Rosetta Code

Talk:Percentage difference between images

Revision as of 05:16, 23 June 2011 by Sonia (talk | contribs) (→‎Disagreement research project: it's all how you look at it)

examples

Please provide sample inputs and outputs. --DanBron 23:34, 13 November 2008 (UTC)

Any image can be used, open it in Gimp and save it with 2 different jpeg compression ratio.
Then you have img1.jpg and img2.jpg, so call this script this way (followed by its output):
./script.ml img1.jpg img2.jpg
diff: 0.004283 percent
Blue Prawn 00:01, 14 November 2008 (UTC)
Some of us don't have Gimp. Having images would also make the article/task more aesthetically appealing.
--DanBron 15:04, 14 November 2008 (UTC)
OK, I do understand. Just give me the permition to upload images. As long as I have understood one need to have the bureaucrate statut. Are you able to give me this statut? If not, who have I to ask to get it?
Blue Prawn 08:13, 15 November 2008 (UTC)
I have pictures on my computer at 100 and 50 but file upload is broken at the moment. I will add links to the task when I get them uploaded. --Mwn3d 03:07, 16 November 2008 (UTC)
Could someone run their program with the test images and put the expected results in the task description? --Mwn3d 19:49, 4 December 2008 (UTC)
There you go. Drea 20:19, 4 December 2008 (UTC)

Disagreement research project

The different examples produce slightly different results. It would be good to collect what the different results are (taking into account different precisions in output) and what kind of arithmetic each such example uses, and figure out whether particular examples are actually wrong.

The arithmetic properties I can think of are:

  • integer or floating-point color components
  • integer or floating-point sum
  • when division by image size is done
  • when division by maximum color component value (if not 1.0, e.g. 255) is done

--Kevin Reid 20:03, 29 July 2009 (UTC)

Some of the larger differences likely come from the jpeg decoding. I got 1.78 at first (using djpeg.) I tried the -fast option and it went to 1.84. Switching to convert dropped the answer to the 1.62 range most people were getting. —Sonia 05:16, 23 June 2011 (UTC)

Python Image Library?

Where is the Image library from? --Paddy3118 12:56, 31 December 2009 (UTC)

Here, I think. PIL has a module named Image, at any rate. —Underscore (Talk) 15:08, 31 December 2009 (UTC)
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