[ncl-talk] Raster image discrepancies between versions 6.1.2 and 6.2.x

[David Brown]

Hi Andrea,
I do see the small but noticeable differences you are talking about,
and I am not sure why either. If you can send us your script and data,
we can try to figure out the cause. For info on uploading files, see
the page: http://www.ncl.ucar.edu/report_bug.shtml
Be sure to let me know (offline) the names of the files you upload.
Thanks,
 -dave

On Thu, Oct 30, 2014 at 1:10 PM, Andrea Allan
<aallan at coas.oregonstate.edu> wrote:
> Hello,
>
> I am currently struggling with trying to diagnose small, but very noticeable
> differences between raster images (png workstation) created in NCL 6.1.2 and
> the newest version 6.2.1, using the exact same code and data files in both
> cases.  Large-scale patterns in the data are consistent; however, something
> has changed between the two versions of NCL that make the data shift ever so
> slightly (see attached images).
>
> I've perused all the changes made in the the new version of NCL, and while
> it is hard to pinpoint the problem, could this be related to the change in
> how transparency is handled in raster contouring, or the raster contouring
> method itself?  Searching the ncl-talk archives, I came across this
> statement from another raster image-related problem:
>
> "I think the problem is that the old workstation types do not understand
> transparency in colors."
>
> I have experimented with res at cnMissingValFillColor to no avail.  We have
> also looked at data resolution vs. screen resolution, and while that makes a
> difference within the figure, it does not solve the discrepancy between
> versions.  Any insight regarding this issue is greatly appreciated.
>
> Andrea
>
>
> ~~~
> Andrea M. Allan
> Postdoctoral Research Associate
> College of Earth, Ocean, and Atmospheric Sciences
> Oregon State University
> 112 Burt Hall
> 541-737-3427
> aallan at coas.oregonstate.edu
> ~~~
>
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