Crop Layer and Scale Layer Error

[Ark]

Hello,

I am training on FCN using caffe-master branch.

1. I am trying to figure out the behaviour of crop layer. I am using the crop function provided by caffe. But I don't understand how it works.
In the deconvolution layer, if I keep filter_size = 2xstride, sometimes it works, sometimes it throws the error that offset is a fraction. Then I have to keep filter_size = 2xStride - 1

Can anyone explain the logic behind it or how to adjust the filter_size?

2. When I give an offset to a crop layer in FCN, is it always fixed for any input image size (which means it is not a center-cropping)?

Best Regards,
ARK

[Evan Shelhamer]

if I keep filter_size = 2xstride

, sometimes it works, sometimes it throws the error that offset is a fraction. 

​[...]​

Can anyone explain the logic behind it or how to adjust the filter_size?

​There are a few subtleties to the coordinate mapping of layers. There can be an off-by-one issue with even and odd filters that you've encountered here. I'm not sure there's a substitute for working through the details of the coordinate mapping part of net specification in order to understand this.​

2. When I give an offset to a crop layer in FCN, is it always fixed for any input image size (which means it is not a center-cropping)?

​The crop offset is a fixed function of the architecture and does not vary with input size. It is the offset that aligns the input with the output.​

 

Evan Shelhamer

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