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SSIM and MS-SSIM sometimes generate negative values. #36

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li-zhi opened this issue Oct 14, 2016 · 2 comments
Closed

SSIM and MS-SSIM sometimes generate negative values. #36

li-zhi opened this issue Oct 14, 2016 · 2 comments

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@li-zhi
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li-zhi commented Oct 14, 2016

zli@zhi-ubuntu14-vm:~/Projects/stash/MCE/transcoder/vmaf_oss/vmaf/feature$ ./ssim yuv420p /home/zli/Desktop/debug_ssim/AttackOnTitan_1026_2.yuv /home/zli/Desktop/debug_ssim/AttackOnTitan_5v_1026_2.yuv 1920 1080
ssim: 0 -0.016983
ssim_l: 0 -0.046559
ssim_c: 0 0.665225
ssim_s: 0 0.508533
ssim: 1 -0.018055
ssim_l: 1 -0.046968
ssim_c: 1 0.664024
ssim_s: 1 0.508169
@yuhjay
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yuhjay commented Oct 14, 2016

I think this is related to the c1 and c2 constants in the model. they are created to avoid divided by zero. However, these values only happens to corner case. (very special videos created by purpose). I am not sure why animation cause such problem.

@li-zhi
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li-zhi commented Oct 14, 2016

@yuhjay We've found the root cause and is working on a solution.

li-zhi added a commit that referenced this issue Oct 14, 2016
@li-zhi
Bugfix/#36 ssim msssim negative values (#37)
0a79741 
* Reverse OPT_RANGE_PIXEL_OFFSET back to 0.

* Fix offset for SSIM and MS-SSIM; fix test cases.

* Increment SSIM and MS-SSIM feature extractor version number.

* Update VERSION and CHANGELOG.
@li-zhi li-zhi closed this as completed Oct 17, 2016
nilfm pushed a commit that referenced this issue Dec 8, 2022
Pull request #36: Add more options for vif_kernelscale in float_vif.
36731bf 
Merge in MCE/vmaf-private-lts from feature/add-more-kernelscale-options-for-float-vif-christosb to master

* commit 'd3d56e2c6f45ff2851e4ca238d86ea9fafbce13e':
  Add more options for vif_kernelscale in float_vif.
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@yuhjay @li-zhi