Comparing objective and subjective error measures for color constancy

An electronic parts casing which can be easily formed, which allows a reduction in size and which resists deformation. The electronic parts casing is composed of a frame member, an inner cover and an outer cover, and is divided into two chambers by a partition provided inside the frame member. On the outer side surfaces of the frame member, there are provided ridges for the engagement of the outer cover, and, in the periphery of the outer cover, there are provided detents to be engaged with the outer ridges of the frame member. On the top surface of the inner cover, there are provided outwardly convex draw surfaces, and, on the top surface of the outer cover, there is provided an outwardly convex draw portion, which has on its inner side an inwardly convex draw surface. The inner cover is placed in contact with the upper edges of the inner cover and of the partition. The convex draw surfaces provided on the inner cover are brought into close contact with the convex draw surface provided on the outer cover, and the detents of the outer cover are engaged with the ridges of the frame member to thereby cause the outer cover to be engaged with and fixed to the frame member.