Add rounding error (I think)

edited November 2014 in Express Support

Hi All,

Congratulatins n getting HF3 out, looking good!

I was trying compositing with OpenEXR to see how that went and I think I've picked up a math bug (or I'm being stupid I've been working with Nodes for ages instead of layers :-) ) but I think I have this set up correct.

In the attached example I've included just one colour images to try and keep it clear.

If you add two layers together both with the same example AddInput0001.exr file which just contains RGB 0.2, 1, 1 then the result should be RGB 0.4, 1, 1 which I've included for referance that I created in Blender to double check my sanity (AddResult0001.exr)

If you look at the example file I linked assuming I have it set up correctly :-) I get a result of RGB 0.93,1,1  when I do the same operation with layers in Hitfilm I noticed this as I wondered why some of my tests were blowing out.

If you look at that as HSV interestingly the correct output should be H 0.5, S 0.33, V 1.0 where from Hitfilm I get H 0.5, S0.031, V1.0 so it looks like it might just be a decimal point out in the code somewhere.

I had a quick look at the rest of the blend modes and they appeard to work as expected but I didn't look in detail

Hopefuly I haven't just set this up worng in Hitfilm!!

https://www.dropbox.com/s/539wg5883j49qki/add-error.zip?dl=0

Comments

  • I'll point the dev team at this first thing tomorrow. :)

  • edited February 2015

    Hiya, just checked with the lastest build posted and I think this is still broken for add with exr files, could someone see if they can reproduce in case it's something weird on my system or I've done something stupid, example file in the first post.  I was going to do a tutorial on a workflow to get muiti later exr files split out and into hitfilm for compositing but I can't if I can't actualy do to compositonce they are in :-)  It looks like HF could be really good in this space if we can get this solved. 

    Mark

  • Hi All,

    Just tested in release 3 and this is still broken I think, suspect not many playing with open exr just yet so not high priority but it would be really nice if it could be fixed or if someone can tell me I've done the test wrong either fine :) need to use add for the composite stuff and noise reduction I wanted to do.  

    In better news, LUT plug in for vegas, that should go down well!! just tested it in vegas I can now export custom lut's from filmconvert pro and import them with that works as expected happy days!  You should post that on the vegas forums I'm pretty sure there is not one at all for vegas and folks have been asking for a while on and off.

  • AdyAdy Staff
    edited April 2015

    Hi,

    Sorry for the delayed response.

    The data is stored in the OpenEXR format using the linear color space and is converted to sRGB to be used in HitFilm. This conversion is what causes the difference in values. To enable the values to be combined in the way the you describe would require that HitFilm support color profiles, which at the moment in time it does not.

    Ady

  •  Thanks Ady, that makes sense, that's a shame would have been handy to have that as a workflow in and out as open exr, never mind!

    thanks for getting back to me.

  • AdyAdy Staff

    mark_e - No Problem, sorry it wasn't the answer you wanted.

    All the best for your future projects!

    Thanks,
    Ady

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