Processing poor quality line drawings by local estimation of noise
The problem of extracting the best data from poor quality line originals at the lowest possible resolution is considered. The form of the grey level histogram from such originals is examined, especially the shape of the peak corresponding to the white background. The viability of deriving a threshold for display from simple measurements of the location and width of this peak is demonstrated. A more accurate method for these measurements is described, and the improvement in thresholding upon its application to originals with variations in background noise level across the image is shown. The accuracy of the methods is quantified.
KeywordsGrey Level Black Pixel Background Noise Level Noise Standard Deviation Grey Level Histogram
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