Normal Pixelate
The algorithm processes an image creating the effect of an image with larger pixels.
Public Shared Sub ApplyNormalPixelate(ByRef bmp As Bitmap, squareSize As Size)
Dim TempBmp As Bitmap = DirectCast(bmp.Clone(), Bitmap)
Dim bmpData As BitmapData = bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb)
Dim TempBmpData As BitmapData = TempBmp.LockBits(New Rectangle(0, 0, TempBmp.Width, TempBmp.Height), ImageLockMode.[ReadOnly], PixelFormat.Format24bppRgb)
Dim ptr As IntPtr = bmpData.Scan0
Dim TempPtr As IntPtr = TempBmpData.Scan0
Dim stopAddress As Integer = CInt(ptr) + bmpData.Stride * bmpData.Height
Dim Val As Integer = 0
Dim i As Integer = 0, X As Integer = 0, Y As Integer = 0
Dim BmpStride As Integer = bmpData.Stride
Dim BmpWidth As Integer = bmp.Width
Dim BmpHeight As Integer = bmp.Height
Dim SqrWidth As Integer = squareSize.Width
Dim SqrHeight As Integer = squareSize.Height
Dim XVal As Integer = 0, YVal As Integer = 0
While CInt(ptr) <> stopAddress
X = i Mod BmpWidth
Y = i \ BmpWidth
XVal = X + (SqrWidth - X Mod SqrWidth)
YVal = Y + (SqrHeight - Y Mod SqrHeight)
If XVal < 0 AndAlso XVal >= BmpWidth Then
XVal = 0
End If
If YVal < 0 AndAlso YVal >= BmpHeight Then
YVal = 0
End If
If XVal > 0 AndAlso XVal < BmpWidth AndAlso YVal > 0 AndAlso YVal < BmpHeight Then
Val = (YVal * BmpStride) + (XVal * 3)
Marshal.WriteByte(ptr + 0, Marshal.ReadByte(TempPtr + Val))
Marshal.WriteByte(ptr + 1, Marshal.ReadByte(TempPtr + Val + 1))
Marshal.WriteByte(ptr + 2, Marshal.ReadByte(TempPtr + Val + 2))
End If
ptr += 3
i += 1
End While
bmp.UnlockBits(bmpData)
TempBmp.UnlockBits(TempBmpData)
End Sub
Example
DIm b As Bitmap = CType(Image.FromFile("rose.jpg"), Bitmap)
ApplyNormalPixelate(b, new Size(15, 15))