Vb .net Sharpen Image Function

Sharpening an image consists of highlighting the edges of the objects. Edges are areas of an image with sharp changes in intensity between adjacent pixels. If the pixels are on an edge, the difference between two adjecent pixels will be a large value (maybe negative). This will be an area of the image with some degree of detail that can be sharpened. If the difference is low or zero the two pixels are nearly identical. This is called a "Flat" area of the image. How to bring out the details without leveling the rest of the image. If we add the difference to the original pixel we will have little change were the image is flat and a much higher sharper change.

Sharpening Algorithum NewValue = OldValue + 0.5 *difference.

Note if you simply add the difference to the original pixel, you get too much detail

Function SharpenImage(ByVal image As Image) As Image Dim tempimage As New Bitmap(image) Dim dx As Integer = 1 Dim dy As Integer = 1 Dim red, green, blue As Integer Dim bmp As Bitmap Dim I, J As Integer tempimage = image bmp = image With tempimage For I = dx To .Height - dx - 1 For J = dy To .Width - dy - 1 red = CInt(.GetPixel(J, I).R + 0.05 * CInt(.GetPixel(J, I).R - CInt(.GetPixel(J - dx, I - dy).R))) green = CInt(.GetPixel(J, I).G + 0.05 * CInt(.GetPixel(J, I).G - CInt(.GetPixel(J - dx, I - dy).G))) blue = CInt(.GetPixel(J, I).B + 0.05 * CInt(.GetPixel(J, I).B - CInt(.GetPixel(J - dx, I - dy).B))) red = Math.Min(Math.Max(red, 0), 255) green = Math.Min(Math.Max(green, 0), 255) blue = Math.Min(Math.Max(blue, 0), 255) bmp.SetPixel(J, I, Color.FromArgb(red, green, blue)) Next Next End With Return bmp End Function

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