1993.08.21 02:03 "Re: help on TIFFReadRGBAImage", by Yip Chi Lap

Hello,

I suspect that you wrote the TIFF file with the default Orientation which is TopLeft. You don't indicate how you created the TIFF file. ppm2tiff looks to force all data to have a TopLeft origin.

Karsten Spang <krs@kampsax.dk> also asked how the TIFF file was generated.

I used ppm2tiff to convert the file and tiffinfo reports this:

TIFF Directory at offset 0x18
  Image Width: 3 Image Length: 5
  Bits/Sample: 8
  Compression Scheme: Lempel-Ziv & Welch encoding
  Photometric Interpretation: palette color (RGB from colormap)
  FillOrder: msb-to-lsb
  Document Name: "small.pnm"
  Image Description: "converted PNM file"
  Orientation: row 0 top, col 0 lhs
  Samples/Pixel: 1
  Rows/Strip: 2730
  Planar Configuration: single image plane
  Color Map: (present)

So the "(x,y)" in the sentence "Note that the raster is assume to be organized such that the pixel at location (x,y) is raster[y*width+x]" in the man page of TIFFReadRGBAImage refers to the 'normal' cartesian coordinates but not the (row,col) coordinate relative to the image, I suppose?

Regards,
  Beta.

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