Compression of image information in electron images

Abstract Image compression for electron imaging is considered by the method of transform coding using the discrete cosine transform and an adaptive method. Using examples drawn from conventional transmission microscopy, data compression by at least 10 to 12 times (from the original 8 bits per pixel image) and sometimes 20 to 30 times is shown to give acceptable image quality. A modification for electron images is necessary to published procedures of sub-image classification within the adaptive procedure. This is because of the nature of the spatial frequency spectra of electron images. On average, the action of data compression is shown to be analogous to the action of a point spread function for the images chosen for study.