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.\" RCSid "$Id: ra_rgbe.1,v 1.4 2024/10/01 01:16:26 greg Exp $" |
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.TH RA_RGBE 1 1/23/98 RADIANCE |
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.SH NAME |
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ra_rgbe - convert between different RADIANCE picture types |
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.SH SYNOPSIS |
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.B ra_rgbe |
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[ |
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.B \-r |
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][ |
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.B "\-e +/-stops" |
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][ |
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.B \-f |
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][ |
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.B "\-n frameno" |
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] |
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[ |
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.B input |
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[ |
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.B outspec |
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] |
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] |
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.SH DESCRIPTION |
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.I Ra_rgbe |
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converts between RADIANCE run-length encoded and flat formats, and |
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separates concatanated animation frames produced by |
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.I rpict(1). |
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The |
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.I \-e |
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option specifies an exposure compensation in f-stops (powers of two). |
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Only integer stops are allowed, for efficiency. |
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By default, |
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.I ra_rgbe |
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produces a flat RADIANCE picture file from any type of RADIANCE |
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input picture. |
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The |
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.I \-r |
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option causes |
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.I ra_rgbe |
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to produce a run-length encoded file instead. |
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.PP |
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If the input file consists of multiple animation frames as produced by |
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.I rpict |
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with the |
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.I \-S |
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option, |
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.I ra_rgbe |
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will read each frame and write it to the output file created by calling |
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.I printf(3) |
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with the output specification and frame number as arguments. |
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If the output specification begins with an exclamation mark ('!'), |
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then this interpreted as a command spec., which is also run through |
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.I printf |
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with the frame number to get the final command. |
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This command must accept a Radiance picture on its standard input, |
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and may write results either to a file or to the standard output. |
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The |
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.I \-n |
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option may be used to select a specific frame for output, and |
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other frames in the input will be skipped. |
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Normally, all frames will be read and written. |
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.PP |
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.I Ra_rgbe |
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will report an error and exit if the target output file already exists, |
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unless the |
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.I \-f |
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option is given. |
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If the output file is missing, the standard output is used. |
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If the input file is missing or set to '-', the standard input is used. |
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.SH NOTES |
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The file format for RADIANCE pictures was changed between release |
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1.4 and release 2.0. |
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The older format can still be read by all the programs, but only |
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the newer format is produced. |
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This newer format cannot be read by RADIANCE software prior to |
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release 2.0. |
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.PP |
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.I Ra_rgbe |
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provides some downward compatibility by producing files that can |
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be read by older RADIANCE software. |
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The resultant files are also easier to manipulate with programs |
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designed to read raw raster data. |
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.PP |
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The other use for |
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.I ra_rgbe |
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is as a quicker way to adjust the exposure of a RADIANCE picture than |
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.I pfilt(1), |
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since |
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.I ra_rgbe |
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only allows integer f-stop changes. |
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In this mode, |
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.I ra_rgbe |
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should be used with the |
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.I \-r |
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option. |
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.SH NOTES |
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Hyperspectral Radiance pictures (.hsr files) are |
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converted to approximate RGBE pixels. |
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However, the colors may not be very accurate. |
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Pass the HSR picture through |
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.I rcomb(1) |
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or |
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.I ra_xyze(1) |
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first if greater color fidelity is required. |
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.SH AUTHOR |
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Greg Ward |
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.SH ACKNOWLEDGEMENT |
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Work on this program was initiated and sponsored by the LESO |
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group at EPFL in Switzerland. |
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.SH "SEE ALSO" |
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dctimestep(1), pfilt(1), printf(1), pvsum(1), ra_xyze(1), rcomb(1), rpict(1) |
