Radiance pvalue program
PVALUE(1) PVALUE(1)
NAME
pvalue - convert RADIANCE picture to/from alternate formats
SYNOPSIS
pvalue [ options ] [ file ]
pvalue -r [ options ] [ file1 [ file2 file3 ] ]
DESCRIPTION
Pvalue converts the pixels of a RADIANCE picture to or from another
format. In the default mode, pixels are sent to the standard output,
one per line, in the following ascii format:
xpos ypos red green blue
If no file is given, the standard input is read.
The reverse conversion option (-r) may be used with a single input file
or when reading from the standard input, but if the second form is used
with three separate input files, the three primaries are presumed to be
separated in these files.
-u Print only unique values in the output, skipping runs of
equal pixels. Specifying +u turns this option off, which is
the default.
-o Print original values, before exposure compensation. If the
input file is in XYZE format, the Y (green) channel will cor-
respond to units of candelas/meter^2. Otherwise, the RGB
values should be in spectral watts/steradian/meter^2. Speci-
fying +o uses final exposed values, which is the default.
-h Do not print header. Specifying +h causes the header to be
printed, which is the default.
-H Do not print the resolution string. (See also the -r option
below.) Specifying an input resolution for reverse conver-
sion also turns this option off. Specifying +H causes the
resolution string to be printed, which is the default.
-s nbytes Skip the specified number of bytes on the input header. This
option is useful for skipping unintelligible headers in for-
eign file formats. (Does not work when reading from standard
input.)
-e exposure
Adjust the exposure by the amount specified. If the exposure
is being given as a conversion factor, use +e instead, so an
EXPOSURE line will not be recorded in the header (if any).
-g gamma Set gamma correction for conversion. When converting from a
RADIANCE picture to another format, the inverse gamma is
applied to correct for monitor response. When converting to
a RADIANCE picture (-r option), the gamma is applied directly
to recover the linear values. By default, gamma is set to
1.0, meaning no gamma correction is performed.
-d Data only, do not print x and y pixel position.
-da Same as -d.
-di Print ascii integer values from 0 to 255+. If +di is given,
the integer values will be preceded by the x and y pixel
locations.
-db Output binary byte values from 0 to 255.
-dw Output binary 16-bit words from 0 to 65535.
-dW Output binary 16-bit words from 0 to 65535, byte-swapped.
-df Output binary float values.
-dF Output byte-swapped binary float values.
-dd Output binary double values.
-dD Output byte-swapped binary double values.
-R Reverse ordering of colors so that the output is blue then
green then red. The default ordering (specified with +R) is
red then green then blue.
-n The RGB values are non-interleaved, meaning that all the red,
green and blue data are stored together in separate chunks.
Interleaving may be turned on with the +n option, which is
the default.
-b Print brightness values rather than RGB. Specifying +b turns
this option off, which is the default.
-pP Put out only the primary P, where P is one of upper or lower
case 'R', 'G' or 'B' for red, green or blue, respectively.
This option may be used to separate the Radiance primaries
into three files with three separate runs of pvalue, or only
one file when only one primary is needed. Note that there is
no space between this option and its argument.
-r Perform reverse conversion. Input is in the format given by
the other options. The x and y resolution must be specified
on the command line, unless the image file contains a Radi-
ance resolution string at the beginning (see -H option above
and -y option below). Specifying +r converts from a Radiance
picture to other values, which is the default.
-y res Set the output y resolution to res. If +y is specified, then
the scanlines are assumed to be in increasing order (ie. bot-
tom to top). The default value for this option is 0, which
means that the picture size and scanline order must appear as
the first line after the header (if any) in the input file.
Either an upper or lower case 'Y' may be used for this
option. Since Radiance files always contain such a line,
this option has no effect for forward conversions.
+x res Set the output x resolution to res. If -x is specified, then
the scanlines are assumed to be in decreasing order (ie.
right to left). The ordering of the -y and +x options deter-
mines whether the scanlines are sorted along x or along y.
Most Radiance pictures are sorted top to bottom, then left to
right. This corresponds to a specification of the form "-y
yres +x xres". Either an upper or lower case 'X' may be used
for this option. Like the -y option, -x options have no
effect for forward conversions.
EXAMPLE
To look at the original, unique pixels in picture:
pvalue -o -u picture | more
To convert from a 512x400 8-bit greyscale image in bottom to top, left
to right scanline ordering:
pvalue -r -db -b -h +y 400 +x 512 input.im > flipped.pic
pflip -v flipped.pic > final.pic
AUTHOR
Greg Ward
BUGS
The -r option does not work with the -u option. Also, input pixel
locations are ignored during a reverse conversion, so this information
is not used in determining the scanline ordering or picture size.
SEE ALSO
getinfo(1), pcompos(1), pfilt(1), pflip(1), protate(1), rpict(1),
rtrace(1), rvu(1)
RADIANCE 1/15/99 PVALUE(1)
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