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I'd like to compute FeatureDistance between two images with a NetGraph:

rs = NetModel["ResNet-152 Trained on ImageNet Competition Data"];
fe = NetTake[rs, {1, -3}]

Ok, so this works:

FeatureNearest[imgs -> {"Index", "Distance"}, FeatureExtractor -> fe]

But then why doesn't this:

FeatureDistance[img1, img2, fe]

enter image description here

Is there a way to turn a NetGraph[] into a valid FeatureExtractorFunction[]?

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  • $\begingroup$ Sorry why use Features stuff ? you are just computing Norm@Differences@fe@{img1,img2 } $\endgroup$ – Fortsaint Nov 18 '18 at 15:27
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Yes, there is a way.

net = NetChain[
   {ConvolutionLayer[32, {3, 3}], AggregationLayer[Mean]},
   "Input" -> NetEncoder[{"Image", {64, 64}, ColorSpace -> "RGB"}]
   ] // NetInitialize

enter image description here

imgs = Table[RandomImage[1, {64, 64}, ColorSpace -> "RGB"], {20}];

fe = FeatureExtraction[imgs, net]

enter image description here

FeatureDistance[imgs[[1]], imgs[[2]], fe]

0.0268319

| improve this answer | |
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  • $\begingroup$ Ok great. However there's something weird going on in FeatureDistance: fe = FeatureExtraction[imgs, NetTake[rs, {1, -3}]] FeatureDistance[ExampleData[{"TestImage", "Lena"}], ExampleData[{"TestImage", "Sailboat"}], fe] the distances are only 0 or 1... unless I set DistanceFunction -> CosineDistance. Do you know what FeatureDistance does by default? $\endgroup$ – user5601 Mar 19 '18 at 13:57
  • $\begingroup$ @user5601 EuclideanDistance. i.stack.imgur.com/ky1wD.png $\endgroup$ – Alexey Golyshev Mar 20 '18 at 8:02

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