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Thread: Id there a PNG Coparison/verification tools

  1. #1
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    IS there a PNG comparison/verification tool

    I want to compare A.png to A.new.png and make sure they both show the exact same pixel info/decodes to the exact same picture. E.G after running a bit but-load of optimization on one of hem.
    Is there a tool for that? preferably more or less automatic for sevarel 100's of png's

  2. #2
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    You can use ffmpeg to convert png to bmp, then use:
    fc.exe /b file_1 file_2
    (File Compare Binary Mode) which is part of Windows to compare the bmp against another bmp.
    Assuming your files are named in a way which makes finding the file to compare against easy then automating this whole process can be done in a batch script across any number of files you have.

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    perhaps this tool could be useful, but is barely tested and could have limitations. it is very simple stuff so it should be much faster than other metrics and use less memory. 0 means decoded raw pixel should be the same. note that it does not care of non-critical chunks such as iCCP, etc.

    Code:
    >timer dssim 1.png 2.png
    0.00000000      2.png
    
    
    Kernel  Time =     0.078 =    1%
    User    Time =     5.959 =   98%
    Process Time =     6.037 =   99%    Virtual  Memory =    249 MB
    Global  Time =     6.040 =  100%    Physical Memory =    251 MB

    Code:
    >timer butteraugli 1.png 2.png
    0.087274
    
    
    Kernel  Time =     4.165 =    4%
    User    Time =    97.157 =   95%
    Process Time =   101.322 =   99%    Virtual  Memory =   1182 MB
    Global  Time =   101.660 =  100%    Physical Memory =    970 MB

    Code:
    >timer pngdiff 1.png 2.png
    0.000031
    
    
    Kernel  Time =     0.000 =    0%
    User    Time =     0.140 =  100%
    Process Time =     0.140 =  100%    Virtual  Memory =     56 MB
    Global  Time =     0.140 =  100%    Physical Memory =     57 MB
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	1.png 
Views:	22 
Size:	755.8 KB 
ID:	7574   Click image for larger version. 

Name:	2.png 
Views:	27 
Size:	755.8 KB 
ID:	7575  
    Attached Files Attached Files

  4. #4
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    Thank you all for the suggestions

    I think BMP has some kind of time stamp in it i believe (by memory i might be wrong) last time idid some BMP comparions identical pictures came out with different hashes.

    The the ddsim sounds really what im looking for.


    thank you all again

  5. #5
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    The pngdiff seems to work really nice. The comparison is not affected by meta tags that would change the visuals of the picture. it semd to compare raw pixel data only which is perfect for my case

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