A head up display device comprising: a display unit configured to display a display image; a detection unit configured to detect two-dimensional pixel distribution data regarding chromaticity and brightness of a non-background region outside a region that is superimposed on the display image; and a transformation unit configured to: determine a chromaticity coordinate range of the non-background region based on the detected two-dimensional distribution data, and transform a first chromaticity of the display image into a second chromaticity outside the determined chromaticity coordinate range when the first chromaticity of the display image is within the determined chromaticity coordinate range; wherein the transformation unit is configured to: divide the detected range of the two-dimensional distribution data in to a plurality of areas; determine chromaticity coordinate ranges of the plurality of areas; select a chromaticity coordinate range common between the plurality of areas from among the determined chromaticity coordinate ranges; and transform the first chromaticity to the second chromaticity based on the selected chromaticity coordinate range common between the plurality of areas. a display unit configured to display a display image; a detection unit configured to detect two-dimensional pixel distribution data regarding chromaticity and brightness of a non-background region outside a region that is superimposed on the display image; and a transformation unit configured to: determine a chromaticity coordinate range of the non-background region based on the detected two-dimensional distribution data, and transform a first chromaticity of the display image into a second chromaticity outside the determined chromaticity coordinate range when the first chromaticity of the display image is within the determined chromaticity coordinate range; wherein the transformation unit is configured to: divide the detected range of the two-dimensional distribution data in to a plurality of areas; determine chromaticity coordinate ranges of the plurality of areas; select a chromaticity coordinate range common between the plurality of areas from among the determined chromaticity coordinate ranges; and transform the first chromaticity to the second chromaticity based on the selected chromaticity coordinate range common between the plurality of areas. determine a chromaticity coordinate range of the non-background region based on the detected two-dimensional distribution data, and transform a first chromaticity of the display image into a second chromaticity outside the determined chromaticity coordinate range when the first chromaticity of the display image is within the determined chromaticity coordinate range; wherein the transformation unit is configured to: divide the detected range of the two-dimensional distribution data in to a plurality of areas; determine chromaticity coordinate ranges of the plurality of areas; select a chromaticity coordinate range common between the plurality of areas from among the determined chromaticity coordinate ranges; and transform the first chromaticity to the second chromaticity based on the selected chromaticity coordinate range common between the plurality of areas. divide the detected range of the two-dimensional distribution data in to a plurality of areas; determine chromaticity coordinate ranges of the plurality of areas; select a chromaticity coordinate range common between the plurality of areas from among the determined chromaticity coordinate ranges; and transform the first chromaticity to the second chromaticity based on the selected chromaticity coordinate range common between the plurality of areas.