| 摘要 |
A method and apparatus for deriving a hash value from a single channel image, comprising: size reducing ( S21 ) the image into a series of first resized images having different horizontal and vertical size, deriving ( S22 ) from each first resized image a horizontal difference image comprising horizontal neighboring pixel differences, size reducing ( S31 ) the image into a sequence of second resized images having different horizontal and vertical size, deriving ( S32 ) from each second resized image a vertical difference image comprising vertical neighboring pixel differences, and combining ( S4 , S5 ) the sign bits of the horizontal neighboring pixel differences and the sign bits of the vertical neighboring pixel differences in a predefined order into bits of the hash value. |
