Re(9): embedded profiles in PDF/Postscript
Re(9): embedded profiles in PDF/Postscript
- Subject: Re(9): embedded profiles in PDF/Postscript
- From: Olaf Drümmer <email@hidden>
- Date: Sun, 6 Jun 2004 21:10:54 +0200
Lab and ICC based color spaces are also colorimetrically defined, but
these are not CalGray or CalRGB color spaces. You are right though
injsofar as CalRGB and CalRGB are not a specifiic color space, but rather
classes of color spaces.
Olaf Druemmer
email@hidden wrote Sun, 6 Jun 2004 11:59:24 -0700
>
CalRGB and CalGray are simply the catch-all terms
>
for RGB and Gray that are colorimetrically
>
defined. They aren't specific RGB or Gray spaces.
>
>
Bruce
>
>
At 5:56 PM +0200 6/6/04, Olaf Dr|mmer wrote:
>
>Roger,
>
>
>
>here is an excerpt from the PDF 1.5 spec wrt CalRGB (see page 218):
>
>
>
>"TABLE 4.14 Entries in a CalRGB color space dictionary
>
>WhitePoint array
>
>(Required) An array of three numbers [XW YW ZW] specifying the
>
>tristimulus value,
>
>in the CIE 1931 XYZ space, of the diffuse white point; see below for
>
>further discussion.
>
>The numbers XW and ZW must be positive, and YW must be equal to 1.0.
>
>
>
>BlackPoint array
>
>(Optional) An array of three numbers [XB YB ZB] specifying the
>
>tristimulus value, in
>
>the CIE 1931 XYZ space, of the diffuse black point; see below for further
>
>discussion.
>
>All three of these numbers must be nonnegative. Default value:
[0.0 0.0 0.0].
>
>
>
>Gamma array
>
>(Optional) An array of three numbers [GR GG GB] specifying the gamma for
>
>the red,
>
>green, and blue (A, B, and C) components of the color space. Default value:
>
>[1.0 1.0 1.0].
>
>
>
>Matrix array
>
>(Optional) An array of nine numbers [XA YA ZA XB YB ZB XC YC ZC] specifying
>
>the linear interpretation of the decoded A, B, and C components of the
>
>color space
>
>with respect to the final XYZ representation. Default value: the identity
>
>matrix
>
>[1 0 0 0 1 0 0 0 1]."
>
>
>
>A CalRGB color space could be converted to an ICC RGB mntr profile I'd
>
>say though I do not know of any tool that does so. The CalRGB mechanics
>
>are based on the CIEBasedABC color space in PostScript Level 2 and
>
>upwards, though in PostScript you can have more transforms than just one
>
>set of transfer curves and one matrix.
>
>
>
>Olaf
>
>
>
>email@hidden wrote Sun, 6 Jun 2004 11:09:24 -0400
>
>
>
>>> Think of it as a poor man's (and limited) colorimetric characterization
>
>>> of grayscale and RGB color.
>
>>
>
>>Do these profiles exist anywhere in an 'ICC' format? Or will I have to
>
>>extract them out of an existing PDF file to open them up wih ColorSync
>
>>Utility? I'm curious to see what I will find out, because I've not
seen them
>
>>documented in the official Adobe PDF 1.5 Specifications anywhere. They are
>
>>mentioned in the specs but not defined.
>
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