Dr Jean-François Parrot
PINS function was developed to ensure a stretching of the dynamic range of gray tones of an image that is not limited to a single normalization between 0 and 255 of the original scale generating spaces between the new positions of the gray tone values. The acronym Pins in French means "To inhibit the Stretching concept" that is to say to stretch in another way the gray tone values. This means that all values are recalculated on the scale 0, 255 to avoid creating any gap between the new gray tone values.
The process is as follows: in a moving window of 3 × 3 and according to the instructions of the user the program sums the values of the central pixel and its neighbor four cardinal directions (North, East, South and West) or calculates the sum of the central pixel and its 8 neighbors. This amount is reported on the pixel under consideration and an image of 2 bytes is obtained whose dynamics is further normalized between 0 and 255 (grayscale image) according to the minimum and the maximum value found in the 2 bytes image.
J.-F. Parrot, Mexico 2010
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