Abstract: In image compression utilizing wavelet conversion for dividing an image of one screen into subbands through multiple steps, subband data of a higher frequency is predicted from subband data of a lower frequency, subtraction is carried out between data obtained by the prediction and an actual higher-frequency subband coefficient at the same position as that for the predicted data to provide a difference, and only the difference is coded. By coding only the difference in this manner, a high compression ratio can be realized.

Abstract: A character reading apparatus including a scanning unit manually moved along a line of characters for periodically and optically scanning the character and producing character pattern data concerning the scanned character, a memory accommodating conditional data prescribing effective character patterns and a pattern identification unit for executing identification process for a character pattern obtained from the scanning unit when the character pattern is determined to be effective, is disclosed. The character reading apparatus further includes an optimum character detection circuit, which compares the widths of character patterns represented by effective character pattern data to detect a character pattern having the greatest width and causes identification process to be executed for the character pattern data having the largest width.