Hi Darragh, Here is the man page, which you should have downloaded with the binary. Was it not in there? Sorry the binary is giving you troubles. I've not found a way to compile for all Linux machines. They generally expect you to compile things yourself, and I'm not distributing source code in this case. -Greg |
hdrgen
Create
a high dynamic-range image from multiple exposures of a static scene. The input files may be JPEG or TIFF, but
must be 24-bit RGB (trichromatic) images.
The output is your choice of
a Radiance HDR picture or a 32-bit LogLuv TIFF image.
The syntax of the hdrgen command is: hdrgen –o out_file
[–r cam.rsp] [–m cachesiz] [–a] [–e] [–s stonits1]
image1 [–s stonits2] image2 … As many
exposures may be given as necessary, and should ideally be spaced within two
f–stops of each other. The
brightest exposure should have no black pixels, and the darkest exposure should
have no white pixels, but there is little point in extending beyond these
limits, which may cause problems in determining the camera response function. The order of options and input files is
unimportant, with the exception of the –s option, which must preceed the corresponding exposure. Following is an explanation of the
options and their meanings: –o out_file -F Toggle
output file overwrite switch (defaults to “false”). -k var_file -q quality –r cam.rsp -c CS –m cachesiz –a Toggle
automatic exposure alignment. The
default value is “on,” so giving this option one time switches it off. The alignment algorithm examines
neighboring exposures and finds the pixel offset in x and y that minimizes the
difference in the two images. It
may be necessary to switch this option off when dealing with very dark or very
bright exposures taken in a tripod-stabilized sequence. –e Toggle
exposure adjustment. Normally “on,”
exposure adjustment fine-tunes the scale difference between adjacent images to
account for slight inaccuracies in the aperture or speed settings of the
camera. -x Toggle
over- and under-exposed image removal.
Normally “off,” this option causes unnecessary exposures that are too
light or too dark to contribute useful information to be automatically ignored. –f Toggle
lens flare removal. Normally,
“off,” this option is designed to reduce the scattered light from a camera’s
lens and aperture, which results in a slightly fogged appearance in high
dynamic-range images. -g Toggle
ghost removal. Normally “off,” this
option attempts to remove moving or changing objects in a scene, which cause
ghosts in the combined output. –s stonits Diagnostics
The
primary failure mode for this algorithm is the one mentioned in the description
of the –r option, when the exposures contain too little information to
solve for the camera response function.
The best solution to this problem is to take off the exposures that are
very light and very dark, or to use a different sequence of images to generate
a response file. This file may then
be used to combine the entire set of images, since the program no longer needs
to solve for the responses. Most of the other diagnostics you will encounter are
“warnings,” which means that the final image will be written, but may have
problems. In particular, when the
alignment algorithm fails on a hand-held sequence, some ghosting may be visible
on high contrast edges in the output.
Using the –a option to turn off automatic alignment will eliminate
the warning, but unless the sequence was taken on a very stable tripod, the
results will usually be worse rather than better. Example
To
combine all JPEG images matching a given wildcard and put into a LogLuv TIFF: hdrgen P13351?.JPG –o testimg.tif Author
This
software was written by Greg Ward of Exponent Corporation. Send comments or questions to [email protected] or [email protected]. References
Tomoo Mitsunaga
and Shree Nayar, “Radiometric
Self-Calibration,” Proceedings of IEEE Conference on Computer Vision and
Pattern Recognition, June, 1999. Greg
Ward, “LogLuv encoding for full-gamut, high-dynamic range images ,”
Journal of Graphics Tools, 3(1):15-31 1998. Greg
Ward, High
Dynamic Range Images, web page. Paul Debevec, web
page. |
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