Abstract: Methods and systems for determining information for a specimen are provided. One system includes a computer subsystem configured for removing one or more patterns in a specimen image that do not touch a defect detected in the specimen image thereby generating a modified specimen image. The computer subsystem is also configured for generating one or more hash codes for the modified specimen image. In addition, the computer subsystem is configured for assigning the specimen image to one of multiple groups based on a distance between the one or more hash codes and one or more other hash codes generated for a second modified specimen image generated for a second specimen image.

Abstract: A method for phase unwrapping is provided. The method may include obtaining an initial phase image including a plurality of phase elements. At least one of the phase elements may be wrapped. The method may also include generating a phase mask by preprocessing the initial phase image based on phase differences between the plurality of phase elements. The method may also include generating at least two segmental phase images by segmenting the initial phase image along at least two directions based on the phase mask. The method may further include generating at least two intermediate phase images by performing phase unwrapping on each of the at least two segmental phase images, respectively. The method may further include determining an unwrapped phase image corresponding to the initial phase image based on the at least two intermediate phase images.

Abstract: A method for phase unwrapping is provided. The method may include obtaining an initial phase image including a plurality of phase elements. At least one of the phase elements may be wrapped. The method may also include generating a phase mask by preprocessing the initial phase image based on phase differences between the plurality of phase elements. The method may also include generating at least two segmental phase images by segmenting the initial phase image along at least two directions based on the phase mask. The method may further include generating at least two intermediate phase images by performing phase unwrapping on each of the at least two segmental phase images, respectively. The method may further include determining an unwrapped phase image corresponding to the initial phase image based on the at least two intermediate phase images.