When the JPEG (Joint Photographic Experts Group) compression algorithm compresses image with high compression rate, the false contour and mosquito noise that do not exist in an original image appear in a compression restoration image. It is well known that this trend is remarkable in artificial images (e.g. computer graphics) by comparison with natural images. A human being feels false contour to an eyesore. Also, false contour is influenced by the accuracy of the devices that outputs an image. False contour is conspicuous in the case that it used the high accuracy output devices, although it is not conspicuous in the case that it used the low accuracy noisy output devices.In this research, we studied it from both sides of compression rate and the accuracy of output devices about the condition that false contour becomes eyesore.