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vlfeat / matconvnet

MatConvNet: CNNs for MATLAB
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Input preprocessing with Alexnet #745

Open hojin4671 opened 7 years ago

hojin4671 commented 7 years ago

Hi,

Thank you for providing nice toolbox. Just I have one question. I am using pre-trained alexnet model to know the change according to signal-to-noise ratio. My input image is rescaled to have small range (e.g., 108 to 148), and subtracted by "net.meta.normalization.averageImage". In this case, the accuracy falls down up to almost zero. Visually, the input is well recognized, but CNN cannot.

Why this happened? CNN can not handle this kind of variance? or just problem of Alexnet? Do I have to zscoring? or other normalization methods? Please help me.

lenck commented 7 years ago

Maybe try to change the range just a bit? (e.g. [10 ... 245]) where the network should work fine. To see if the issue is in your code or in the network...