Resize backends

Added Pillow backend for resize. Now you can Pillow, OpenCV, pyvips

To pick resize backend:

Pillow

pip install pillow

export ALBUMENTATIONS_RESIZE=pillow

Pyvips

pip install pvips

export ALBUMENTATIONS_RESIZE=pyvips

OpenCV (default)

export ALBUMENTATIONS_RESIZE=opencv

Different resize backend is used in:

• Resize
• RandomScale
• LongestMaxSize
• SmallestMaxSize
• RandomSizedCrop
• RandomResizedCrop
• Downscale

Map resolution range

In a set of transforms we generate pixel map between original and resulting pixels which could be slow. Parameter map_resolution_range allows to generate a smaller size map and upscale after that. Such trick makes transform faster but sightly less accurate.

Affects transforms:

• ElasticTransform
• GridDistortion
• OpticalDistortion
• ThinPlateSpline