Image resizing in the discrete cosine transform domain

Image resizing is a task that must often be done when processing digital images. We present a novel approach to resize images by operating entirely in the discrete cosine transform (DCT) domain. We implement the lowpass filter for anti-aliasing or anti-imaging using the convolution-multiplication property of the DCT. We perform the equivalent of pixel-domain downsampling or upsampling by simple manipulation of the DCT coefficients. Our approach can be used as a standalone image resizing tool or it can be integrated into any image compression system based on a block DCT, such as JPEG, to provide an image resizing capability with relatively little additional complexity.