DCT Coefficient Prediction for JPEG Image Coding

The JPEG baseline algorithm follows a block-based coding approach and therefore, it does not explore source redundancy at the sub-block level. This note explores correlation between adjacent rows (or columns) at the block boundaries for predicting DCT coefficients of the first row/column of DCT blocks. Experimental results show that our prediction method reduces the average JPEG DC residual by about 75% for images compressed at the default quality level. The same for AC01/10 coefficients is about 30%. It reduces the final code bits by about 4.55% of the total image code for grey images. Our method can be implemented as a part of the JPEG codec without requiring any changes to its control structure or to its code stream syntax.