WAVELET CONVERTER, ITS METHOD, WAVELET INVERSE CONVERTER, ITS METHOD, IMAGE CODER, ITS METHOD, IMAGE DECODER AND ITS METHOD

摘要

PROBLEM TO BE SOLVED: To reduce a work memory considerably or to eliminate the memory and to maintain the image quality to a level attained by provision of a discrete cosine transform DCT. SOLUTION: The wavelet converter or the like is provided with a low frequency component extract means 12 that extracts a low frequency component from an input signal and a high frequency component extract means 13 that, extracts a high frequency component from the input signal, and also with a prediction value generating means 16 that produces a prediction value used to predict the high frequency component and with a subtractor means 18 that subtracts the predicted value from the high frequency component, the subtractor means 18 provides a new high frequency component, outputs the new high frequency component and the prediction value generating means 16 uses extraporation prediction or interpolation prediction properly to generate the prediction value. Furthermore, the input, signal is divided into prescribed blocks, and in the case that the prediction for generating the predicted value bridges over the blocks, extraporation prediction is conducted, and in the case that the prediction for generating the predicted value does not bridge over the blocks, interpolation prediction is conducted. Furthermore, it is preferable to set an upper limit and a lower limit to the predicted value by the extraporation prediction. Furthermore, the predicted value is generated by inverse algorithm in the inverse conversion and used.