Patent ID: 8325993

Claim:
A method, comprising: determining that a digital image contains a biometric identifier; dividing the digital image into a grid of blocks; computing a ridge orientation for each block containing a portion of the biometric identifier in the grid of blocks; determining a bad block in the grid of blocks by applying a bad block heuristic, the bad block heuristic comparing the computed ridge orientation for each block containing the portion of the biometric identifier in the grid of blocks as a target block to the ridge orientation for each block directly adjacent to the target block and identifying the target block as a bad block if a deviation between the ridge orientation of the target block and ridge orientations of the directly adjacent blocks exceeds a certain threshold; executing lighting compensation to remove a lighting effect from the biometric identifier, the lighting compensation being a piece-wise linear transformation of a light intensity for each block of the digital image that calculates an intensity height field of the each block in the grid of blocks and fits a separate plane to the calculated intensity height field for the each block; processing the biometric identifier ignoring the identified bad blocks and after the lighting compensation is executed to create an identification profile; and outputting the created identification profile in a format usable by a user.