X-Git-Url: https://cads.iiap.res.in/gitview/?p=fits2jpeg.git;a=blobdiff_plain;f=README.txt;h=c5f5ca1a4aed9fe1f81bef21f5ee1f40219a24c9;hp=df79f4a36c9bbda27f4be161ee209f05d12a4b9d;hb=c217f20a424f31d11946263980a8f14ca7a79a0e;hpb=60d065b23a2bdd48da5b8ef3ce591b7b0313c979

diff --git a/README.txt b/README.txt
index df79f4a..c5f5ca1 100644
--- a/README.txt
+++ b/README.txt
@@ -6,12 +6,11 @@ README file for CADS/UVS fits2jpeg software
 
 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
@@ -26,9 +25,10 @@ Pre-requisites:
     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:
 
 
@@ -61,20 +61,19 @@ Pre-requisites:
   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
@@ -116,6 +115,9 @@ file named `INSTALL.txt'.
          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.,
 
@@ -123,8 +125,8 @@ file named `INSTALL.txt'.
 
   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:
 
@@ -145,11 +147,22 @@ iv.  fits2jpeg -s square -n -r 10:2000 m31.fits
      units.
 
 
+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]
@@ -158,10 +171,9 @@ in the user manual, which is yet to be written :(
 
 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
@@ -174,6 +186,7 @@ If you are too lazy, drop in an email to: cads_AT_iiap.res.in
 
 Either way, please include as many details as possible.
 
+
 -----------------------------------------------------------
 Reks, 28 June 2012 <reks_at_iiap.res.in>
       Last modified: 10 July 2012