Tiff RGB>Indexed>CMYK

Tiff RGB>Indexed>CMYK

Post by Miller Tayl » Wed, 25 Dec 1996 04:00:00



This message will show my great ignorance in TIFF and how it is handled by
Photoshop, but I need you to enlighten me.

Note: Throughout the description I use the term "printer".  This refers to a
printing company, not a PC-attached device.

I am taking cartoon are and preparing it for a book to go to the printers to
produce using process colors.  I only need 10 colors for the art.  I am
scanning it in 24bit RGB.  A typical drawing would be 3.5 Mb on the disk.  I
then convert it to 4 bit indexed color and clean up the drawings replacing the
colors using my own defined color table.  The indexed color file is now 124k
in size on the disk.  To prepare for Pagemake and the printer, I convert it
into CMYK to ge the process colors.  The file on the disk is now 320k.  I then
place the drawings in Pagemaker and place on a ZIP disk for the printer.

The issue:
The file size is very advantageous to me since it is 10% of the original
scanned file.  Since I don't fully understand the process, I am concerned
though that something is lost that will cause problems when the printer
handles the file.  If I convert the 3.5 Mb RDB image to CMYK the result is
3.61 Mb.  How is the CMYK information stored after the 4 bit indexed
conversion, allowing it to save disk space?  Does the small CMYK file lack the
information it needs to give me the expected results from the printer?  

Any help would be greatly appreciated.  I am ready to push forward with 32 of
these drawings, but I want to know that I'm doing it in a sound manner.  
Thanks, and I apologize for my ignorance.

Miller Taylor

 
 
 

Tiff RGB>Indexed>CMYK

Post by Vlad Lukiche » Wed, 25 Dec 1996 04:00:00



> I am taking cartoon are and preparing it for a book to go to the printers
to
> produce using process colors.  I only need 10 colors for the art.  I am
> scanning it in 24bit RGB.  A typical drawing would be 3.5 Mb on the disk.
 I
> then convert it to 4 bit indexed color and clean up the drawings
replacing the
> colors using my own defined color table.  The indexed color file is now
124k
> in size on the disk.  To prepare for Pagemake and the printer, I convert
it
> into CMYK to ge the process colors.  The file on the disk is now 320k.  I
then
> place the drawings in Pagemaker and place on a ZIP disk for the printer.
> The issue:
> The file size is very advantageous to me since it is 10% of the original
> scanned file.  Since I don't fully understand the process, I am concerned

I see two variants: or I haven't understood your question, or CMYK-file is
small because of the used compression (such as LZW). TIFF-files compression
is made on recurrence of points of same colour. In yours previously indexed
and cleaned image is a lot of such sequences.

Vlad

 
 
 

1. help rgb->cmyk, ycc->cmyk, TIFF

Hi,

I am interested in information on how to convert from Kodak PhotoCD (YCC)
to CMYK, from RGB to CMYK, and on TIFF (versions 5.0 and 6.0).
Any info on these or pointers to who might know would be much
appreciated.
Many thanks

Hamish McNaughton

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10. >>>>>>>>>>>>>>>>>>>>>

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