diff --git a/README.txt b/README.txt
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+++ b/README.txt
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Usage: fits2jpeg [options] <fits_file>
-
- Options are:
+ You need to specify a fits image file <fits_file> for this program to
+ work. Everything else is optional. A brief description of them are
+ listed below:
-h help
+ Prints out a usage-help message, much like this section.
-s <scale_type>
scale for output image, where <scale_type> can be:
normalize for linear histogram stretch
equalize for histogram equalization
+ -n
+ Negate the image
+
+ -q <value>
+ quality factor. Defines the jpeg encoding quality
+ Valid range: 0-100, default value: 100, which means
+ best quality and largest file-size.
+
+ -d <path/to/output/directory>
+ Write jpeg file to this specified directory. Will
+ create it if needed. Default is to write jpeg in the
+ same directory of fits image file
+
-r <min>:<max>
Clip output image to min-max range. Eg:
0:100 Use only values in the range 0-100
: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).
-
-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
+ Allowed range: 0.01 to 4.0
+ NOTE: Zooming will be carried out after all other
+ operations, before writing out jpeg image
fits2jpeg uses a bilinear interpolation based algorithm
to scale the image. Allowed range: 0.01 to 4.0
NOTE: Anything outside the allowed range will be clipped
+ to this range.
Output will be written to <fits_file_root>.jpg. For eg.,
Wild card entries allowed in <fits_file>. For eg: *.fits, m31*.fits
ngc???.fits etc.
- More examples:
+3.1 Examples:
+-------------
i. fits2jpeg -s log sirius.fits
+
will write out sirius.jpg, flux/intensity in log scale
ii. fits2jpeg -s sqroot *.fits
- Converts all fits files in the directory to jpegs, with
- square-root scaling of flux/intensity - Good for very
- high dynamic range images
+
+ Converts all fits files in the directory to jpegs, with square-root scaling
+ of flux/intensity - Good for very high dynamic range images
iii. fits2jpeg -n ngc4151.fits
+
Converts ngc4151.fits to ngc4151.jpg, negative image.
-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.
+ 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.
+
+ v. fits2jpeg -s equalize -r 200: -d/path/to/mydir NGS253*.fits
+
+ Reads all fits files in the present directory that matches the filename
+ patterm, performs a histogram equalization, drops pixel values below 200
+ and write out all the corresponding jpeg files to directory /path/to/mydir
+ Will create the destination directory tree if it does not exist.
3.1. Sequence of operations
v. Image zoom - magnify or shrink the image
vi. Write out jpeg file
+
3. DOCUMENTATION
----------------
An extensive coverage of how this program works along with line by line account