Next: 6.8 Create Shader Skeletons:
Up: 6. Command Line Options
Previous: 6.6 Image Information: imf_info
The image comparison utility imf_diff is started as
imf_diff [options] image1 image2
[outimage [outtype]]
The files image1 and image2 will be compared, and a
comparison summary is printed. If outimage is specified, a
difference image with a histogram is written to outimage. The
file format of this file is specified with outtype if present,
or taken from the file name extension if not. The following options
are supported:
- -a
Ignore alpha channel differences.
- -d
Display the difference image and the histogram in a window,
by starting the imf_disp program. This works with and
without an outimage on the command line.
- -e
Write an output image even if the compared input images match.
Normally the output image is written only if there are
differences.
- -f
Show differences in false colors, ranging from irrelevant
differences in blue, through significant differences in green,
red, and white.
- -g gamma
Perform gamma correction with the given gamma factor.
- -h
Print a brief option summary.
- -m thresh
Set the threshold in the range 0..255. Component differences
less than this threshold are ignored. The default is 3. The
main purpose is to discard differences introduced by dithering
(mental ray's dither option).
- -n
Do not add a histogram to the displayed or saved output image.
- -s
Magnify the differences such that the largest difference is
white and appears at the right edge of the histogram.
- -t thresh
The difference in percent that causes imf_diff to return
the return code 1 instead of 0. The default is 1. This is useful
for automated test suites.
- -u
Underlay image1 under the displayed or saved difference
image, at 1/10th brightness. This helps locating differences.
- -v
Verbose output prints messages showing what imf_copy
is doing, and a version banner.
The most common options are -f -u -d (also known as fear,
uncertainty, and doubt). Note that the sampling nature of mental ray
means that the true image is approximated with appropriately selected
samples until the desired image quality criteria are satisfied. This
approach ensures consistent quality but it does not necessarily create
images that are bit-for-bit identical if rendered under different
circumstances, such as different image task sizes, image task assignments
to threads or machines, different machines or different networks, or
different sampling options. Typically, differences shown in blue in the
color histogram are irrelevant.
Next: 6.8 Create Shader Skeletons:
Up: 6. Command Line Options
Previous: 6.6 Image Information: imf_info
Copyright 2002 by mental images