www.schorsch.com
| ra_tiff - convert RADIANCE picture to/from a TIFF color or greyscale image |
|
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|- ] |
| 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. |
| The -b option can be used to specify an 8-bit greyscale TIFF output file. The type of input file is determined automatically. |
| 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. |
| The -e option specifies an exposure compensation in f-stops (powers of two). Only integer stops are allowed, for efficiency. |
| 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. |
| To convert a Radiance picture to SGILOG-compressed TIFF format: |
| ra_tiff -L scene1.pic scene1.tif |
| To later convert this image back into Radiance and display using human visibility tone-mapping: |
|
ra_tiff -r scene1.tif scene1.pic ximage -e human scene1.pic |
|
Greg Ward Larson Sam Leffler |
| 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. |
|
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. |
| pfilt(1), ra_bn(1), ra_ppm(1), ra_pr(1), ra_pr24(1), ra_t8(1), ra_t16(1), ximage(1) |