[argyllcms] Re: Dev Mnfctr/Model default

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 04 Dec 2009 10:29:56 +1100

Pascal de Bruijn wrote:
Is there a specific reason why ArgyllCMS (colprof) uses the following defaults:

  Dev. Mnfctr. = '????'
  Dev. Model   = '????'

Most other tools seem to zero these:

  Dev. Mnfctr. = 0x0
  Dev. Model   = 0x0

While this is everything but critically important, but I'm curious nonetheless.

        The tag definitions in the header file from the ICC website
define the following:

#define icSigUnknownTag  ((icTagSignature) 0x3f3f3f3f)  /* '????' */
#define icSigUnknownType ((icTagTypeSignature) 0x3f3f3f3f)  /* '????' */
#define icSigUnknownData ((icColorSpaceSignature) 0x3f3f3f3f)  /* '????' */
#define icUnknownIntent  ((icRenderingIntent) 0x3f3f3f3f)  /* '????' */

It's noted that these aren't defined in the ICC specification though.

The but Tag Signaures value (hex) 00000000 - 0000005a are registered to Sun 
while the Device Manufacturer Tag and Model Tag registry don't appear to have 
00000000 or 3F3F3F3F ('????') registered or reserved, although it's difficult 
to tell
for sure.

On the other hand the V2 spec says:
"6.5 Tag type definitions
 Value 0 is defined to be of “unknown value” for all enumerated data 

but this isn't necessarily applicable to Signatures, and isn't strictly 
followed by
the ICC spec. itself (some enumerated types have the first value 0, e.g. Device 
Rendering Intent, ParametricCurveFunctionType).

So it's rather unclear what an unknown device manufacturer and model should be 
set to.
I thought that '????' was more obvious that 0x0 though.


Graeme Gill.

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