Abstract
With recent advances in high dynamic range displays, high-gradation displays have been actively studied. The suitable gradation number for a luminance range of a display is not obvious. We had researched about the relationship between the gradation number and the displayed image to find the suitable gradation number for the luminance range of a usual display. We found if the gradation area of the displayed image was more than 50%, the gradation number more than 8 bit was suitable. However, if it is less than 50%, we could not tell any effects of increasing the gradation number.
