diff --git a/README.txt b/README.txt
--- a/README.txt
+++ b/README.txt
2.USAGE
-------
- fits2jpeg [options] <fits_file>
+ Usage: fits2jpeg [options] <fits_file>
+
+ Options are:
- Options are:
-h help
-s <scale_type>
- scale for output image intensity. Valid arguments are:
-
- linear for linear scaling, default
+ scale for output image, where <scale_type> can be:
+ linear Linear scale, default
sqroot for square root scale
square for quadratic scale
cubic for cubic scale
log for log scale
+ normalize for linear histogram stretch
+ equalize for histogram equalization
+
+ -r <min>:<max>
+ Clip output image to min-max range. Eg:
+ 0:100 Use only values in the range 0-100
+ 100:0 Same as above, but negative image
+ :10 Clip everything above 10
+ 10: Clip everything below 10
+
+ -n
+ Negate the image.
+
+ -q <value>
+ jpeg quality factor. Defines the jpeg encoding quality
+ Valid range: 0-100, default value: 100, which is for
+ best quality (and largest file size).
- -e <operation>
- Imaghe enhancement operations. Valid arguments are:
+ -z <zoomfactor>
+ Resize/Scale output image by <zoomfactor>. Eg:
+ 0.5 Shrink output to half of input
+ 2.0 Magnify output to double the size
- equalize perform histogram equalization
- normalize perform a linear contrast stretch
- (use cutoffs at 1% and 99% for image data)
Output will be written to <fits_file_root>.jpg. For eg.,
More examples:
- i. fits2jpeg -s cubic sirius.fits
+ i. fits2jpeg -s log sirius.fits
will write out sirius.jpg, flux/intensity in log scale
ii. fits2jpeg -s sqroot *.fits
square-root scaling of flux/intensity - Good for very
high dynamic range images
-iii. fits2jpeg -e normalize ngc4151.fits
- Converts ngc4151.fits to ngc4151.jpg, contrast stretched.
+iii. fits2jpeg -n ngc4151.fits
+ Converts ngc4151.fits to ngc4151.jpg, negative image.
-NOTE: You can perform scaling + enhancing on an image. Scaling will
- always be performed first. In most cases combining these two
- would lead to un-usable images :)
+iv. fits2jpeg -s square -n -r 10:2000 m31.fits
+ Write out m31.jpg, after square scaling of flux/intensity,
+ negate image and clip pixel values in the range 10 to 2000
+ units.
3. DOCUMENTATION
-----------------------------------------------------------
Reks, 28 June 2012 <reks_at_iiap.res.in>
- Last modified: 28 June 2012
+ Last modified: 10 July 2012