[SOLVED] Automatic crop not working with this

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Guest 2
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[SOLVED] Automatic crop not working with this

Post by Guest 2 »

I have uploaded to https://www5.zippyshare.com/v/Z7LXwrny/file.html a video that gives automatic crop some problems.

Dunno if the black is not really black or what. :lol:
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admin
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Re: Automatic crop not working with this

Post by admin »

It's not really black. And there is a green tinge along the left border, and a red one along the right, that would force you to manually crop even if I revised the threshold for black.
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Re: Automatic crop not working with this

Post by Guest 2 »

admin wrote:
Mon Apr 30, 2018 12:24 pm
It's not really black. And there is a green tinge along the left border, and a red one along the right, that would force you to manually crop even if I revised the threshold for black.
A bad digital conversion indeed.

Very nice eyes you have to see the green and red. I did not notice at first sight.
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Re: Automatic crop not working with this

Post by admin »

My eyes aren't so great. I had changed the threshold for testing and it removed the "black", but it made the tinges jump out at me. Then I zoomed in with my magnifier app. ;)
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Re: Automatic crop not working with this

Post by Guest 2 »

admin wrote:
Mon Apr 30, 2018 6:41 pm
My eyes aren't so great. I had changed the threshold for testing and it removed the "black", but it made the tinges jump out at me. Then I zoomed in with my magnifier app. ;)
Do you plan to release a version with "black threshold"?
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Re: Automatic crop not working with this

Post by admin »

Sure, why not.
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Re: Automatic crop not working with this

Post by Guest »

Wouldn't manually adjusting the black threshold effectively be the same as using the manual adjustment for crop, only with all the trial and error required to get the proper result?
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Re: Automatic crop not working with this

Post by admin »

I suppose the argument would be that you can set a preferred threshold once, set and forget, whereas your approach would have to be done for every video. My choice of threshold was pretty arbitrary and Guest 2's file is not that far off. Another thing I could do is just raise the threshold for non-black. Still thinking about it...
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Re: Automatic crop not working with this

Post by Guest »

I find that if I pick a frame with high contrast the threshold is accurate probably 95% of the time or better
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Re: Automatic crop not working with this

Post by admin »

Raised the non-black threshold to 24 from 16. This solves the issue in a simple way.
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