Patent ID: 8538182

Claim:
An image data decoding device comprising: an image processing circuit configured to act as: a determination unit that receives compressed image data including information of one DC component, information of frequency components other than the DC component and a block end code for each block of an image as a result of frequency analysis of pixel values in each of the blocks and that determines each of the blocks of the received compressed image data sequentially in order from a head block of the blocks as to whether the block consists of: 1) the DC component, at least one AC component and the block end code or 2) the DC component and the block end code without any AC components; a first pixel value generating unit that performs inverse operation to the frequency analysis on the DC component and the frequency components other than the DC component included in each block so as to generate pixel values of the block when the block is determined as consisting of the DC component, at least one AC component and the block end code by the determination unit; and a second pixel value generating unit that generates one and the same pixel value for all pixels of each block based on information of the DC component when the block is determined as consisting of the DC component and a block end code without any AC components by the determination unit.