.NET Framework - TiffBitmapEncoder bug?

Asked By Robert Simpson

24-May-07 06:58 PM

I've finally nailed down a problem with some TIFF's I've been generating in
.NET, and wanted to know where the blame may lay :)

I have some pretty simple code which saves a TIFF in Ccitt3 format.
However, when opening the resulting TIFF in something like Paint Shop Pro X
(as well as some other 3rd party viewers), the image is completely distorted
and horizontal bars appear all over the page.

I did some digging, and ran LIBTIFF's "tiffinfo" program against the TIFF's
coming out of my program.  Invariably, tiffinfo complained "Bad value 0 for

Upon further research, I read in the TIFF spec:

-----
FillOrder
The logical order of bits within a byte.
Tag = 266 (10A.H)
Type = SHORT
N = 1
1 = pixels are arranged within a byte such that pixels with lower column
values are
stored in the higher-order bits of the byte.

2 = pixels are arranged within a byte such that pixels with lower column
values are
stored in the lower-order bits of the byte.
-----

As you can see, there is no "0" value documented.

I went into the binary file and manually altered the FillOrder field in the
TIFF to change it from 0 to 1, and viola -- PSP X and the other 3rd party
viewers were magically able to open and view my TIFF without any issues.

So ... my question(s) are:
I never set the fillorder, and I expect the TiffBitmapEncoder to do so ...
my saving method is nothing more than:

TiffBitmapEncoder encoder = new TiffBitmapEncoder();
encoder.Compression = TiffCompressOption.Ccitt3;
BitmapFrame frame = BitmapFrame.Create(target);
encoder.Frames.Add(frame);
using (FileStream fs2 = new FileStream("c:\\out.tif", FileMode.Create,
FileAccess.ReadWrite, FileShare.Read))
{
encoder.Save(fs2);
}

I even tried setting the fillorder progammatically with:

using (FileStream fs2 = new FileStream("c:\\out.tif", FileMode.Open,
FileAccess.ReadWrite, FileShare.Read))
{
decoder = new TiffBitmapDecoder(fs2,
BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
InPlaceBitmapMetadataWriter inmeta =
decoder.Frames[0].CreateInPlaceBitmapMetadataWriter();
if (inmeta.TrySave())
{
inmeta.SetQuery("/ifd/{short=266}", 1);
}
}

... but this didn't work.  So what gives?  For now I've resorted to opening
the file stream after saving, reading the TIFF header, and rewriting the
FillOrder tag myself.

Robert

28-May-07 09:17 PM

Strange the encoder writes the FillOrder field unset.  My answer was going
to be the same as what you have resorted to, opening the image after saving,
seek the position of the offending FillOrder field, and use
BinaryWriter.Write(Convert.ToInt16(1));.

Andrew

19-Jul-07 01:17 AM

I noticed that you had some problems with the InPlaceBitmapMetadataWriter. You may be interested in a new sample that I posted: http://blogs.msdn.com/rwlodarc/archive/2007/07/18/using-wpf-s-inplacebitmapmetadatawriter.aspx
The sample is for JPEG, but can easily be modified for TIFFs.