[gnuastro-devel] [task #14362] Automatic pixel value type on image manipulation

[Lee Kelvin]

URL:
  <http://savannah.gnu.org/task/?14362>

                 Summary: Automatic pixel value type on image manipulation
                 Project: GNU Astronomy Utilities
            Submitted by: leeskelvin
            Submitted on: Wed 08 Feb 2017 07:01:40 PM UTC
         Should Start On: Wed 08 Feb 2017 12:00:00 AM UTC
   Should be Finished on: Wed 08 Feb 2017 12:00:00 AM UTC
                Category: ImageWarp
                Priority: 5 - Normal
              Item Group: Enhancement
                  Status: None
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

ImageWarp currently does all of its internal processing in double precision
floating point and then saves the final array in the same type as the input.
The output may be optionally coerced to double type using the --doubletype
option.

I believe it would be desirable to have the output number type to be
dynamically decided upon by default, dependent upon the warpings which have
taken place. For example, when scaling a 1x1 pixel image containing the
integer '1' into a 2x2 region (--scale=2), the output should automatically be
saved to floating point accuracy with '0.25' in each pixel.

Ideally, the automatic output should be the least complex output possible
(i.e., producing the smallest output file size) whilst still retaining full
mathematical accuracy.

Changing the default behaviour of ImageWarp in this manner would allow for new
arguments on the command line such as --originaltype (to force maintain the
type of the original input) and also perhaps --singletype, --integertype,
--booleantype, in addition to the current --doubletype.

Best, 
Lee Kelvin





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