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Re: [Openexr-devel] OpenEXR Perceptual Image Differencing


From: Ryan Heniser
Subject: Re: [Openexr-devel] OpenEXR Perceptual Image Differencing
Date: Wed, 31 May 2017 10:22:19 +0930

Hi Larry,

Thank you for taking the time to provide such a thorough response. Sorry, you had to repeat yourself. I just found Thiago’s post about this from 2014 (http://lists.openimageio.org/pipermail/oiio-dev-openimageio.org/2014-August/013430.html). Yes, the --diff option with --fail 0.05 and --failpercent 0.1 are working well to address LSB error for my automated tests. For anyone new to oiiotool, --fail and --failpercent must go before —diff.

Thank you,
Ryan


On 31 May 2017, at 5:07 am, Larry Gritz <address@hidden> wrote:

I should add that, while -pdiff seemed like a good idea at the time, I'm not sure it's any better in practice than using regular --diff with wisely chosen epsilons to allow a certain amount of LSB error to not be counted as failure. I do that all the time for testsuite image comparisons, where I expect just a little bit of error against the reference output, for different platforms or different versions of dependent libraries.

Oh my, this is embarrassing. I see now that the oiiotool docs do not even explain how those thresholds can be set. So sorry. The undocumented commands are --fail, --failpercent, --warn, --warnpercent, --hardfail.  It may be undocumented in the oiiotool section of the OIIO docs, but the same commands are explained in the "idiff" section of the docs (they work the same in the two programs). I'll get that oversight fixed.

It's also been suggested that I look into a replacement (or additional) perceptual diff based on CIEDE2000 or DE2000K (google them for details). Seems like a good idea, but I haven't had time to do it. I'd certainly be very supportive if anybody felt like it would be a project they wanted to work on and submit it as a PR.


On May 29, 2017, at 10:16 PM, Ryan Heniser <address@hidden> wrote:

Ugg… Sorry, I overlooked

oiiotool --help
    ...
    --pdiff                  Print report on the perceptual difference of two images


On 30 May 2017, at 2:34 pm, Ryan Heniser <address@hidden> wrote:

Is there a popular or de facto industry standard tool for OpenEXR perceptual image differencing? 

Kind regards,

ryan heniser
senior shading technical director | address@hidden
rising sun pictures | http://www.rsp.com.au
+61 8 8400 6400 

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