Patent ID: 8463057
Filing Date: 2013-06-11
Classification: H03M,H04N

Abstract:
1. An image encoding apparatus that encodes image data, comprising: an input unit that inputs pixel blocks each constituted by a plurality of pixels, in a preset scanning order, from encoding target image data; an encoder that performs frequency conversion on image data in each pixel block input by the input unit, separates converted coefficients obtained by the frequency conversion into an upper-bit portion that is higher than a bit position specified by a boundary bit position determined based on a predetermined criterion and a lower-bit portion that is lower than or equal to the boundary bit position, and generates encoded data; a deletion unit that deletes a portion equivalent to a set number of bits N, with respect to the lower-bit portion generated from each pixel block in the encoded data generated by the encoder, and when the boundary bit position in a pixel block of interest is n, deletes N bits starting from a least significant bit of the lower-bit portion of the pixel block of interest if N≦n, and deletes bits starting from the least significant bit of the lower-bit portion of the pixel block of interest up to the n bit if N>n; a calculating unit that calculates, for an entire image, distortion that occurs due to encoded data being deleted by the deletion unit; a setting unit that sets an allowable distortion value; and a code stream generating unit that obtains a value at which a number of bits i is maximized at or below the allowable distortion value set by the setting unit, from among evaluation values calculated by the calculating unit, determines the bit number i as the number of bits N to be deleted by the deletion unit, causes the deletion unit to execute deletion, converts encoded data remaining after deletion into a data structure in a preset format, and outputs the resultant data.