diff --git a/README.txt b/README.txt
--- a/README.txt
+++ b/README.txt
0. FEATURES
-----------
-fits2jpeg is a tiny program to read FITS Images and convert them
-to jpeg, which is more popular. This software supports various
-type of intensity scaling and image enhancements. fits2jpeg do not
-support coordinate axes overlay. fits2jpeg supports batch mode
-operations - for instance, converting several fits files to jpeg
-at once.
+fits2jpeg is a tiny program to read FITS Images and convert them to jpeg, which
+is more popular. This software supports various type of intensity scaling and
+image enhancements. fits2jpeg do not support coordinate axes overlay. fits2jpeg
+supports batch mode operations - for instance, converting several fits files to
+jpeg at once.
1. BUILD/INSTALL
http://heasarc.gsfc.nasa.gov/docs/software/fitsio/fitsio.html
b) JPEGLIB
- jpeg library and headers. libjpeg is installed by default on most
- platforms, but we need the header files too. Once you have cfitsio
- and jpeglib installed, you may proceed with compiling jpeg2fits.
+ jpeg library and headers. libjpeg is installed by default on most platforms,
+ but we need the header files too. Once you have cfitsio and jpeglib
+ installed, you may proceed with compiling jpeg2fits.
+
Follow these 4 steps:
2. Type `make' to compile the package.
3. Type `make install' to install the programs and any data files and
- documentation. By default, the binary is copied to /usr/local/bin.
- You may change this destination by passing on the following
- argument to configure:
+ documentation. By default, the binary is copied to /usr/local/bin. You may
+ change this destination by passing on the following argument to configure:
--prefix=/your/chosen/destination
Which would result in the binary in /your/chosen/destination/bin
You may need to ensure that in $PATH to run the program.
- 4. You can remove the program binaries and object files from the
- source code directory by typing `make clean'.
+ 4. You can remove the program binaries and object files from the source code
+ directory by typing `make clean'.
-You may read more about configure script and others in the accompanying
-file named `INSTALL.txt'.
+You may read more about configure script and others in the accompanying file
+named `INSTALL.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.
- -e <operation>
- Imaghe enhancement operations. Valid arguments are:
+ -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).
- equalize perform histogram equalization
- normalize perform a linear contrast stretch
- (use cutoffs at 1% and 99% for image data)
+ -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
+
+ 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
Output will be written to <fits_file_root>.jpg. For eg.,
writes output to jpeg file 30dor.jpg
- Wild card entries allowed in <fits_file>. For eg: *.fits,
- m31*.fits ngc???.fits etc.
+ Wild card entries allowed in <fits_file>. For eg: *.fits, m31*.fits
+ ngc???.fits etc.
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.
+
+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.
-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 :)
+3.1. Sequence of operations
+---------------------------
+Here is the sequence of operations, after reading the fits file:
+
+ i. clip the image to user specified pixel limits, if it was requested
+ ii. Squeeze image pixel values to jpeg limits (0 - 255)
+ iii. image scaling function, default being linear pixel scale
+ iv. Negate the image, if requested
+ 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 of the happenings within the code, are dealt with
-in the user manual, which is yet to be written :(
+An extensive coverage of how this program works along with line by line account
+of the happenings within the code, are dealt with in the user manual, which is
+yet to be written :(
4. LICENSE: GPL [See the file COPYING.txt for details]
5. DISCLAIMER
-------------
-You may encounter bugs in this software. If you do, please
-report them. Your bug reports are valuable contributions,
-since they allow us to notice and fix problems on
-machines/platforms we don't have, and/or remained un-noticed.
+You may encounter bugs in this software. If you do, please report them. Your bug
+reports are valuable contributions, since they allow us to notice and fix
+problems on machines/platforms we don't have, and/or remained un-noticed.
6. REPORTING BUGS
Either way, please include as many details as possible.
+
-----------------------------------------------------------
Reks, 28 June 2012 <reks_at_iiap.res.in>
- Last modified: 28 June 2012
+ Last modified: 10 July 2012