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Relax limit checks on gamma values.

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As suggested in the comments gamma values outside the range currently permitted
by png_set_alpha_mode are useful for HDR data encoding.  These values are
already permitted by png_set_gamma so it is reasonable caution to extend the
png_set_alpha_mode range as HDR imaging systems are starting to emerge.

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler 2016-01-29 18:09:49 -08:00
parent 2d3bd021d0
commit f1eafe8b01
1 changed files with 5 additions and 2 deletions
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pngrtran.c
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@ -289,9 +289,12 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
* is expected to be 1 or greater, but this range test allows for some * is expected to be 1 or greater, but this range test allows for some
* viewing correction values. The intent is to weed out users of this API * viewing correction values. The intent is to weed out users of this API
* who use the inverse of the gamma value accidentally! Since some of these * who use the inverse of the gamma value accidentally! Since some of these
* values are reasonable this may have to be changed. * values are reasonable this may have to be changed:
*
* 1.6.x: changed from 0.07..3 to 0.01..100 (to accomodate the optimal 16-bit
* gamma of 36, and its reciprocal.)
*/ */
if (output_gamma < 70000 || output_gamma > 300000) if (output_gamma < 1000 || output_gamma > 10000000)
png_error(png_ptr, "output gamma out of expected range"); png_error(png_ptr, "output gamma out of expected range");
/* The default file gamma is the inverse of the output gamma; the output /* The default file gamma is the inverse of the output gamma; the output