Patent ID: 7664334

Claim:
An image encoder comprising: an analyzer which analyzes image data including at least one character area and at least one picture area, and classifies a plurality of unit areas into a character attribute indicating that the image data is in the character area or a picture attribute indicating that the image data is in the picture area; a scalar quantization section which performs scalar quantization for image data of each of the plurality of unit areas using a corresponding one of two quantization coefficients, in accordance with whether said analyzer classifies the image data into the character attribute or the picture attribute; an encoder which encodes the image data of each of the plurality of unit areas which is quantized by said scalar quantization section using a corresponding one of two progressive techniques, in accordance with whether said analyzer classifies the image data into the character attribute or the picture attribute; a post quantization section which performs post quantization for the image data of each of the plurality of unit areas which is encoded by said encoder using a corresponding one of two quantization parameters, in accordance with whether said analyzer classifies the image data into the character attribute or the picture attribute; and a storage section which stores the image data of each of the plurality of unit areas which is post quantized by said post quantization section.