Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
c:\>set MAGICK_TMPDIR=C:/WINDOWS/TEMP
c:\>convert -version
Version: ImageMagick 6.9.1-10 Q16 x86 2015-07-25 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC HDRI Modules OpenMP
Delegates (built-in): bzlib cairo freetype jng jp2 jpeg lcms lqr openexr pangocairo png ps rsvg tiff webp xml zlib
c:\>convert rose: PNG:- | identify -quiet -
-=>C:/WINDOWS/TEMP/magick-7368uBkzxXLBcBZC PNG 70x46 70x46+0+0 8-bit sRGB 6.97KB 0.000u 0:00.002
c:\>convert rose: PNG8:- | identify -quiet -
-=>C:/WINDOWS/TEMP/magick-1560lOhfVRfBpUOF PNG 70x46 70x46+0+0 8-bit sRGB 113c 2.17KB 0.000u 0:00.003
c:\>convert rose: PNG24:- | identify -quiet -
-=>C:/WINDOWS/TEMP/magick-7312cg0RIMk4ko-c PNG 70x46 70x46+0+0 8-bit sRGB 6.97KB 0.000u 0:00.001
c:\>convert rose: PNG32:- | identify -quiet -
-=>C:/WINDOWS/TEMP/magick-81287gdAE8f9mxlN PNG 70x46 70x46+0+0 8-bit sRGB 7.96KB 0.000u 0:00.002
c:\>convert rose: PNG48:- | identify -quiet -
convert.exe: unable to open image `PNG48:-': Permission denied @ error/blob.c/OpenBlob/2695.
identify.exe: no decode delegate for this image format `' @ error/constitute.c/ReadImage/501.
c:\>convert rose: PNG64:- | identify -quiet -
convert.exe: unable to open image `PNG64:-': Permission denied @ error/blob.c/OpenBlob/2695.
identify.exe: no decode delegate for this image format `' @ error/constitute.c/ReadImage/501.
c:\>convert rose: PNG00:- | identify -quiet -
convert.exe: unable to open image `PNG00:-': Permission denied @ error/blob.c/OpenBlob/2695.
identify.exe: no decode delegate for this image format `' @ error/constitute.c/ReadImage/501.
I instaled ImageMagick to D:\Program Files\ImageMagick-6.9.1-Q16-HDRI from binary release file ImageMagick-6.9.1-10-Q16-HDRI-x86-dll.exe, and if I invoked the same command from D:\, one error from convert disappears, but still no output to STDOUT.
6.9.1-9 and 6.9.10 work for me. Note that the PNG00, PNG48, and PNG64 subformats were added at version 6.8.2-0, so I'd expect to see what you saw if running a version older than that.
Maybe there's something going on behind the scenes that causes "convert -version" to report the current version but the PNG decoder is coming from an older version. That is to say, you're picking up the current version.h but an older executable.
convert -list format | grep PNG
identify -list format | grep PNG
say? Are PNG00, PNG48, and PNG64 among the listed formats for both commands? I suppose they are, because you said that PNG48 worked for you when directing the output to a file.
This is not a Windows only bug but a 'Modules' only bug. Your Cygwin 6.9.1-3 version is statically linked instead of compiled with 'Modules' enabled. I will commit a fix for this tomorrow and this will work properly in the next version of ImageMagick (6.9.2-0)
convert -list format | grep PNG
identify -list format | grep PNG
say? Are PNG00, PNG48, and PNG64 among the listed formats for both commands? I suppose they are, because you said that PNG48 worked for you when directing the output to a file.