1997.01.10 15:55 "TIFFRead/WriteScanline question", by Sven Devriese

Hello all,

the man page for TIFFWriteScanline mentions that for Planarconfiguration = 1 (PLANARCONFIG_CONTIG) "the library does not pack the block-interleaved samples". I guess this means that the bit planes are not separated before the data is written to file.

Similarily, the man page for TIFFReadScanline says: "The data are returned decompressed and <marshalled> but are otherwise packed." It also says at the bottom that if you want to unpack the block-interleaved samples (I think that's contiguous pixel data e.g. RGBRGBRGB, right ?) you have to use the strip- and tile-based interfaces to read these formats.

If I understand this correctly, I can read/write compressed scanlines of a plane-separate image (i.e. pc = 2) but they are compressed differently than when I read/write scanlines of the equivalent block-interleaved (i.e. pc = 1) image.

Or does it mean that I just cannot read/write compressed TIF files using the scanline interface?

I need to know because, for incorporating libtiff into our own software, I may only use the scanline interface for reading/writing pixel data.

I think maybe the terminology is getting to me. Can anyone clarify this for me?

Thank you for your time.