[Mono-bugs] [Bug 571381] New: Incorrect information returns by Bitmap.GetPixel() - only Alpha-channel matches

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http://bugzilla.novell.com/show_bug.cgi?id=571381

http://bugzilla.novell.com/show_bug.cgi?id=571381#c0


           Summary: Incorrect information returns by Bitmap.GetPixel() -
                    only Alpha-channel matches
    Classification: Mono
           Product: Mono: Class Libraries
           Version: 2.4.x
          Platform: x86
        OS/Version: openSUSE 11.2
            Status: NEW
          Severity: Major
          Priority: P5 - None
         Component: Sys.Drawing.
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: vagrod at live.ru
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---
           Blocker: ---


Created an attachment (id=336993)
 --> (http://bugzilla.novell.com/attachment.cgi?id=336993)
Screenshot that shows information abount the first pixel of the same png image
under Windows and Linux

User-Agent:       Opera/9.80 (Windows NT 6.1; U; en) Presto/2.5.18
Version/10.50

I have the same png image under my Windows 7 7600 and Open Suse 11.2 platforms. 
When I call this code from Windows:

bmp = Bitmap.FromFile("filename")
MessageBox.Show(bmp.GetPixel(0,0).ToString)

I see [237, 171, 238, 219]

The same code (with the same image) under Linux is returning: [237, 158, 221,
203] 
Only the alpha channel matches (237 in this case)

This issue presents on Ubuntu 9.10, Mandriva 2010 and openSuse 11.2
I installed mono version 2.6 and found that bug too.

BUT!
The code

Dim bmp As Bitmap = New Bitmap(10, 10)
bmp.SetPixel(0,0,Color.FromARGB(12,34,56,78))
MessageBox.Show(bmp.GetPixel(0,0).ToString)

will return [12, 34, 56, 78] under all systems, so I decided that bug in
System.Drawing.Image.FromFile() function.

Reproducible: Always

Steps to Reproduce:
Run the code 

Dim bmp As Bitmap = Bitmap.FromFile("filename")
MessageBox.Show(bmp.GetPixel(0,0).ToString)

under Windows and Linux with same image and compare results
Actual Results:  
Information about the pixel differs under Windows and Linux

Expected Results:  
Information about the pixel must be same under Windows and Linux

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