1. A method of estimating a quantization table for a compressed image block, the method comprising: performing a first quantization using a table dictionary that includes a number of candidate quantization tables for the compressed image block; performing edge-related filtering on the compressed image block and performing a second quantization using the table dictionary for the filtered compressed image block; and estimating a quantization table for the compressed image block based on energy costs of the first-quantized image block and the second-quantized image block.