MIN Pooling

Hi All,

The Min pooling operator can be achieved by applying convolution by -1 , Max pooling and convolution by -1 again.
However, it would be nice to have the MIN pooling operator, so I decided to try to add the MIN operator in the pooling layer but since it did not work for me. I happy to have your help.
I follow this link:
https://github.com/BVLC/caffe/pull/3998/commits/51d38a4b34bddffb00871ac8d8fd3020b7309132
Note that this links referred to files that do not exist in the current version of Caffe I am using, therefore I searched for similar codes in my current Caffe and modified the files, and these are:

```
Link – file name Corresponding file name
```

1 include/caffe/vision_layers.hpp include/caffe/layer/pooling_layer.hpp
include/caffe/util/cudnn.hpp
2 src/caffe/layers/pooling_layer.cpp src/caffe/layers/pooling_layer.cpp
3 src/caffe/layers/pooling_layer.cu src/caffe/layers/pooling_layer.cu
4 src/caffe/proto/caffe.proto src/caffe/proto/caffe.proto

Once I compiled I got few errors and I modified few addition places:
spp_layer.cpp
caffe.pb
layer_factory.cpp

**Then I compiled successfully the entire solution. At run I got this error:

**
I0602 13:47:15.095408 10676 solver.cpp:91] Creating training net from net file: run_siam_train_val_1.prototxt
[libprotobuf ERROR D:\ThirdPartyLibrary\protobuf\src\google\protobuf\text_format.cc:291] Error parsing text-format caffe.NetParameter: 4176:5: Unknown enumeration value of "MIN" for field "pool".
F0602 13:47:15.098409 10676 upgrade_proto.cpp:68] Check failed: ReadProtoFromTextFile(param_file, param) Failed to parse NetParameter file: run_siam_train_val_1.prototxt
**\* Check failure stack trace: ***

The caffe version I use I download on Feb-04_2016.

My modified files are attached:
If someone can help me it would be great.

Thanks
Jhon