2.39: Error opening png file

[Stepa_ua]

I use Win7 x64. After the XnView updating to version 2.39 I have found out that it is impossible to open one of graphic files.

The error of reading is shown only on this file, other png files open without problems.

[XnTriq]

Welcome to the forum, Stepa_ua.

I can confirm that XnView Classic v2.37 and v2.39 as well as MP v0.83 don't like SoftJig.png. I had no problem viewing it with v1.99 though, and TweakPNG gives it a clean bill of health.

Update:

p136095.png

[xnview]

The error is 'IDAT: invalid distance too far back', from Libpng they recommand to use "contrib/tools/pngfix", "pngcrush" to fix such bad file.

[XnTriq]

The error is 'IDAT: invalid distance too far back', from Libpng they recommand to use "contrib/tools/pngfix", "pngcrush" to fix such bad file.

Thanks for the hint!

Code: Select all

pngcrush.exe X:\in\SoftJig.png X:\out\SoftJig.png

  Recompressing IDAT chunks in X:\in\SoftJig.png to X:\out\SoftJig.png
   Total length of data found in critical chunks            =     13573
While converting X:\in\SoftJig.png to X:\out\SoftJig.png:
  pngcrush caught libpng error:
   IDAT: invalid distance too far back

   Critical chunk length, method  12 (ws 15 fm 0 zl 0 zs 0) =        99

Code: Select all

pngcrush.exe -fix X:\in\SoftJig.png X:\out\SoftJig.png

  Recompressing IDAT chunks in X:\in\SoftJig.png to X:\out\SoftJig.png
   Total length of data found in critical chunks            =     13573
   Critical chunk length, method   1 (ws 15 fm 0 zl 4 zs 0) =     17795
   Critical chunk length, method   2 (ws 15 fm 1 zl 4 zs 0) >     17795
   Critical chunk length, method   3 (ws 15 fm 5 zl 4 zs 1) >     17795
   Critical chunk length, method   4 (ws 15 fm 0 zl 9 zs 1) =     13445
   Critical chunk length, method   7 (ws 15 fm 0 zl 9 zs 0) >     13445
   Best pngcrush method        =   4 (ws 15 fm 0 zl 9 zs 1) =     13445
     (0.94% critical chunk reduction)
     (0.94% filesize reduction)

p136130.png

[helmut]

The error is 'IDAT: invalid distance too far back', from Libpng they recommand to use "contrib/tools/pngfix", "pngcrush" to fix such bad file.

Thank you for checking, Pierre. Perhaps XnView can display a more detailed error message which points to the problem.

[Stepa_ua]

Thank you! This file is really easy to fix by using Pngcrush or OptiPNG.