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ra_tiff (1)
NAME
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ra_tiff - convert RADIANCE picture to/from a TIFF color or greyscale image |
SYNOPSIS
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ra_tiff [ -z|-L|-l ][ -b ][ -e
+/-stops ][ -g gamma ] { in.pic|- }
out.tif
ra_tiff -r [ -x ][ -g gamma ][ -e
+/-stops ] in.tif [ out.pic|-
] |
DESCRIPTION
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Ra_tiff converts between RADIANCE and TIFF image
formats. The -g option specifies the exponent used in
gamma correction; the default value is 2.2, which is the
recommended value for TIFF images. |
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The -b option can be used to specify an 8-bit
greyscale TIFF output file. The type of input file is
determined automatically. |
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The -z option will result in LZW compression of the
TIFF output file. The -L option specifies SGILOG
compression, which is recommended to capture the full
dynamic range of the Radiance picture. However, since many
TIFF readers do not yet support this format, use this option
under advisement. The -l option specifies SGILOG24
compressed output, which has slightly less dynamic range
than SGILOG, but may be smaller in some cases. (It may also
be larger in some cases.) Decompression is automatically
determined for TIFF input. |
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The -e option specifies an exposure compensation in
f-stops (powers of two). Only integer stops are allowed, for
efficiency. |
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The -r option invokes a reverse conversion, from a
TIFF image to a RADIANCE picture. The RADIANCE picture file
can be taken from the standard input or sent to the standard
output by using a hyphen ('-') in place of the file name,
but the TIFF image must be to or from a file. The -x
option can be used to specify an XYZE Radiance output file,
rather than the default RGBE. |
EXAMPLES
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To convert a Radiance picture to SGILOG-compressed TIFF
format: |
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ra_tiff -L scene1.pic scene1.tif |
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To later convert this image back into Radiance and display
using human visibility tone-mapping: |
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ra_tiff -r scene1.tif scene1.pic
ximage -e human scene1.pic |
AUTHOR
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Greg Ward Larson
Sam Leffler |
ACKNOWLEDGEMENT
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Work on this program was initiated and sponsored by the LESO
group at EPFL in Switzerland. Additions for the SGILOG data
encoding were sponsored by Silicon Graphics,
Inc. |
BUGS
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Many TIFF file subtypes are not supported.
A gamma value other than 2.2 is not properly recorded or
understood if recorded in the TIFF file. |
SEE ALSO
|
