= 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.<Geometric Image Transformations in the OpenCV documentation>[Detailed Description, inverse mapping, interpolation and extrapolation]{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>.
Back to article page
