From 22f703cab05b7cd368f4de9e03991b7664dc5022 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=B6rg=20Frings-F=C3=BCrst?= Date: Mon, 1 Sep 2014 13:56:46 +0200 Subject: Initial import of argyll version 1.5.1-8 --- tiff/contrib/addtiffo/README | 142 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 tiff/contrib/addtiffo/README (limited to 'tiff/contrib/addtiffo/README') diff --git a/tiff/contrib/addtiffo/README b/tiff/contrib/addtiffo/README new file mode 100644 index 0000000..a6ca45f --- /dev/null +++ b/tiff/contrib/addtiffo/README @@ -0,0 +1,142 @@ + addtiffo 1.0 + ============ + +The addtiffo utility is used to add overview pyramids to an existing +TIFF or GeoTIFF file. Some applications can take advantage of these +overviews to accelerate overview display performance of large rasters. + +This release of addtiffo is primarily intended for compatibility testing +with applications, and to see if there is interest in a cleaner release +of the capability ... perhaps incorporation into the libtiff tools +distribution. + +Please feel free to contact me with questions, or problems. + +warmerda@home.com +http://home.gdal.org/~warmerda/ + + +Usage +----- + +Usage: addtiffo [-r {average/nearest} [-subifd] + tiff_filename [resolution_reductions] + +Example: + % addtiffo abc.tif 2 4 8 16 + +The numeric arguments are the list of reduction factors to +generate. In this example a 1/2, 1/4 1/8 and 1/16 + + + +Limitations +----------- + +See tif_overview.cpp for up to date details. + + o Currently only images with bits_per_sample of a multiple of eight + will work. + + o The code will attempt to use the same kind of compression, + photometric interpretation, and organization as the source image, but + it doesn't copy geotiff tags to the reduced resolution images. + + o Reduced resolution overviews for multi-sample files will currently + always be generated as PLANARCONFIG_SEPARATE. This could be fixed + reasonable easily if needed to improve compatibility with other + packages. Many don't properly support PLANARCONFIG_SEPARATE. + + o Overviews are always written as appended IFDs, rather than using the + ``tree of tree's'' approach using the SUBIFD tag. I wanted to implement + both, but it isn't currently easy to add a SUBIFD tag to an existing + main tiff IFD with libtiff. I hope to try this again later. + + +TIFF File Tags +-------------- + +The results of running addtiffo on a 1024x1024 tiled greyscale file +with the arguments ``2 4 8 16'' is to add four additional TIFF directories +appended on the file with the SUBFILETYPE flag to 0x1 indicating the extra +items are reduced resolution images. + +The tiffinfo output of such a file might look like this: + +TIFF Directory at offset 0x118008 + Image Width: 1024 Image Length: 1024 + Tile Width: 256 Tile Length: 112 + Bits/Sample: 8 + Compression Scheme: none + Photometric Interpretation: min-is-black + Samples/Pixel: 1 + Planar Configuration: single image plane +TIFF Directory at offset 0x15e1d2 + Subfile Type: reduced-resolution image (1 = 0x1) + Image Width: 512 Image Length: 512 + Tile Width: 256 Tile Length: 112 + Bits/Sample: 8 + Compression Scheme: none + Photometric Interpretation: min-is-black + Samples/Pixel: 1 + Planar Configuration: separate image planes +TIFF Directory at offset 0x1732b8 + Subfile Type: reduced-resolution image (1 = 0x1) + Image Width: 256 Image Length: 256 + Tile Width: 256 Tile Length: 112 + Bits/Sample: 8 + Compression Scheme: none + Photometric Interpretation: min-is-black + Samples/Pixel: 1 + Planar Configuration: separate image planes +TIFF Directory at offset 0x17a366 + Subfile Type: reduced-resolution image (1 = 0x1) + Image Width: 128 Image Length: 128 + Tile Width: 128 Tile Length: 112 + Bits/Sample: 8 + Compression Scheme: none + Photometric Interpretation: min-is-black + Samples/Pixel: 1 + Planar Configuration: separate image planes +TIFF Directory at offset 0x17b40c + Subfile Type: reduced-resolution image (1 = 0x1) + Image Width: 64 Image Length: 64 + Tile Width: 64 Tile Length: 64 + Bits/Sample: 8 + Compression Scheme: none + Photometric Interpretation: min-is-black + Samples/Pixel: 1 + Planar Configuration: separate image planes + + +Building +-------- + +You will need a C compiler. You will need to have libtiff already +built and installed. The provided Makefile should work on most Unix systems. +A similar file will be needed for Windows, but is not provided. + +The CFLAGS and LIBS macros in the Makefile will have to be updated to +point to the correct location of the libtiff include files, and library. + + +Credits +------- + + o Intergraph Corporation for partially funding the work. + + o Global Geomatics for partially funding reorganization of the overview + building ability as a separate utility. + + o Orrin Long, and Ed Grissom of Intergraph for explaining what needed to + be done. + + o Max Martinez of Erdas for his discussion of external overviews. + + o Atlantis Scientific who supported adding averaging, and some other + generalizations. + + o Frank Warmerdam for writing the bulk of the code. + + o Sam Leffler since this only exists because of his libtiff. + -- cgit v1.2.3