INNOVATIVE IMAGE PROCESSING IN CHARGED PARTICLE MICROSCOPY

A method of using a charged particle microscope comprising: - A source, for producing a beam of charged particles; - A specimen holder, for holding a specimen; - An illuminator, for irradiating said specimen with said charged particles; - A detector, for detecting radiation emanating from the specimen in response to said irradiation; - A controller, for controlling at least some aspects of the microscope's operation, which method comprises the steps of: - Using said detector to acquire a successive series of component images {I 1 ,..., I n ,..., I N } of a given part of the specimen; - Combining said component images so as to assemble a composite image, further comprising the following steps, executed prior to said combining step: - Successively quantizing each component image, and storing it in a memory; - Recording a quantization error per pixel for each quantized component image, and keeping a running tally T n of cumulative quantization error per pixel for quantized component images {I 1 ,..., I n }; - When quantizing a next component image I n+1 , for a given pixel, choosing a quantization polarity that will tend to avoid further increasing T n+1 relative to T n , such that: –ª If T n is positive, then T n+1 will be less positive; –ª If T n is negative, then T n+1 will be less negative; –ª If T n is zero, then T n+1 is allowed to be positive, negative or zero.