| CPC H01J 37/28 (2013.01) [G06T 5/50 (2013.01); G06V 10/28 (2022.01); G06T 2207/10061 (2013.01); G06T 2207/20221 (2013.01)] | 5 Claims |
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1. An electron microscope comprising:
an electronic optical system that irradiates a specimen with an electron beam and forms an image using electrons transmitted through the specimen;
a camera that comprises an image sensor and outputs a frame image which is based on a signal obtained by electrons entering each cell of the image sensor; and
a computation unit that generates an image based on the frame image,
the computation unit performing processing for:
setting a threshold; and
binarizing the frame image using the threshold, and generating the image based on the binarized frame image, and
in the processing for setting the threshold,
the computation unit repeatedly performing processing for (i) setting a tentative threshold, (ii) acquiring a plurality of the frame images obtained on a condition that electrons entering the image sensor follow Poisson process, (iii) binarizing each of the plurality of acquired frame images using the tentative threshold, (iv) generating an integrated image by integrating the plurality of binarized frame images, and (v) obtaining a normalized constant based on a mean and variance of pixel values of pixels of the integrated image, with the tentative threshold being differed each time of the processing, and
the computation unit obtaining an optimal threshold based on the plurality of obtained normalized constants and setting the optimal threshold as the threshold.
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