Digital image coding/decoding apparatus and method for evaluating the quality of images transmitted using watermarking

摘要

Digital image coding/decoding apparatus using watermarking, and methods thereof are provided. The digital image coding apparatus includes a first discrete wavelet transform portion for receiving a host image to be transmitted and performing discrete wavelet transform thereon, thereby outputting M×M discrete wavelet coefficients where M is a predetermined positive integer, an original signature image storage portion for storing an image suitable to an analysis of variance (ANOVA) technique as an original signature image, a second discrete wavelet transform portion for receiving the original signature image and performing discrete wavelet transform thereon to obtain N×N wavelet coefficients, N being another predetermined integer smaller than M, and a coefficient replacement/combination portion for replacing and combining N×N location data with N×N wavelet coefficients selected among M×M wavelet coefficients in accordance with a predetermined rule to then output the N×N location data and replaced M×M wavelet coefficients. A small amount of the image samples are transmitted in confidence as a signature image using watermarking, without affecting the original images. Then, during decoding, an ANOVA technique is applied to the restored signature image and the original signature image, thereby accurately predicting the quality of the host image.