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Practical Methods for Digital Image Enhancement in SEM

1994; Oxford University Press; Linguagem: Inglês

10.1093/oxfordjournals.jmicro.a051116

1477-9986

Eisaku Oho, Klaus‐Ruediger Peters,

Advanced Electron Microscopy Techniques and Applications

In microscopy, the most important image information is found in image details, i.e., the smallest image features. As an initial step in image detail evaluation, the whole image must be surveyed for relevant information. Then, identified features may be further inspected. Two tasks must be accomplished in a first approach to full-frame image evaluation: the overall contrast must be balanced for assessment of large image features, and the local contrasts must be enhanced for assessment of detail features. A new automatic “highlight” filter proved very useful for the achievement of both tasks. The filter makes it possible to visually access the image detail content immediately after image acquisition and thus facilitates microscopy on difficult samples. The digital filter operates automatically without the need for specific parameters under normal operating conditions. A median filter with an unusually large mask size is used for the extraction of detail contrasts characterized as highlight contrast, and histogram equalization is used for the enhancement of the highlight contrasts. The processing utilizes digital signal processors for high-speed image enhancement facilitating visual analysis of the improved image. The filter's performance is compared with that of conventional processing techniques and microscopic image acquisition under varied conditions. The highlight filter facilitates immediate assessment of image detail content and contrast mechanisms, and thus improves routine microscopy.