Image resampling

Image resampling evaluates image data on a new sampling grid, often while resizing, rotating or rectifying an image. An output pixel is mapped to a source location, which may lie between stored source pixels. An interpolation rule estimates its value; a boundary rule handles locations outside the recorded image.^[ref]

For example, bilinear interpolation at the center of four source samples with values $0,0,0,100$ gives their equally weighted mean, 25. Nearest-neighbor interpolation instead selects one sample and retains its value. These methods trade smoothness against preservation of discrete labels. Reducing image size also changes the sampling rate: a low-pass filter before subsampling can suppress aliasing, whereas interpolation alone cannot guarantee its removal. Stereo rectification uses image resampling to construct aligned virtual views without physically moving either camera.