2008.02.12 00:29 "RE: [Tiff] TIFFReadRGBAImage rendering upside-down", by Mick O'Neill

Yes, I looked at the orientation tags, and they seemed to all indicate ORIENTATION_TOPLEFT ok. I have other TIFF files, generated by the same Kofax software, in fact, that all come out OK. There must be something else somewhere.

The only tags that I noticed that are a bit odd are the TIFFTAG_YCBCRSUBSAMPLING in the OJPEG compressed images (Missing, and the Jpegs indicate [2,1]), and the TIFFTAG_FILLORDER tags in the CITT compressed images with a value of FILLORDER_LSB2MSB, which is unusual.

I cannot get onto the CVS to get the latest version - wondering if you may be able to send me a copy of the tif_getimage.c and perhaps tif_read.c modules you used so I can compare, and perhaps find out exactly what it is that is different?

I don't mind flipping the images - in fact, I am loading the generated RGBA into ImageMagick for further processing - I just need to know when to do it.

Cheers,

O'Neill
Software Engineer

-----Original Message-----
From: Frank Warmerdam [mailto:warmerdam@pobox.com]
Sent: Tuesday, 12 February 2008 2:03 AM
To: Mick O'Neill
Cc: tiff@lists.maptools.org
Subject: Re: [Tiff] TIFFReadRGBAImage rendering upside-down

Mick O'Neill wrote:
> Hi,
>
> I have some odd TIFF files here (that do have a subsampling error
> being reported for the OJPEG compressed images) that, when I call the
> TIFFReadRGBAImage function, renders the RGBA upside down (flipped, not

> rotated). I was wondering if there was something in the TIFF headers
> that tell me this is happening? Or perhaps some other info elsewhere.
> There are some applications around that read these TIFFs correctly,
> and others that will not read them at all.
>
> libtiff version 3.9.0 Beta
>
> Any ideas appreciated.

Mick,

The tiffinfo reports:

    Orientation: row 0 top, col 0 lhs

Which is (I believe) the default case where the first pixel in the file
is the top left corner of the image. I also ran tiff2rgba with the
current development version of libtiff and tiff2rgba and it came out
with the first page "right side up", so I'm surprised you are having
problems.

Best regards,
--

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