Results 1 to 5 of 5

Thread: Id there a PNG Coparison/verification tools

  1. #1
    Member
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    926
    Thanks
    58
    Thanked 116 Times in 93 Posts

    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
    Member
    Join Date
    Feb 2015
    Location
    United Kingdom
    Posts
    176
    Thanks
    29
    Thanked 74 Times in 44 Posts
    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.

  3. #3
    Member
    Join Date
    Apr 2013
    Location
    France
    Posts
    61
    Thanks
    9
    Thanked 20 Times in 17 Posts
    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 pixel should be the same. note that it does not care of non-critical chunks such as iCCP, etc.
    edit: updated tool
    Attached Files Attached Files
    Last edited by cssignet; 9th October 2020 at 14:11.

  4. #4
    Member
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    926
    Thanks
    58
    Thanked 116 Times in 93 Posts
    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
    Member
    Join Date
    Sep 2007
    Location
    Denmark
    Posts
    926
    Thanks
    58
    Thanked 116 Times in 93 Posts
    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

Similar Threads

  1. Replies: 2
    Last Post: 23rd February 2013, 06:01
  2. Comparison of lossless PNG compression tools
    By Surfer in forum Data Compression
    Replies: 54
    Last Post: 19th September 2011, 22:58
  3. Interesting tools
    By lunaris in forum Data Compression
    Replies: 2
    Last Post: 25th August 2009, 23:50

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •