Adaptive Threshold is a better way to convert color or grayscale images to black-and-white (binary). It would be really nice to have in IrfanView for processing photos/scans of documents and books where the lighting was uneven. Specifically, adaptive thresholding decides whether to make a particular pixel black or white based on the local area around the pixel. In contrast, the current "global" thresholding method compares with the average over the whole image. ImageMagick supports adaptive thresholding with their -lat switch). It's the one and only thing I use ImageMagick for. Otherwise, I use IrfanView.
Here's an example from this academic page on adaptive thresholding.
Original image:
Global thresholding:
Adaptive thresholding (requested):
(Credit: R. Fisher, S. Perkins, A. Walker and E. Wolfart. at University of Edinborough School of Informatics)
Here's an example from this academic page on adaptive thresholding.
Original image:
Global thresholding:
Adaptive thresholding (requested):
(Credit: R. Fisher, S. Perkins, A. Walker and E. Wolfart. at University of Edinborough School of Informatics)
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