Method and apparatus for image analysis

A non-transitory computer program product comprising machine-readable instructions therein, the instructions, upon execution by a computer processor system, configured to cause the computer processor system to at least:

• evolve a curve enclosing an object subject to constraints of the object, the object, representing a lithographically created structure, of an image from a SEM or optical inspection apparatus;
• terminate evolution of the curve when an area enclosed by the curve reaches to, or near, the boundary of the object;
• and
• obtain a numerical function upon termination of the evolution of the curve, wherein the numerical function is configured for a classification of a defect, for an estimation of a defect, for a monitoring of a process, and/or for a controlling of a process.

A non-transitory computer program product comprising machine-readable instructions therein, the instructions, upon execution by a computer processor system, configured to cause the computer processor system to at least:

• process a noisy SEM or optical inspection image containing an object representing a lithographically created structure, by:
• evolution of a curve enclosing the object subject to constraints of the object, or
• application of a level set method to the object such that a curve is evolved relative to the object subject to constraints of the object;
• and
• obtain a high resolution mathematical representation or numerical function corresponding to the structure upon termination of evolution of the curve, wherein the mathematical representation or numerical function is configured for a classification of a defect, for an estimation of a defect, for a monitoring of a process, and/or for a controlling of a process.