Patent ID: 8807762

Claim:
A projector, comprising: a projection unit that projects a projection image; a detection unit that detects a condition at a projection surface by using a photographic image of the projection surface upon which a specific projection image is projected via the projection unit; a decision-making unit that makes a decision based upon the condition at the projection surface as to whether or not the projection surface is suitable for projection; and a decision-making result reporting unit that reports results of the decision made by the decision-making unit to a user, wherein: based upon a reflectance threshold value R i (i=1, 2, . . . N) assuming a plurality of predetermined values and a pixel ratio threshold value C i (i=1, 2, . . . N) assuming a plurality of predetermined values, the decision-making unit extracts pixels indicating brightness values smaller than a product obtained by multiplying a largest brightness value in the photographic image by the reflectance threshold value R i among pixels constituting the photographic image, and determines that the projection surface is suitable for projection if a ratio of the extracted pixels to the pixels constituting the photographic image is less than the pixel ratio threshold value C i for all values taken for i, (i=1, 2, . . . N); and a reflectance threshold value R j assumed when i=j (j=1, 2, . . . N −1) is smaller than a reflectance threshold value R j+1 assumed when i=j +1 and a pixel ratio threshold value C j assumed when i=j (j=1, 2, . . . N −1) is smaller than a pixel ratio threshold value C j+1 assumed when i=j +1.