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.TH RA_BMP 1 3/25/04 RADIANCE
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.SH NAME
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ra_bmp - convert RADIANCE picture to/from Windows BMP image
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.SH SYNOPSIS
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.B ra_bmp
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[
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.B \-b
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][
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.B "\-g gamma"
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][
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.B "\-e spec"
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][
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.B "-p xr yr xg yg xb yb xw yw"
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]
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[
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[
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.B input|-
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[
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.B output
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]
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]
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.br
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.B ra_bmp
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.B \-r
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[
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.B "\-g gamma"
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][
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.B "\-e +/-stops"
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]
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[
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[
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.B input|-
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[
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.B output
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]
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]
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.SH DESCRIPTION
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.I Ra_bmp
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converts between RADIANCE and a Windows BMP image.
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During forward conversion, the
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.I \-b
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option produces 8-bit grayscale output rather than 24-bit RGB.
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The
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.I \-g
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option specifies the exponent used in monitor gamma correction;
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the default value is 2.2.
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The
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.I \-e
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option specifies a tone-mapping method or exposure compensation.
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If the argument is one of the special words "auto", "human", or "linear",
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the image will be tone-mapped with histogram adjustment,
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human vision simulation, or an averaged linear exposure,
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respectively.
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(These words may be abbreviated by one or more letters.)\0
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Otherwise, the exposure specification is interpreted as a
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linear compensation value in integer f-stops, which must
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be proceeded by a '+' or '-'.
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The CRT color output primaries may be specified with the
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.I \-p
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option.
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.PP
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The
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.I \-r
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option invokes a reverse conversion, from a Windows BMP image
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to a RADIANCE picture.
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Tone-mapping and monitor primaries are not
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supported for reverse conversion.
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.PP
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.I Ra_bmp
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can accept 16-bit or color-mapped BMP files on input,
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but cannot not produce them on output.
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.PP
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A hyphen ('-') may be specified to indicate standard input for
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either forward or reverse conversion so that an output file may be
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specified.
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If the BMP input is taken from the standard input or sent to the
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standard output without tone-mapping, then the scanlines may
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be reversed from their usual ordering.
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Reversed scanlines sometimes causes difficulties for programs attempting
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to interpret the resulting RADIANCE picture or BMP image, which
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may be rejected or displayed inverted.
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.SH NOTES
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Hyperspectral Radiance pictures (.hsr files) are
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converted to approximate RGB 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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first if greater color fidelity is required.
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.SH AUTHOR
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Greg Ward
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.SH "SEE ALSO"
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pfilt(1), ra_ppm(1), ra_pr(1), ra_pr24(1), ra_t8(1), ra_t16(1),
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ra_tiff(1), rcomb(1), ximage(1)
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