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I am processing an image using lockbits and I need to compare pixels with surrounding ones and change them according to the results of the comparison.
My approach is to move simultaneously on two images or bitmapdatas, and make the changes on the second image. This way the changes made won't affect the results of the comparisons on the first one. How do I increase both pointers by the same amount?
The problem I encounter is that I get past the limit of the array bounds. If I manually set the limits to a much smaller amount, I can process the images, but I get a dotted skewed image that shows 3 silhouetes side by side. Something similar to an analog TV set that has the verical and horizontal scans out of synch. I suspect that the pointers are the cause.
Here is my code:
Private Sub Button8_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
Dim Tol As Integer = CInt(2.5 * TrackBar2.Value)
Try
Dim rect As Rectangle = Rectangle.Round(PictureBox1.Image.GetBounds(GraphicsUnit.Pixel))
Dim wid As Integer = PictureBox1.Image.Width
Dim hgt As Integer = PictureBox1.Image.Height
Dim img As New Bitmap(wid, hgt)
img = WorkImg
Dim img1 As New Bitmap(wid, hgt)
img1 = PictureBox1.Image 'WorkImg
Dim bmpSr As BitmapData = img.LockBits(New Rectangle(0, 0, img.Width, img.Height), ImageLockMode.ReadWrite, img.PixelFormat)
Dim bmpRes As BitmapData = img1.LockBits(New Rectangle(0, 0, img1.Width, img1.Height), ImageLockMode.ReadWrite, img1.PixelFormat)
Dim ptrSr As IntPtr = bmpSr.Scan0
Dim ptrRes As IntPtr = bmpRes.Scan0
Dim R, G, B As Integer
R = 1
G = 2
B = 3
Dim bytesSr As Integer = bmpSr.Stride * img.Height
Dim bytesRes As Integer = bmpRes.Stride * img1.Height
Dim rgbvaluesSr(bytesSr) As Byte
Dim rgbvaluesRes(bytesRes) As Byte
System.Runtime.InteropServices.Marshal.Copy(ptrSr, rgbvaluesSr, 0, bytesSr)
System.Runtime.InteropServices.Marshal.Copy(ptrRes, rgbvaluesRes, 0, bytesRes)
For i As Integer = (bmpSr.Stride - 1) To img.Width * (img.Height - 20) Step 4 'Here Hardcoded values to test
If (Math.Max(rgbvaluesSr(i + R), rgbvaluesSr(i + 4 + R)) - Math.Min(rgbvaluesSr(i + R), rgbvaluesSr(i + 4 + R))) > NRed.Value Or _
(Math.Max(rgbvaluesSr(i + G), rgbvaluesSr(i + 4 + G)) - Math.Min(rgbvaluesSr(i + G), rgbvaluesSr(i + 4 + G))) > NGreen.Value Or _
(Math.Max(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + 4 + B)/>) - Math.Min(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + 4 + B)/>)) > NBlue.Value Or _
(Math.Max(rgbvaluesSr(i + R), rgbvaluesSr(i + R + bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + R), rgbvaluesSr(i + R + bmpSr.Stride))) > NRed.Value Or _
(Math.Max(rgbvaluesSr(i + G), rgbvaluesSr(i + G + bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + G), rgbvaluesSr(i + G + bmpSr.Stride))) > NGreen.Value Or _
(Math.Max(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + B + bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + B + bmpSr.Stride))) > NBlue.Value Or _
(Math.Max(rgbvaluesSr(i + R), rgbvaluesSr(i + 4 + R + bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + R), rgbvaluesSr(i + 4 + R + bmpSr.Stride))) > NRed.Value Or _
(Math.Max(rgbvaluesSr(i + G), rgbvaluesSr(i + 4 + G + bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + G), rgbvaluesSr(i + 4 + G + bmpSr.Stride))) > NGreen.Value Or _
(Math.Max(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + 4 + B + bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + 4 + B + bmpSr.Stride))) > NBlue.Value Or _
(Math.Max(rgbvaluesSr(i + R), rgbvaluesSr(i + 4 + R - bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + R), rgbvaluesSr(i + 4 + R - bmpSr.Stride))) > NRed.Value Or _
(Math.Max(rgbvaluesSr(i + G), rgbvaluesSr(i + 4 + G - bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + G), rgbvaluesSr(i + 4 + G - bmpSr.Stride))) > NGreen.Value Or _
(Math.Max(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + 4 + B - bmpSr.Stride)) - Math.Min(rgbvaluesSr(i + B)/>, rgbvaluesSr(i + 4 + B - bmpSr.Stride))) > NBlue.Value Or _
(CInt(rgbvaluesSr(i + R) / 3 + rgbvaluesSr(i + G) / 3 + rgbvaluesSr(i + B)/> / 3) - CInt(rgbvaluesSr(i + 4 + R) / 3 + rgbvaluesSr(i + 4 + G) / 3 + rgbvaluesSr(i + 4 + B)/>) / 3) = Tol Or _
(CInt(rgbvaluesSr(i + R) / 3 + rgbvaluesSr(i + G) / 3 + rgbvaluesSr(i + B)/> / 3) - CInt(rgbvaluesSr(i + 4 + R + bmpSr.Stride) / 3 + rgbvaluesSr(i + 4 + G + bmpSr.Stride) / 3 + rgbvaluesSr(i + 4 + B + bmpSr.Stride) / 3) = Tol Or _
(CInt(rgbvaluesSr(i + R) / 3 + rgbvaluesSr(i + G) / 3 + rgbvaluesSr(i + B)/> / 3) - CInt(rgbvaluesSr(i + 4 + R + bmpSr.Stride) / 3 + rgbvaluesSr(i + 4 + G + bmpSr.Stride) / 3 + rgbvaluesSr(i + 4 + B + bmpSr.Stride) / 3) = Tol)) Then
rgbvaluesRes(i) = 255
rgbvaluesRes(i + R) = 0
rgbvaluesRes(i + G) = 0
rgbvaluesRes(i + B)/> = 0
Else
rgbvaluesRes(i) = 255
rgbvaluesRes(i + R) = 255
rgbvaluesRes(i + G) = 255
rgbvaluesRes(i + B)/> = 255
End If
Next
System.Runtime.InteropServices.Marshal.Copy(rgbvaluesRes, 1000, ptrRes, bytesRes)'Here Harcoded value to test
img.UnlockBits(bmpSr)
img1.UnlockBits(bmpSr)
PictureBox1.Image = img1
PictureBox1.Invalidate()
Dim bmpFromImage As New Bitmap(PictureBox1.Width, PictureBox1.Height)
bmpFromImage = PictureBox1.Image
Dim g1 As Graphics = Graphics.FromImage(img1)
g1.DrawImage(bmpFromImage, 0, 0, img1.Width, img1.Height)
g1.Dispose()
Catch ex As Exception
MessageBox.Show("NoImage To Process")
End Try
End Sub
I have a similar subroutine with only one image, but it won't detect slanted down lines, so I want to compare pixels with the ones above to the right.
I am just starting to figure out Lockbits and I don't know how to go about it. Any directions on this regard will be really appreciated.
Regards,
ricardosms
This post has been edited by ricardosms: 02 May 2011 - 08:32 AM
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