The Orthogonal Transform Sign

The nature of transform signs in typical real orthogonal transforms are presented. Phase-only synthesis is intro- duced by ”Image recovery -Theory and Application-” written by Henry Stark. Sign-only synthesis is the ex- tended version of the Phase-only synthesis. Sign-only synthesis is defined as an inverse transform of only signs of the transform coefficients and has interesting prop- erty in its applications. Orthogonal transforms taken in this paper are Discrete Cosine Transform, Hadamard transform, Fourier Transform with binarized phase and Karhunen-Loeve Transform. These transforms have real number coefficients and then it looks interesting to know the property of each transform signs. The character- istics of these Sign-only synthesis are compared each other. And interesting nature of transform signs are ex- tended. One application of Sign-only synthesis is shown as a facial authentication.