Android Question opencv detect circle

mohmmad mustaf

New Member
Hello, I am looking for someone to help me
I designed an application to read the exam paper for the student, which consists of multiple-choice questions, so that the student shades the symbol for the correct answer in the form of a circle, as in Picture No. (1). When applying the attached code, several problems appear.
1- It does not read all the shaded circles. What are the best variables to make it read all?
2- When drawing the circles that were selected from the application, they do not appear on the screen, but rather appear as if they were drawn on a thumbnail as in the second image (see the white dots in the left corner from the top)
Please Help

#Region  Project Attributes
    #ApplicationLabel: Ellipse Detection
    #VersionCode: 1
    'SupportedOrientations possible values: unspecified, landscape or portrait.
    #SupportedOrientations: portrait
    #CanInstallToExternalStorage: False
#End Region

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.
    Dim ocl As OCVOpenCVLoader
    Dim const MaxImageCount = 1
    Dim srcIV(MaxImageCount),dstIV As ImageView
    Dim srcBitmap(MaxImageCount),dstBitmap As Bitmap
    Dim srcMat,tmpMat,dstMat As OCVMat
    Dim selectedIndex As Int=0        'by default, select first picture
    Dim mCore As OCVCore
    Dim mUtils As OCVUtils
    Dim mImgProc As OCVImgproc
    Dim mCvType As OCVCvType

End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:

    'Prepare layout  
    'Load our test pics
    Dim k As Int
    For k=0 To MaxImageCount -1
        srcBitmap(k).Initialize(File.DirAssets,"test0.jpg")                'Image source:
    Activity.AddView(dstIV, 0,100dip,300dip, 500dip )    'keep aspect ratio.

End Sub

Sub srcIV_Click
    Dim IV As ImageView=Sender
    Dim index As Int = IV.Tag
    If index>=0 And index<=1 Then
        selectedIndex = index
    '    CallSubDelayed(Me,"ProcessImage")
    End If
End Sub

Sub processcircle()
    Dim edge As OCVMat
    Dim circles As OCVMat
    dstBitmap.InitializeMutable(tmpMat.size.width, tmpMat.size.height)
    mImgProc.cvtColor1(tmpMat, tmpMat, mImgProc.COLOR_RGBA2GRAY)

    mImgProc.medianBlur(tmpMat, edge, 5)
    ' Detect circles
    mImgProc.HoughCircles(edge, circles, mImgProc.HOUGH_GRADIENT, 1, edge.rows / 16, 80, 30, 0, 30)
    Log(circles.rows & " " & circles.cols & " " & circles.depth)

    Dim myColorScalar As OCVScalar
    myColorScalar.Initialize3(255, 0, 0)

    For i = 0 To circles.cols - 1
            Dim circleData() As Double
            circleData = circles.get5(0, i)

            ' Extract circle information
            Dim centerX As Double = circleData(0)
            Dim centerY As Double = circleData(1)
            Dim radius As Double = circleData(2)

            ' Adjust the center coordinates if needed based on the coordinate system
            Dim adjustedCenterX As Double = centerX
            Dim adjustedCenterY As Double =centerY' tmpMat.size.height - centerY  ' Invert Y-axis if necessary

            Dim P1 As OCVPoint
            P1.Initialize(adjustedCenterX, adjustedCenterY)
  , P1, radius, myColorScalar, -1, 1, 2)

            Log("Circle " & i & ": CenterX=" & adjustedCenterX & ", CenterY=" & adjustedCenterY & ", Radius=" & radius)

        End Try

    mUtils.matToBitmap1(srcMat, dstBitmap)
    dstIV.Bitmap = dstBitmap
End Sub

Sub Activity_Resume
End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub


  • test0.jpg
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