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diff --git a/tiff/contrib/pds/README b/tiff/contrib/pds/README deleted file mode 100644 index b9abc6b..0000000 --- a/tiff/contrib/pds/README +++ /dev/null @@ -1,90 +0,0 @@ -Date: Fri, 01 Aug 1997 20:14:52 MDT -To: Sam Leffler <sam@cthulhu.engr.sgi.com> - -From: "Conrad J. Poelman (WSAT)" <poelmanc@plk.af.mil> -Subject: Potential TIFF library additions - -Delivery-Date: Fri, 01 Aug 1997 19:21:06 -0700 - -Sam, - -You probably don't remember me, but I sent in a couple of bug fixes -regarding the TIFF library about a 16 months ago or so... - -I just wanted to send you two other additions that I have made to our -local version of the TIFF library in hopes that you will want to -incorporate them into your next major release of the TIFF library. -(These additions are based on TIFF version 3.4beta31, but they sit on -top of the library so they shouldn't be much trouble to incorporate them -into any more recent version.) They are internally documented to a -reasonable extent and we've been successfully using them in our code -here for over a year. If you think they would make good additions to the -TIFF library, I'd be happy to clean them up more, document them more, -and/or integrate them with the latest version of the TIFF library, but I -figured I'd see if you were interested in using them before I went to -all that trouble. - -TIFF Image Iterator -------------------- -Your ReadRGBA() routine works well for reading many different formats -(TILED, STIP, compressed or not, etc.) of the most basic types of data -(RGB, 8-bit greyscale, 8-bit colormapped) into an SGI-style data array, -and serves as a good template for users with other needs. I used it as -an exmaple of how to make an iterator which, rather than fill a data -array, calls an arbitrary user-supplied callback function for each -"chunk" of data - that "chunk" might be a strip or a tile, and might -have one sample-per-pixel or two, and might be 8-bit data or 16-bit or -24-bit. The callback function can do whatever it wants with the data - -store it in a big array, convert it to RGBA, or draw it directly to the -screen. I was able to use this iterator to read 16-bit greyscale and 32- -and 64-bit floating point data, which wasn't possible with ReadRGBA(). - -I have tested this routine with 8- and 16-bit greyscale data as well as -with 32- and 64-bit floating point data. I believe nearly all of our -data is organized in strips, so actually I'd appreciate it if you had -some tiled images that I could test it with. - -It should certainly be possible and would be cleanest to reimplement -ReadRGBA() in terms of the image iterator, but I haven't done that. - - -Private Sub-Directory Read/Write --------------------------------- -TIFF-PL is a Phillips Laboratory extension to the TIFF tags that allows -us to store satellite imaging-specific information in a TIFF format, -such as the satellite's trajectory, the imaging time, etc. In order to -give us the flexibility to modify the tag definitions without getting -approval from the TIFF committee every time, we were given only three -TIFF tags - a PL signature, a PL version number, and PL directory -offset, which lists the position in the file at which to find a private -sub-directory of tags-value pairs. So I wrote two routines: -TIFFWritePrivateDataSubDirectory(), which takes a list of tags and a -"get" function and writes the tag values into the TIFF file, returning -the offset within the file at which it wrote the directory; and -TIFFReadPrivateDataSubDirectory(), which takes an offset, a list of -tags, and a "set" function and reads all the data from the private -directory. The functions themselves are pretty simple. (The files are -huge because I had to basically copy all of the tif_dirread.c and -tif_dirwrite.c files in order to access the various fetching routines -which were all declared static and therefore inaccessible in the TIFF -library.) - - -I'm including the four source files (tif_imgiter.h, tif_imgiter.c, -tif_pdsdirread.c, tif_pdsdirwrite.c) in case you want to take a look at -them. I can also send you some sample code that uses them if you like. -If you're interested in having them incorporated into the standard TIFF -library, I'd be happy to do that integration and clean up and document -the routines. (For example, I've already realized that instead of -limiting the SEP callback function to three bands (R,G,B) it should take -an array to enable the handling of n-banded multi-spectral data...) If -not, I'll just leave them as they are, since they work fine for us now. - -Holler if you have any questions. - --- Conrad -__________________________________________________________________ - Capt Conrad J. Poelman PL/WSAT (Phillips Laboratory) - 505-846-4347 3550 Aberdeen Ave SE - (FAX) 505-846-4374 Kirtland AFB, NM 87117-5776 - |