[QUESTION] image augmentor -- crop range of image -- seems different from openpose

[gjbang]

Hi, I'm sorry to disturb you. I have a small question about data augmentation.

Towards def apply_image(self, meta) of class CropTransform(Transform) in dataset/augmentors.py, when coordinate of left_up point is negative, it seems that area of original image smaller than 368 * 368 is returned.

For example, suppose that the coordinates of left_up point is (-10,-20), so the valid
area of original image will be [0:348, 0:358] according the code, and this area will be given the cropped image, while the rest array value of cropped image will be padded by border_value(128).

But when I read the source code for data transform of openpose-caffe_train in ./src/caffe/cpm_data_transformer.cpp, I find its crop area will be just 368*368 pixels from original image, and not be padded by some value.

Specific code is in function：template<typename Dtype> void CPMDataTransformer<Dtype>::Transform(const Datum& datum, Dtype* transformed_data) located at line 248.

So could you please tell me whether crop strategy in your code is designed for some special target? Besides, does image padded by border_value helps improve the accuracy?

Thank you very much!