A smaller anomaly visible in both the average - and the standard deviation image is marked by another white arrow.
In the cryo-EM example detailed in Figure 1, bad image areas can be discerned directly in the raw images (Fig. 1a,b) but especially in the average image (Fig. 1c) and the standard deviation image (σ-image, Fig. 1d).
where the corrected image intensity is derived from the measured raw image by subtracting, the average image over the full large dataset, normalized by the standard deviation image of that dataset (dimensionless units are used throughout).
where the corrected image intensity is derived from the measured raw image, by subtracting, the average image over the full large dataset, normalized by the standard deviation image of that dataset.
Specifically, represents the foreground masks, denotes the sample frames, represents the background image, and is the standard deviation image, with denoting pixel position within the image (1).
The diversity enhancement technique proposed, based on the segmentation of the local standard deviation image obtained at the output of the first stage, is more general.
Most quality metrics measure variation in physical image properties only (e.g., pixel deviation, image intensity, contrast), without consideration for the impact of those properties on perception and/or decision.
The filtered (standard deviation) image is then normalized (via pixel wise division) by the mean image, which is also computed by replacing each pixel by the mean value of pixels in a local window around the pixel.
Information across the entire division video is combined by calculating the pixel-by-pixel standard deviation image.
