============ pngtest pngtest.png ==============

============ pngvalid-simple.sh ==============
PASS: pngvalid --standard (floating point arithmetic)
PASS: pngvalid --standard --progressive-read (floating point arithmetic)
PASS: pngvalid --standard --interlace (floating point arithmetic)
PASS: pngvalid --standard --progressive-read --interlace (floating point arithmetic)
PASS: pngvalid --size (floating point arithmetic)
PASS: pngvalid --size --progressive-read (floating point arithmetic)
pngvalid: pngvalid: transform: +rgb_to_gray(R(0.7978,0.2881,0.0000),G(0.1352,0.7118,0.0000),B(0.0313,0.0001,0.8251))^0.62500[overridden]: caught signal: illegal instruction
pngvalid: 1 errors, 0 warnings
FAIL: pngvalid --transform (floating point arithmetic)

============ pngvalid-full.sh ==============
PASS: pngvalid --gamma-threshold (floating point arithmetic)
Gamma correction error summary

The printed value is the maximum error in the pixel values
calculated by the libpng gamma correction code.  The error
is calculated as the difference between the output pixel
value (always an integer) and the ideal value from the
libpng specification (typically not an integer).

Expect this value to be less than .5 for 8 bit formats,
less than 1 for formats with fewer than 8 bits and a small
number (typically less than 5) for the 16 bit formats.
For performance reasons the value for 16 bit formats
increases when the image file includes an sBIT chunk.

Basic gamma correction:
  8 bit gray:  0.49933
  8 bit color: 0.49933
  indexed:     0.00000
 16 bit gray:  0.74080
 16 bit color: 0.74080
PASS: pngvalid --gamma-transform (floating point arithmetic)

Gamma correction with sBIT:
 16 bit gray:  0.74058
 16 bit color: 0.74058
PASS: pngvalid --gamma-sbit (floating point arithmetic)

Gamma correction with 16 to 8 bit reduction:
 16 bit gray:  1.97052
 16 bit color: 1.97052
PASS: pngvalid --gamma-16-to-8 (floating point arithmetic)

Gamma correction with background:
  8 bit gray:  13.81700
  8 bit color: 19.16293
 16 bit gray:  1.54228
 16 bit color: 57.89386
PASS: pngvalid --gamma-background (floating point arithmetic)

Gamma correction with alpha mode:
  8 bit gray:  17.48251
  8 bit color: 17.48251
 16 bit gray:  309.24044
 16 bit color: 310.97330
PASS: pngvalid --gamma-alpha-mode (floating point arithmetic)
Gamma correction error summary

The printed value is the maximum error in the pixel values
calculated by the libpng gamma correction code.  The error
is calculated as the difference between the output pixel
value (always an integer) and the ideal value from the
libpng specification (typically not an integer).

Expect this value to be less than .5 for 8 bit formats,
less than 1 for formats with fewer than 8 bits and a small
number (typically less than 5) for the 16 bit formats.
For performance reasons the value for 16 bit formats
increases when the image file includes an sBIT chunk.

Basic gamma correction:
  8 bit gray:  128.32752
  8 bit color: 128.32752
  indexed:     128.32752
 16 bit gray:  0.74080
 16 bit color: 0.74080
PASS: pngvalid --gamma-transform --expand16 (floating point arithmetic)

Gamma correction with background:
  8 bit gray:  3204.23995
  8 bit color: 4952.57352
 16 bit gray:  1.29983
 16 bit color: 93.83902
PASS: pngvalid --gamma-background --expand16 (floating point arithmetic)

Gamma correction with alpha mode:
  8 bit gray:  4493.00481
  8 bit color: 4493.00481
 16 bit gray:  309.24044
 16 bit color: 310.97330
PASS: pngvalid --gamma-alpha-mode --expand16 (floating point arithmetic)