LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
March 2006
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
2006.03.31 16:05 "Re: 16-bit TIFF to 8-bit BMP/TIF ???", by Bernie Pallek
> I am in the process of writing a program using openCV > that analyses 8 bit images. The problem I have is that > images produced from a fluorescent camera are > 16 bit unsigned greyscale TIFF images (industry > standard). > ... > The way I would like to do this is to get every pixels > intensity value (16 bit) and Square root it to bring > it into the range between 0 and 255. It sounds like you'll want to do something like this: - open original TIFF - create new TIFF as 8-bit greyscale - begin loop -- read one scanline worth from original (see TIFFReadEncodedStrip) -- normalize the scanline (run through each pair of octets, treating them as a 16-bit word, do your sqrt(), and store in another buffer) -- write one scanline to new file (see TIFFWriteEncodedStrip) - end loop when all scanlines have been processed - close new file - close original file You'll probably want to set these tags, at least, before writing your data: TIFFTAG_PHOTOMETRIC TIFFTAG_IMAGEWIDTH TIFFTAG_IMAGELENGTH TIFFTAG_SAMPLESPERPIXEL (probably 1) TIFFTAG_BITSPERSAMPLE (probably 8) TIFFTAG_ORIENTATION (ORIENTATION_TOPLEFT) TIFFTAG_PLANARCONFIG (probably PLANARCONFIG_CONTIG) TIFFTAG_ROWSPERSTRIP TIFFTAG_COMPRESSION Note, you don't have to write your directory stuff explicitly; it will be done automagically (at least for me, it worked out that way).