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Add README.utils

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1 parent b83086e commit c193a711ff3e6788e6372fc9dd824a28dc77df5d @snogglethorpe committed Jan 8, 2012
Showing with 203 additions and 1 deletion.
  1. +2 −1 Makefile.am
  2. +3 −0 README
  3. +198 −0 README.utils
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3 Makefile.am
@@ -48,7 +48,8 @@ noinst_LIBRARIES = libsnogcli.a libsnogcolor.a libsnogimage.a \
# Various files to include in distribution not covered by automatic rules
#
EXTRA_DIST = \
- README README.building README.usage README.issues \
+ README README.building README.issues README.usage \
+ README.utils \
snogray.lua \
load-obj.lua load-ug.lua load-stl.lua load-nff.lua \
snograw.swg vector.swg val-table.swg \
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3 README
@@ -13,6 +13,9 @@ Snogray renderer
* For discussion of some snogray usage issues, see the file "README.issues"
+ * For information on other utility programs included with snogray,
+ see the file "README.utils"
+
Snogray development goals:
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198 README.utils
@@ -0,0 +1,198 @@
+Snogray utilities
+
+This file documents the various utility programs included with
+snogray.
+
+
+snogcvt
+
+ snogcvt is a simple image-conversion program. It can convert
+ between different image formats, do image downscaling and
+ upscaling, adjust exposure/contrast, etc.
+
+ Basic usage:
+
+ snogcvt [OPTION...] INPUT_IMAGE_FILE OUTPUT_IMAGE_FILE
+
+ Copy the contents of INPUT_IMAGE_FILE to OUTPUT_IMAGE_FILE,
+ incorporating any modifications resulting from command-line
+ options.
+
+ Options:
+
+ [See "COMMON COMMAND-LINE IMAGE OPTIONS" below for options.]
+
+
+snogbloom
+
+ snogbloom adds "veiling glare" to an HDR input image. Normally
+ this is used when converting to a LDR output format (snogbloom
+ itself can do the conversion), and can make LDR images with very
+ bright areas look much more realistic.
+
+ Basic usage:
+
+ snogbloom [OPTION...] INPUT_IMAGE_FILE OUTPUT_IMAGE_FILE
+
+ Copy the contents of INPUT_IMAGE_FILE to OUTPUT_IMAGE_FILE
+ along with added glare (and any other modifications resulting
+ from command-line options).
+
+ Options:
+
+ -f DEG
+ --field-of-view=DEG
+
+ Set the image field-of-view (of the image diagonal) to be DEG
+ degrees. As the intensity of the glare effect is dependent on
+ angular deviation, snogbloom needs to know the angular size of
+ the input image. The default is 46.8 degrees, corresponding
+ to a "typical" angle-of-view.
+
+ -g
+ --glare-only
+
+ Normally snogbloom outputs an image which is the sum of the
+ input image and added glare. The -g/--glare-only option causes
+ it to output only the glare.
+
+ --threshold=INTENS
+
+ snogbloom only adds glare for image intensities above a certain
+ threshold, which maybe be set with the --threshold=INTENS
+ option. By default this is 1, meaning that "normal"
+ intensities (those which are perfectly representable in
+ low-dynamic-range image formats) do not result in glare.
+
+ [See "COMMON COMMAND-LINE IMAGE OPTIONS" below for more options.]
+
+
+snogdiff
+
+ snogdiff computes the difference between two input images, which is
+ useful for analyzing subtle changes.
+
+ Basic usage:
+
+ snogdiff [OPTION...] IMAGE_FILE_1 IMAGE_FILE_2 DIFF_IMAGE_FILE
+
+ Compute the difference between IMAGE_FILE_1 and IMAGE_FILE_2
+ and output it to DIFF_IMAGE_FILE. Any image modifications
+ resulting from command-line options are performed on the
+ resulting "difference image" (for instance, a "-e+5" option
+ may be used to intensify the output image, making small
+ differences easier to see).
+
+ Options:
+
+ [See "COMMON COMMAND-LINE IMAGE OPTIONS" below for options.]
+
+
+sampleimg
+
+ sampleimg produces a "sampled" version of an input image.
+
+ Basic usage:
+
+ sampleimg [OPTION...] INPUT_IMAGE_FILE OUTPUT_IMAGE_FILE
+
+ Sample the image in INPUT_IMAGE_FILE, and output a new image
+ OUTPUT_IMAGE_FILE visualizing the resulting sample
+ distribution.
+
+ Options:
+
+ -m METH
+ --method=METH
+
+ Use sampling method METH, which may be one of:
+
+ radical-inverse, radical -- A "radical inverse"
+ quasi-random sequence
+
+ random, rand -- A sequence of uniform pseudo-random
+ numbers
+
+ stratified, strat -- A stratified sequence of
+ pseudo-random numbers
+
+ The default is "radical-inverse".
+
+ -n NUM
+ --samples=NUM
+
+ Use NUM samples. The default is 1000000.
+
+ -v VAL
+ --value=VAL
+
+ Give each sample an intensity of VAL in the output image.
+ A smaller intensity with more samples yields a more "subtle"
+ result. The default is 0.1, which works well the default
+ number of samples.
+
+
+COMMON COMMAND-LINE IMAGE OPTIONS
+
+ Almost all image-manipulation programs included in the snogray
+ distribution support a common set of command-line options. These
+ are described below.
+
+ -s WIDTHxHEIGHT
+ --size=WIDTHxHEIGHT
+ -s WIDTH
+ --size=WIDTH
+
+ Set the output -image size to WIDTH by HEIGHT pixels.
+
+ If the "xHEIGHT" portion of the value is omitted, then WIDTH
+ is divided by the default aspect ratio to get the height.
+
+ ["x" is a literal character x, WIDTH and HEIGHT should be
+ replaced by numbers; e.g.: --size=640x480 ]
+
+ -e EXPOSURE
+ --exposure=EXPOSURE
+
+ Modify the brightness/contrast of the output image.
+
+ EXPOSURE can have one of the following forms:
+
+ +STOPS Make the output image 2^STOPS times brighter -STOPS
+ Make the output image 2^STOPS times dimmer *SCALE Make the
+ output image SCALE times brighter /SCALE Make the output
+ image SCALE times dimmer
+
+ ^POWER Raise each output pixel to the POWER power; this
+ modifies the contrast of the output. Use a
+ positive value of POWER for higher contrast, and
+ a negative value of POWER for lower contrast.
+
+ Brightness and contrast modifications may be combined, e.g.,
+ "+4^2" first multiplies each output pixel by 2^4 (16), and
+ then raises the result to the 2nd power. Note that when used
+ together, there's a great deal of interaction between these
+ settings, so it may be necessary to adjust one to compensate
+ for the effect of the other (e.g.,
+
+ Increase or decrease exposure by STOPS f-stops
+
+ -F FILTER[/PARAM=VAL...] -filter=FILTER[/PARAM=VAL...]
+
+ Set the filter used for the output image to FILTER, and
+ optionally change some filter parameters.
+
+ Possible values of FILTER include "mitchell", "gauss", and
+ "box" (default "mitchell").
+
+ The set of filter parameters vary depending on the filter, but
+ some include:
+
+ "width" -- the width of the filter, used by most filters
+ "a", "b" -- parameters for the "mitchell" filter "alpha" --
+ parameter for the "gauss" filter
+
+ --no-preclamp
+
+ Do not use "image preclamping" when writing to a
+ low-dynamic-range output file.

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