2004.01.02 06:52 "Re: [Tiff] Non Color - Compression in 3.6.X", by Carl Collin

I don't know what to tell you. This is all the information I have...

Tiffinfo reported this to me on my original "greyscale" file.

TIFF Directory at offset 0xd4
  Subfile Type: (0 = 0x0)
  Image Width: 1600 Image Length: 2000
  Resolution: 200, 200 pixels/inch
  Bits/Sample: 8
  Compression Scheme: None
  Photometric Interpretation: min-is-black
  FillOrder: msb-to-lsb
  Orientation: row 0 top, col 0 lhs
  Samples/Pixel: 1
  Rows/Strip: 19
  Planar Configuration: single image plane
  Software: Oi/GFS, writer v00.06.02

I then tried to perform this command to compress: tiffcp -c jpeg ds1encounter1.tif compressed.tif

and got this error:

TIFFReadDirectory: Warning, ds1encounter1.tif: unknown field with tag 32934 (0x80a6) encountered.
ds1encounter1.tif: Warning, incorrect count for field "Tag 32934" (0, expecting 1); tag ignored.
JPEGSetupEncode: RowsPerStrip must be multiple of 16 for JPEG.

So I performed this command: tiffcp -r 16 -c jpeg ds1encounter1.tif compressed.tif

and got this error:

JPEGLib: Bogus input colorspace.

So I performed this command: tiffcp -r 16 -c jpeg:r ds1encounter1.tif compressed.tif

and got no error, but when I tried to view the image using "display" which is from ImageMagick I get this error:

display: Sorry, can not handle RGB image with Color channels=1. (compressed.tif)

So I thought maybe ImageMagick is just f'd up, so I tried to reverse the compression ala "tiffcp -c none compressed.tif uncompressed.tif" and while the file size has expanded, the file is still reporting the same error in display (ImageMagick)

display: Sorry, can not handle RGB image with Color channels=1. (compressed.tif)

Now the really interesting point again is that this works fine for if my original file has this for its tiffinfo:

TIFF Directory at offset 0x8
  Subfile Type: (0 = 0x0)
  Image Width: 849 Image Length: 933
  Resolution: 72, 72 pixels/inch
  Bits/Sample: 8
  Compression Scheme: LZW
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Rows/Strip: 3
  Planar Configuration: single image plane
  Photoshop Data: <present>, 2968 bytes
  Predictor: horizontal differencing 2 (0x2)

It seems for all files that have a Photometric Interpretation of RGB color the compression schema works fine.

The other "really interesting thing" is that those broken compressed/uncompressed files above that don't work in the ImageMagick program or in the Wang viewer work FINE in Irfanview. So what the hell is going on?

Any ideas....

I can send files to anybody whom can help out, I'm just trying to figure out why the compression and decompression leaves the files in a state that seems can only be read by some programs.

Thanks!