An image coding device for coding an input image of multi-level. In the image coding device, an input multi-level image is analyzed by an image analyzing portion, and update information to be used when a probability estimation value is generated is generated by an update value determining portion on the basis of adjoining pixel information as a result of the analysis by the image analyzing portion. Further, a probability estimation value is generated by a probability estimating portion on the basis of the update information generated by the update value determining portion and the result of the analysis by the image analyzing portion, and the input multi-level image is arithmetically coded by a code word generating portion on the basis of the probability estimation value generated by the probability estimating portion.
Image coding/decoding device