PURPOSE: To stably set and display a density image at an extensive density level and in range by setting the density level and range to two steps.

CONSTITUTION: A 1st density range setting means 6a inputs the 1st density level and range of the displayed density image from 1st level and range input means 7a and 8a, generates and outputs density range data to a density range conversion means 2, and rewrites data in a density range table. A 2nd density range setting means 6b inputs the 2nd density level and range from 2nd level and range input means 7b and 8b, generates and outputs luminance data to a density and luminance conversion means 3, and rewrites the data in a density and luminance table, so that the display density level and range are set to two steps. Thus, the density level of the displayed density image and the density display range based on the density level thereof are stably set and displayed extensively from a narrow range to a wide range.