Abstract
Human visual sense has two aspects in our feeling for blurred image, that is, one is the amount of blur depending on object size, the other is the amount of blur independent of the object size. In the former for example, when the image size becomes larger, we feel smaller amount blur. The quantitative evaluation based on entropy for blurred images is proposed in this paper. The author calls this metric "variation entropy". This metric has two kinds of aspects that coincide with the human visual sense. The first is the absolute evaluation of blur, and the second is the relative evaluation of blur. The former can be quantified by "variation entropy for a unit boundary length (or L-type variation entropy: H^L)", which is dependent on resolution, and the latter can be quantified by "variation entropy for a unit area (or A-type variation entropy: H^A)", which is independent of resolution. These two metrics have complementary properties. Last, two variation entropies are applied to the standard kanji character database, and then the strong relation between variation entropy and accuracy of recognition is discussed.
