Date: Wed, 21 Feb 2001 19:00:00
From: Chris Losinger <closinger@checkfreeinvsvcs.com>
Subject: Re: G4 colors (b/w or w/b ?)

> -----Original Message-----
> From: Helge Blischke [mailto:H.Blischke@srz-berlin.de]
> Sent: Wednesday, February 21, 2001 1:53 PM
> To: Chris Losinger
> Cc: 'tiff@olympiakos.com'
> Subject: Re: G4 colors (b/w or w/b ?)
>
>
> Chris Losinger wrote:
> >
> >         hi,
> >
> >         i'm having some trouble telling when a G4 TIFF is
> black on white vs.
> > white on black. the images that are giving me trouble have
> these tags set:
> >
> >         TIFFTAG_BITSPERSAMPLE = 1
> >         TIFFTAG_SAMPLESPERPIXEL = 1
> >         TIFFTAG_EXTRASAMPLES = 0
> >         TIFFTAG_PLANARCONFIG = 1
> >         TIFFTAG_PHOTOMETRIC = 1 (min = black)
> >         TIFFTAG_COMPRESSION = 4
> >
> >         TIFFReadRGBAImage reads them OK and so does my
> special g4 code, but
> > the colors are reversed. Wang's Imaging stuff displays the
> images correctly.
> >
> >         so, i'm wondering, does anyone know what kind of
> magic Wang's stuff
> > could be doing to get the colors right? someone here
> suggested maybe Wang is
> > simply counting pixels and setting white to the color with
> the most pixels
> > (since these are faxes).
> Which app did create the image?

i don't know. the file came to me from a 3rd party.

>Send me a sample file - it may be that
> the progometric
> tag disagrees with the actual image data (I've seen this quite often).
 
        here it is.

        LibTiff reads it as white text on black. Wang's viewer shows it as
black on white (correctly)

        -c
