Question

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.

Answer 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 Bitmap as bmp
• 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