[Pnet-developers] [bugs #10445] Exception in PNG Reading loading an image

[Deryk Robosson]

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/**************************************************************************/
[bugs #10445] Latest Modifications:

Changes by: 
                Deryk Robosson <address@hidden>
'Date: 
                Sun 09/26/2004 at 02:53 (GMT)

------------------ Additional Follow-up Comments ----------------------------
I believe this may be related to the Adam7 Interlacing some how.  PNG files 
without, do not appear to have this exception thrown.  However the test image2 
provided in the archive below spits out a 255 value on exception and my test 
image from GIMP a 170 value.  Both of these numbers would be correct to have 
the exception thrown per the PNG specs as there are only 5 filter values, 0-4

File info for the one that is throwing the exception is:
  Image Width: 54 Image Length: 52
  Bitdepth (Bits/Sample): 8
  Channels (Samples/Pixel): 4
  Pixel depth (Pixel Depth): 32
  Colour Type (Photometric Interpretation): RGB with alpha channel
  Image filter: Single row per byte filter
  Interlacing: Adam7 interlacing
  Compression Scheme: Deflate method 8, 32k window
  Resolution: 2834, 2834 (pixels per meter)
  FillOrder: msb-to-lsb
  Byte Order: Network (Big Endian)
  Number of text strings: 1 of 9
    Comment (xTXt deflate compressed):


I was able to duplicate this by creating an image in GIMP and saving with Adam7 
Interlace, file info for that file is:

  Image Width: 256 Image Length: 256
  Bitdepth (Bits/Sample): 8
  Channels (Samples/Pixel): 3
  Pixel depth (Pixel Depth): 24
  Colour Type (Photometric Interpretation): RGB
  Image filter: Single row per byte filter
  Interlacing: Adam7 interlacing
  Compression Scheme: Deflate method 8, 32k window
  Resolution: 2834, 2834 (pixels per meter)
  FillOrder: msb-to-lsb
  Byte Order: Network (Big Endian)
  Number of text strings: 0 of 0






/**************************************************************************/
[bugs #10445] Full Item Snapshot:

URL: <http://savannah.gnu.org/bugs/?func=detailitem&item_id=10445>
Project: DotGNU Portable.NET
Submitted by: Heiko Weiss
On: Mon 09/20/2004 at 09:11

Category:  None
Severity:  5 - Average
Item Group:  None
Resolution:  None
Privacy:  Public
Assigned to:  None
Status:  Open


Summary:  Exception in PNG Reading loading an image

Original Submission:  In some cases the png reader throws an exception 
System.FormatException: invalid filter type byte f
or scanline 0: 255
while loading an image.

Example with images atached.
Image1.png works well. Image2.png throws the exception.

Follow-up Comments
------------------


-------------------------------------------------------
Date: Sun 09/26/2004 at 02:53       By: Deryk Robosson <drobosson>
I believe this may be related to the Adam7 Interlacing some how.  PNG files 
without, do not appear to have this exception thrown.  However the test image2 
provided in the archive below spits out a 255 value on exception and my test 
image from GIMP a 170 value.  Both of these numbers would be correct to have 
the exception thrown per the PNG specs as there are only 5 filter values, 0-4

File info for the one that is throwing the exception is:
  Image Width: 54 Image Length: 52
  Bitdepth (Bits/Sample): 8
  Channels (Samples/Pixel): 4
  Pixel depth (Pixel Depth): 32
  Colour Type (Photometric Interpretation): RGB with alpha channel
  Image filter: Single row per byte filter
  Interlacing: Adam7 interlacing
  Compression Scheme: Deflate method 8, 32k window
  Resolution: 2834, 2834 (pixels per meter)
  FillOrder: msb-to-lsb
  Byte Order: Network (Big Endian)
  Number of text strings: 1 of 9
    Comment (xTXt deflate compressed):


I was able to duplicate this by creating an image in GIMP and saving with Adam7 
Interlace, file info for that file is:

  Image Width: 256 Image Length: 256
  Bitdepth (Bits/Sample): 8
  Channels (Samples/Pixel): 3
  Pixel depth (Pixel Depth): 24
  Colour Type (Photometric Interpretation): RGB
  Image filter: Single row per byte filter
  Interlacing: Adam7 interlacing
  Compression Scheme: Deflate method 8, 32k window
  Resolution: 2834, 2834 (pixels per meter)
  FillOrder: msb-to-lsb
  Byte Order: Network (Big Endian)
  Number of text strings: 0 of 0






File Attachments
-------------------

-------------------------------------------------------
Date: Mon 09/20/2004 at 09:11  Name: TestPNG.zip  Size: 10.37KB   By: brubbel
Sample which throws the exception.
http://savannah.gnu.org/bugs/download.php?item_id=10445&amp;item_file_id=1686






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