145 lines
4.6 KiB
Groff
145 lines
4.6 KiB
Groff
.TH IM_TIFF 3 "6 June 1994"
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.SH NAME
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im_tiff2vips, im_tiff2vips \- convert TIFF images to and from VIPS format
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.SH SYNOPSIS
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#include <vips/vips.h>
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int im_tiff2vips( const char *filename, IMAGE *out )
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int im_vips2tiff( IMAGE *in, const char *filename )
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.SH DESCRIPTION
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.B im_tiff2vips(3)
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reads the tiff image in filename, and writes the image out
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in VIPS format. It is a full baseline TIFF 6 reader, with extensions for
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tiled images, multipage images, LAB colour space, pyramidal images and
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JPEG compression.
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You can embed options in the filename. They have the form:
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filename.tif:<page-number>
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.B page-number
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lets you read a particular page out of a multipage TIFF file. For
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example:
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"fred.tif:12"
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will read page 12 (numbering from page zero) from the TIFF image.
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.B im_vips2tiff(3)
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reads the image in and writes a TIFF file to the specified
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filename. The filename may include an optional mode string, following a ':'
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character. For example, "fred.tif" would write a default TIFF file (flat,
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strips, no compression). Writing to "fred.tif:deflate,tile:64x64" would write a
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ZIP-coded image, split into 64 by 64 pixel tiles.
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The mode string has the following syntax:
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<compression>,<layout>,<multi-res>,<format>,<resolution>,<icc>
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where <compression> is one of:
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"none" - no compression
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"jpeg" - JPEG compression
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"deflate" - ZIP (deflate) compression
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"packbits" - TIFF packbits compression
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"ccittfax4" - CCITT Group 4 fax encoding
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"lzw" - Lempel-Ziv compression
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"jpeg" compression can be followed by a ":" character and a JPEG quality
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level; "lzw" and "deflate" can be followed by a ":" and predictor value. The
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default compression type is "none", the default JPEG quality factor is 75.
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Predictor is not set by default. There are three predictor values recognised
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at the moment (2007, July): 1 is no prediction, 2 is a horizontal differencing
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and 3 is a floating point predictor. Refer to the libtiff specifications for
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further discussion of various predictors. In short, predictor helps to better
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compress image, especially in case of digital photos or scanned images and bit
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depths > 8. Try it to find whether it works for your images.
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JPEG compression is a good lossy compressor for photographs, packbits is good
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for 1-bit images, and deflate is the best lossless compression TIFF can do.
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LZW has patent problems and is no longer recommended.
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<layout> is one of:
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"strip" - strip layout
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"tile" - tiled layout
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"tile" layout can be followed by a ":" character and the horizontal and
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vertical tile size, separated by a "x" character. The default layout is
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"strip", and the default tile size is 128 by 128 pixels.
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<multi-res> is one of:
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"flat" - single image
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"pyramid" - many images arranged in a pyramid
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The default multi-res mode is "flat".
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<format> is one of:
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"manybit" - don't bit-reduce images
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"onebit" - one band 8 bit images are saved as 1 bit
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The default format is "multibit".
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<resolution> is one of:
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"res_cm" - output resolution unit is pixels per centimetre
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"res_inch" - output resolution unit is pixels per inch
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The default resolution unit is taken from the header field "resolution-unit"
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(IM_META_RESOLUTION_UNIT in C). If this field is not set, then VIPS defaults
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to cm.
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This may be overridden by the <resolution> option. The unit can optionally
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be followed by a ":" character and the horizontal and vertical resolution,
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separated by a "x" character. You can have a single number with no "x" and
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set the horizontal and vertical resolutions together. The default unit is
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cm, and the default resolution is taken from the VIPS header.
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<icc> is the filename of an ICC profile to embed in the TIFF file
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The TIFF reader and writer are based on Sam Leffler's TIFF library, and the IJG
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JPEG coder.
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.SH EXAMPLES
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The call:
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im_vips2tiff fred.v fred.tif
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Writes a striped, uncompressed TIFF image. Almost anything should be able to
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read this.
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im_vips2tiff fred.v fred.tif:jpeg,tile,pyramid
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Writes a tiled JPEG pyramid image. Although VIPS tries to follow the TIFF
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specification carefully, you may have trouble reading this on any system other
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than VIPS.
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im_vips2tiff fred.v fred.tif:jpeg:25,tile:64x64
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Writes a highly compressed JPEG image, with a tile size of 64 by 64 pixels.
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im_vips2tiff fred.v fred.tif:,tile
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Writes an uncompressed tiled image.
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im_vips2tiff fred.v fred.tif:packbits,tile,,onebit
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Writes a tiled one bit TIFF image (provided fred.v is a one band 8 bit image)
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compressed with packbits.
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im_vips2tiff fred.v fred.tif:,,,,res_inch:300
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Writes fred.v as a tiff file, with the resolution in the tiff header set to
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300 dpi.
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.SH SEE ALSO
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im_open(3)
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.SH COPYRIGHT
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Hey, you want this? You have it!
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