Efficient image down-conversion for mixed field/frame-mode macroblocks

An efficient image resizing algorithm in the compressed domain with mixed field/frame-mode macroblocks is proposed. A 16×16 field/frame-mode macroblock is converted into an 8×8 reduced block in the discrete cosine transform (DCT) domain using a modified inverse DCT (IDGT) kernel which performs stronger lowpass filtering than the simple truncation in the DCT domain. Experimental results show that the proposed algorithm provides the resized image quality similar to an existing method with significantly lower computational complexity.