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
correspond to units of candelas/meter^2. Otherwise, the RGB
values should be in spectral watts/steradian/meter^2.
Specifying +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
conversion 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
foreign 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
Radiance 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.
bottom 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
determines 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.hdr
pflip -v flipped.hdr > final.hdr
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)