Apparatus for encoding and decoding image and method thereof

摘要

An image encoding and/or decoding apparatus and method are provided. The image encoding apparatus includes: a transform unit removing spatial redundancy by transforming an original image being input; an allowable noise obtaining unit obtaining an allowable noise from the original image; a quantization parameter determination unit determining a quantization parameter by using the allowable noise; a quantization unit generating a quantized coefficient, by quantizing a transform coefficient provided from the transform unit by using the quantization parameter; and an entropy encoding unit entropy encoding the quantized coefficient to remove statistical redundancy.

主权项

1. An image encoding apparatus, comprising:
a computer, comprising: a transform unit to remove spatial redundancy by transforming an original image; an allowable noise obtaining unit to obtain an allowable noise, defined as an error image which does not raise subjective loss between the original image and a color quantized image of the original image, by using a result of color quantization of the original image in units of frames or in units of predetermined blocks; a quantization parameter determination unit to determine a quantization parameter by using the allowable noise; a quantization unit to generate a quantized coefficient, by quantizing a transform coefficient provided from the transform unit by using the quantization parameter; a scanning order determination unit to determine a scanning order with respect to quality layers determined using the allowable noise, wherein each of the quality layers comprises bit planes determined by using the allowable noise and the scanning order is from an upper quality layer towards a lower quality layer; and an entropy encoding unit to entropy encode the quantized coefficient in the scanning order with respect to the quality layers to remove statistical redundancy, wherein the quantization parameter determination unit determines the quantization parameter of each of coding blocks by gradually increasing the quantization parameter from a smaller value to a bigger value with a predetermined variation step so that a quantization noise generated as a result of quantization with respect to each of the coding blocks can be equal to or less than the allowable noise, and wherein the scanning order determination unit determines the allowable noise based on a color number and each of the quality layers is determined by using a subsequent allowable noise obtained by a subsequent color number that is less than the color number used to determine the allowable noise.