Patent ID: 6584232
Filing Date: 2003-06-24
Classification: H04N

Abstract:
An image encoding apparatus for encoding an object image to generate an encoded image which has an encode amount no larger than a target encode amount, the image encoding apparatus comprising:a relationship storage unit operable to store in advance a first relationship and a second relationship, the first relationship showing a correspondence between a predetermined number of quantization widths and the same number of first encode amounts that are obtained by encoding, for each of the predetermined number of quantization widths, a sample image having a small encode amount, and the second relationship showing a correspondence between the predetermined number of quantization widths and the same number of second encode amounts that are obtained by encoding, for each of the predetermined number of quantization widths, a sample image having a large encode amount; a quantization width determining unit operable to (a) refer to the first relationship in the relationship storage unit to obtain a first quantization width which corresponds to a first encode amount that is closest to the target encode amount, (b) refer to the second relationship in the relationship storage unit to obtain a second quantization width which corresponds to a second encode amount that is closest to the obtained target encode amount, (c) calculate a first predicted encode amount and a second predicted encode amount for the object image using the obtained first and second quantization widths, respectively, (d) predict a third relationship that shows a correspondence between quantization widths and encode amounts, has an increasing/decreasing tendency similar to increasing/decreasing tendencies of the first and second relationships, and includes (i) a correspondence between the first quantization width and the first predicted encode amount and (ii) a correspondence between the second quantization width and the second predicted encode amount, and (e) determine an optimum quantization width that is between the first quantization width and the second quantization width, satisfies the third relationship, and has an encode amount that is approximately the same as the target encode amount; and an encoding unit operable to encode the object image using the optimum quantization width.