问题
I am wondering how I could search a set rectangle on the screen and have it compare to an image that I specify to see if it matches?
Lets say it could Search x1 y1 to x2 y2 and compare against an image? and return the boolean?
I know Auto-it has a similar function seen here: http://www.autohotkey.com/docs/commands/ImageSearch.htm
Has anyone done this that they could reference? I am using vb.net.
EDIT: Abdias, I have put your code into a class instead and I am calling it like this:
Dim bm As Bitmap = Bitmap.FromFile(Label1.Text)
Dim bm2 As Bitmap = Bitmap.FromFile(Label2.Text)
Dim pnt As Point = ImageFinder.Contains(bm, bm2)
If pnt <> Nothing Then
MessageBox.Show("Possible match found at " & pnt.X.ToString() & " " & pnt.Y.ToString())
Else
MessageBox.Show("No match.")
End If
It seems that every set of images I try return no point. Even though they 100% contain eachother. I took an image and cropped it by a couple px and still did not return a match. I have made sure the source is larger. I tried saving a couple images as 24 bit jpg in paint and still nothing.
Here are two sample images.
回答1:
I made this function which can see if an image exist within a bigger image. It is written as an extension, but can easily be modified to a normal function as well as supporting a region.
To use it:
- Load main image into standard
Bitmapasbmp - Load image to look for into
bmpSearch
Then call:
Dim pt as Point = bmp.Contains(bmpSearch)
If pt <> Nothing Then
'... image found at pt
End If
The code for the extension (room for optimizations, but written as a 20 minute exercise for another question on this site):
'
'-- Extension for Bitmap
'
<Extension()>
Public Function Contains(src As Bitmap, ByRef bmp As Bitmap) As Point
'
'-- Some logic pre-checks
'
If src Is Nothing OrElse bmp Is Nothing Then Return Nothing
If src.Width = bmp.Width AndAlso src.Height = bmp.Height Then
If src.GetPixel(0, 0) = bmp.GetPixel(0, 0) Then
Return New Point(0, 0)
Else
Return Nothing
End If
ElseIf src.Width < bmp.Width OrElse src.Height < bmp.Height Then
Return Nothing
End If
'
'-- Prepare optimizations
'
Dim sr As New Rectangle(0, 0, src.Width, src.Height)
Dim br As New Rectangle(0, 0, bmp.Width, bmp.Height)
Dim srcLock As BitmapData = src.LockBits(sr, Imaging.ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb)
Dim bmpLock As BitmapData = bmp.LockBits(br, Imaging.ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb)
Dim sStride As Integer = srcLock.Stride
Dim bStride As Integer = bmpLock.Stride
Dim srcSz As Integer = sStride * src.Height
Dim bmpSz As Integer = bStride * bmp.Height
Dim srcBuff(srcSz) As Byte
Dim bmpBuff(bmpSz) As Byte
Marshal.Copy(srcLock.Scan0, srcBuff, 0, srcSz)
Marshal.Copy(bmpLock.Scan0, bmpBuff, 0, bmpSz)
' we don't need to lock the image anymore as we have a local copy
bmp.UnlockBits(bmpLock)
src.UnlockBits(srcLock)
Dim x, y, x2, y2, sx, sy, bx, by, sw, sh, bw, bh As Integer
Dim r, g, b As Byte
Dim p As Point = Nothing
bw = bmp.Width
bh = bmp.Height
sw = src.Width - bw ' limit scan to only what we need. the extra corner
sh = src.Height - bh ' point we need is taken care of in the loop itself.
bx = 0 : by = 0
'
'-- Scan source for bitmap
'
For y = 0 To sh
sy = y * sStride
For x = 0 To sw
sx = sy + x * 3
'
'-- Find start point/pixel
'
r = srcBuff(sx + 2)
g = srcBuff(sx + 1)
b = srcBuff(sx)
If r = bmpBuff(2) AndAlso g = bmpBuff(1) AndAlso b = bmpBuff(0) Then
p = New Point(x, y)
'
'-- We have a pixel match, check the region
'
For y2 = 0 To bh - 1
by = y2 * bStride
For x2 = 0 To bw - 1
bx = by + x2 * 3
sy = (y + y2) * sStride
sx = sy + (x + x2) * 3
r = srcBuff(sx + 2)
g = srcBuff(sx + 1)
b = srcBuff(sx)
If Not (r = bmpBuff(bx + 2) AndAlso
g = bmpBuff(bx + 1) AndAlso
b = bmpBuff(bx)) Then
'
'-- Not matching, continue checking
'
p = Nothing
sy = y * sStride
Exit For
End If
Next
If p = Nothing Then Exit For
Next
End If 'end of region check
If p <> Nothing Then Exit For
Next
If p <> Nothing Then Exit For
Next
bmpBuff = Nothing
srcBuff = Nothing
Return p
End Function
回答2:
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:
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 <> Imaging.PixelFormat.Format32bppArgb OrElse Child.PixelFormat <> Imaging.PixelFormat.Format32bppArgb Then Throw New ArgumentException("Narf again!")
If Parent.Width = Child.Width AndAlso Parent.Height = Child.Height AndAlso Parent.GetPixel(0, 0) <> Child.GetPixel(0, 0) Then Return Nothing
If Child.Width > Parent.Width OrElse Child.Height > 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 <= 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 > -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)) <> 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 < 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) > -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 < count - 1
If arr(start + pos - 1) = arr(start + cnd) Then
cnd += 1
table(pos) = cnd
pos += 1
ElseIf cnd > 0 Then
cnd = table(cnd)
Else
table(pos) = 0
pos += 1
End If
End While
Return table
End Function
End Class
I used the following "benchmark" function to compare against the code from Abdias Software :
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
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.
来源：https://stackoverflow.com/questions/13872079/searching-a-rectangle-on-the-screen-for-and-comparing-to-an-image-imagesearchin