,
pretty much a pixel by pixel check. Does anybody know of a built-in
apple application that can do this or any other way of doing it?
I do such pixel-by-pixel editing now and then. One venerable file
format I've found useful for this kind of work is the XPM format, by
Arnaud le Hors (sp?) It's human-readable; you can figure out very
quickly what's being done and make simple modifications by hand,
using sed, AppleScript's or Emanuel's find/replace commands, etc.
Convert your graphic to XPM format using GraphicConverter,
Imagemagick, etc, make your substitution, and convert back to
original format.
A quick example: here's an XPM file for a 9x9 pixel graphic. The top
three rows are blue, the middle three rows, red, the bottom three,
white:
jonathan$ echo; cat simplePainting.xpm
/* XPM */
static char *simplePainting[] = {
/* width height ncolors chars_per_pixel */
"9 9 3 1",
/* colors */
"A c #FFFFFFFFFFFF",
"B c #FFFF00000000",
"C c #00000000FFFF",
/* pixels */
"CCCCCCCCC",
"CCCCCCCCC",
"CCCCCCCCC",
"BBBBBBBBB",
"BBBBBBBBB",
"BBBBBBBBB",
"AAAAAAAAA",
"AAAAAAAAA",
"AAAAAAAAA"};
A pale yellow color used in the Eudora mailbox icon has RGB values
{255, 255, 239}; the corresponding XPM color definition is
#FFFFFFFFEFEF, If you substitute this string in place of #FFFFFFFFFFF
in the line
"A c #FFFFFFFFFFFF",
above, then open the XPM in GraphicConverter, etc., you'll see all
the white pixels replaced by yellow pixels. A simple modification of
the above would allow you to swap in a whole range of colors ikf you
kept the desired color definitions in a separate cache,
One disadvantage of this method is that although the XPM format can
handle arbitrarily many colors, both GraphicConverter and ImageMagick
silently reduce the number of colors during conversion if there are
"too many" colors (>256?) in the original. On the other hand,
newsprint shouldn't require that many colors, I imagine.
HTH,
Jonathan
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Applescript-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden