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    <p>I've played around a bit and thought that using something like the KMP algorithm (that's an easy one to implement I guess -> wikipedia has a nice pseudocode) might be helpfull too:</p> <pre><code>Imports System.Drawing.Imaging Imports System.Runtime.InteropServices Public Class ImageFinder Public Shared Function Contains(Parent As Bitmap, Child As Bitmap) As Point If Parent Is Nothing OrElse Child Is Nothing Then Throw New ArgumentException("Narf!") If Parent.PixelFormat &lt;&gt; Imaging.PixelFormat.Format32bppArgb OrElse Child.PixelFormat &lt;&gt; Imaging.PixelFormat.Format32bppArgb Then Throw New ArgumentException("Narf again!") If Parent.Width = Child.Width AndAlso Parent.Height = Child.Height AndAlso Parent.GetPixel(0, 0) &lt;&gt; Child.GetPixel(0, 0) Then Return Nothing If Child.Width &gt; Parent.Width OrElse Child.Height &gt; Parent.Height Then Return Nothing Dim bmdParent, bmdChild As BitmapData Try ' Get bitmap data into array of int bmdParent = Parent.LockBits(New Rectangle(0, 0, Parent.Width, Parent.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb) bmdChild = Child.LockBits(New Rectangle(0, 0, Child.Width, Child.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb) Dim ParentValuesPerLine As Integer = bmdParent.Stride \ 4 Dim ChildValuesPerLine As Integer = bmdChild.Stride \ 4 Dim ParentData((bmdParent.Stride \ 4) * bmdParent.Height - 1) As Integer Dim ChildData((bmdChild.Stride \ 4) * bmdChild.Height - 1) As Integer Marshal.Copy(bmdParent.Scan0, ParentData, 0, ParentData.Length) Marshal.Copy(bmdChild.Scan0, ChildData, 0, ChildData.Length) If bmdParent IsNot Nothing Then Parent.UnlockBits(bmdParent) bmdParent = Nothing If bmdChild IsNot Nothing Then Child.UnlockBits(bmdChild) bmdChild = Nothing ' Create KMP-Table: Dim T(Child.Height - 1)() As Integer For i = 0 To Child.Height - 1 T(i) = KMP_Table(ChildData, i * ChildValuesPerLine, ChildValuesPerLine) Next Dim line_c As Integer = 0 Dim line_p As Integer = 0 Dim found As Boolean While line_p &lt;= Parent.Height - Child.Height line_c = 0 Dim childoffset As Integer = line_c * ChildValuesPerLine Dim parentoffset As Integer = line_p * ParentValuesPerLine Dim m As Integer = -1 While True m = KMP_Search(ParentData, parentoffset, ParentValuesPerLine, m + 1, ChildData, 0, ChildValuesPerLine, T(0)) If m &gt; -1 Then ' first line found Debug.Print("Possible match at {0},{1}", m, line_p) found = True Dim p = parentoffset + ParentValuesPerLine Dim c = childoffset + ChildValuesPerLine For i = 1 To Child.Height - 1 If KMP_Search(ParentData, p, ParentValuesPerLine, m, ChildData, childoffset, ChildValuesPerLine, T(i)) &lt;&gt; m Then ' this line doesnt match found = False Exit For End If p += ParentValuesPerLine c += ChildValuesPerLine Next If found Then Debug.Print("Found match at {0},{1}", m, line_p) Return New Point(m, line_p) End If Else Exit While End If End While line_p += 1 End While 'Catch ex As Exception 'Throw Finally If bmdParent IsNot Nothing Then Parent.UnlockBits(bmdParent) If bmdChild IsNot Nothing Then Child.UnlockBits(bmdChild) End Try End Function Private Shared Function KMP_Search(ByVal S As Integer(), s0 As Integer, slen As Integer, m As Integer, ByVal W As Integer(), w0 As Integer, wlen As Integer, tbl() As Integer) As Integer Dim i As Integer = 0 While m + i &lt; slen If W(w0 + i) = S(s0 + m + i) Then If i = wlen - 1 Then Return m i += 1 Else m = m + i - tbl(i) If tbl(i) &gt; -1 Then i = tbl(i) Else i = 0 End If End If End While Return -1 End Function Private Shared Function KMP_Table(ByRef arr() As Integer, start As Integer, count As Integer) As Integer() Dim table(count - 1) As Integer table(0) = -1 table(1) = 0 Dim pos As Integer = 2 Dim cnd As Integer = 0 While pos &lt; count - 1 If arr(start + pos - 1) = arr(start + cnd) Then cnd += 1 table(pos) = cnd pos += 1 ElseIf cnd &gt; 0 Then cnd = table(cnd) Else table(pos) = 0 pos += 1 End If End While Return table End Function End Class </code></pre> <p>I used the following "benchmark" function to compare against the code from <strong>Abdias Software</strong> :</p> <pre><code>Private Sub Button1_Click_1(sender As Object, e As EventArgs) Handles Button1.Click Dim ofd As New OpenFileDialog If ofd.ShowDialog = Windows.Forms.DialogResult.OK Then Dim bm As Bitmap = Bitmap.FromStream(New MemoryStream(File.ReadAllBytes(ofd.FileName))) Dim bm2 As New Bitmap(bm.Width, bm.Height, PixelFormat.Format32bppArgb) Dim gr = Graphics.FromImage(bm2) gr.DrawImageUnscaled(bm, New Point(0, 0)) Dim bm3 As New Bitmap(100, 100, PixelFormat.Format32bppArgb) gr = Graphics.FromImage(bm3) gr.DrawImage(bm2, New Rectangle(0, 0, 100, 100), New Rectangle(bm2.Width - 110, bm2.Height - 110, 100, 100), GraphicsUnit.Pixel) PictureBox1.Image = bm3 Dim res As New List(Of Integer) For i = 1 To 10 Dim stp = Stopwatch.StartNew Dim k = ImageFinder.Contains(bm2, bm3) stp.Stop() res.Add(stp.ElapsedMilliseconds) Next ListBox1.Items.Add(String.Format("KMP: Image = {3}x{4}, Min = {0}, Max = {1}, Avg = {2}", res.Min, res.Max, res.Average, bm2.Width, bm2.Height)) res.Clear() For i = 1 To 10 Dim stp = Stopwatch.StartNew Dim k = bm2.ContainsSO(bm3) stp.Stop() res.Add(stp.ElapsedMilliseconds) Next ListBox1.Items.Add(String.Format("SO: Image = {3}x{4}, Min = {0}, Max = {1}, Avg = {2}", res.Min, res.Max, res.Average, bm2.Width, bm2.Height)) End If End Sub </code></pre> <p>I tested with large (8MP) and small (1MP) photos (no drawings, icons, etc) and found the kmp version roughly 2 times faster than the other approach. In absoulute numbers 40ms vs 75ms for an 8MP image tested on i7-2600. The result might depend on the types of images, because KMP (and others) win, when they can skip larger areas.</p>
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    1. POSearching a rectangle on the screen for and comparing to an image? Imagesearching
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    1. COIm going to try this out right now. I will report back. Thanks for taking the time to measure the speed.
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    2. COIm trying to figure out how to use a string(image path) for the second parameter of the contains function but can't figure it out.
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    3. CODo I have to open it to the memory from the path first then input the name into the second paramter?
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