[gdal-dev] Troubleshooting palette management. Potential bug in palette for overviews?

[Daniele Romagnoli]

JAI-ImageIO TIFFDecompressor does the same (Line 0888):
https://java.net/projects/jai-imageio-core/sources/svn/content/trunk/src/share/classes/com/sun/media/imageio/plugins/tiff/TIFFDecompressor.java?rev=254

(also putting an imageio-ext link for quicker reference)
https://github.com/geosolutions-it/imageio-ext/blob/master/plugin/tiff/src/main/java/it/geosolutions/imageio/plugins/tiff/TIFFDecompressor.java#L900

Note the:
redLut[i] = (byte)((colorMap[i]*255)/65535);
which results into using a 257 scale factor.

Cheers,
Daniele


On Fri, Nov 25, 2016 at 11:27 AM, Ari Jolma <ari.jolma at gmail.com> wrote:

> 24.11.2016, 18:01, Even Rouault kirjoitti:
>
>
>
> Could be worth fixing that if that cause issues (apparently in your use
> case at least), but I'd be interested by information of what is the
> standard/recommanded/best-practice-in-the-industry/etc... formulas to use
> for the mapping between the [0,255] and [0,65535] ranges.
>
>
> At least in the GTK circles it seems to be a standard practice to use the
> 257 as the scaling factor. See for example
>
> http://gtk2-perl.sourceforge.net/doc/pod/Gtk2/Gdk/Color.html
>
> Ari
>
>
>
>
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