GT counts changed after preprocessing

[Yiming-M]

Hi @dylran ,

I think these lines

crowddiff/cc_utils/preprocess_shtech.py

Line 143 in 8167f0b

densities = create_overlapping_crops(density, image_size, 0.5)

crowddiff/cc_utils/preprocess_ucf.py

Line 147 in 8167f0b

densities = create_overlapping_crops(density, image_size, 0.5)

crowddiff/cc_utils/preprocess_jhu.py

Line 296 in 8167f0b

densities = create_overlapping_crops(density, image_size, overlap)

changed the ground-truth count per image, since overlapping crops were used.

To avoid this, maybe we should consider to:

1. Resize each image so that its width and height are multiples of 256;
2. Divide images and density maps into non-overlapping 256x256 patches.

Many thanks,
Yiming