Patent ID: 7702165
Filing Date: 2010-04-20
Classification: H04N

Abstract:
1. An image coding device comprising: an image splitting circuit configured to split an image into a plurality of block images each having plural pixels; a Discrete Cosine Transform (DCT) circuit to configured to perform a DCT processing on the block image to calculate DCT coefficients from the block image; a quantizing circuit configured to quantize the calculated DCT coefficients with respective quantization step sizes specified; a distortion determining circuit configured to determine whether the block image is in a flat state or non-flat state depending on the calculated DCT coefficients from the block image; and a step size determination circuit to configured to specify as quantization step sizes for first DCT coefficients which are DCT coefficients equivalent to one-dimensional DCT coefficient out of the calculated DCT coefficients, adjusting step sizes equal to or smaller than values of the first DCT coefficients for the quantizing circuit, and specifying standard step sizes given beforehand as quantization step sizes for second DCT coefficients other than the first DCT coefficients out of the calculated DCT coefficients for the quantizing circuit, when the block image is in the flat state.