trevor-m / tensorflow-bicubic-downsample

tf.image.resize_images has aliasing when downsampling and does not have gradients for bicubic mode. This implementation fixes those problems.

tensorflow-bicubic-downsample

tf.image.resize_images has aliasing when downsampling and does not define gradients for bicubic mode. This implementation fixes those problems.

Example

These images have been downsampled by a factor of 4 from the original. The results from this code matches the scipy.misc.imresize results exactly.

Method	Result	Comments
Original		This is the original full res image.
tf.images.resize_images		TF's implementation has aliasing
scipy.misc.imresize		Proper bicubic downsampling
This code		Matches scipy exactly

Usage

from bicubic_downsample import build_filter, apply_bicubic_downsample

# First, create the bicubic kernel. This can be reused in multiple downsample operations
k = build_filter(factor=4)

# Downsample x which is a tensor with shape [N, H, W, 3]
y = apply_bicubic_downsample(x, filter=k, factor=4)

# y now contains x downsampled to [N, H/4, W/4, 3]