Android Question Detecting color using Opencv

warayTek

Member
Licensed User
Hello everyone, can anyone point me in the direction of how to identify if a certain color exists for example red by returning true or false? This is the code I'm trying to modify.
B4X:
#Region  Project Attributes
    #ApplicationLabel: OCV Image Manipulations
    #VersionCode: 2
    #VersionName:
    '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.
    Dim NUM_IMAGES As Int =1
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 names(NUM_IMAGES) As String = Array As String("test1.jpg")
    Dim srcIV(NUM_IMAGES),dstIV As ImageView
    Dim srcBitmap(NUM_IMAGES),dstBitmap As Bitmap
 
 
    Dim srcMat,tmpMat,tmpMatGray,dstMat As OCVMat
 
    Dim selectedIndex As Int=0        'by default, select first picture

    Dim optionCaption(10) As String = Array As String("HFlip","VFlip","color swap","Blur","Draw marker","Canny","dilate","erode","circles","Detect color red")
    Dim optionChecked(10) As Boolean = Array As Boolean(False,False,False,False,False,False,False,False,False,False)
 
    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:
    'Activity.LoadLayout("Layout1")

    '--------------------------------------
    'Prepare layout
    '--------------------------------------
 
    'Load our test pics
    Dim k As Int
    For k=0 To NUM_IMAGES-1
        srcBitmap(k).Initialize(File.DirAssets,names(k))'"test"&k&".jpg")                'Image source: https://wallpaperbrowse.com/media/images/Images-3.jpg
        srcIV(k).Initialize("srcIV")
        srcIV(k).Gravity=Gravity.FILL
        srcIV(k).Tag=k
        Activity.AddView(srcIV(k),k*(120dip),0,100dip,75dip)
        srcIV(k).Bitmap=srcBitmap(k)
    Next
 
    dstIV.Initialize("")
    dstIV.Gravity=Gravity.FILL
    Activity.AddView(dstIV, 2dip,100dip,100%X, 100%X*480/640 )    'keep aspect ratio.
    dstBitmap.InitializeMutable(640,480)
    dstIV.Bitmap = dstBitmap
 
    'Options
    Dim chkOptions(10) As CheckBox
    Dim k As Int
    For k=0 To chkOptions.Length-1
        Log(k)
        chkOptions(k).Initialize("chkOptions")
        chkOptions(k).Tag  = k
        chkOptions(k).Text = optionCaption(k)
        Activity.AddView( chkOptions(k), 20dip +  160dip*Floor(k/5) , 365dip + 30dip*(k Mod 5), 140dip, 30dip)
    Next

 
 
    mUtils.bitmapToMat1(srcBitmap(selectedIndex),srcMat)

End Sub


Sub srcIV_Click
    Dim IV As ImageView=Sender
    Dim index As Int = IV.Tag
    If index>=0 And index<NUM_IMAGES Then
        selectedIndex = index
        mUtils.bitmapToMat1(srcBitmap(selectedIndex),srcMat)
        CallSubDelayed(Me,"ProcessImage")
    End If
End Sub


Sub  chkOptions_CheckedChange(Checked As Boolean)
    Dim chk As CheckBox = Sender
    Dim index As Int = chk.tag
    If index>=0 And index<10 Then
        optionChecked(index) = chk.Checked
        CallSubDelayed(Me,"ProcessImage")
    End If
End Sub


Sub ProcessImage
 
    srcMat.copyTo( tmpMat)                                                        ' Clone source
 
    '============================================================================================
    ' Apply different operations based on selected options
    '============================================================================================
    If optionChecked(0)=True Then    mCore.flip(tmpMat, tmpMat, 1)                                    ' FLip horizontally

    If optionChecked(1)=True Then    mCore.flip(tmpMat, tmpMat, 0)                                    ' FLip vertically

    If optionChecked(2)=True Then     mImgProc.cvtColor1(tmpMat,tmpMat,mImgProc.COLOR_RGBA2BGRA)        ' Color swap

    If optionChecked(3)=True Then                                                                    ' Blur
        Dim mSize As OCVSize
        mSize.Initialize2(Array As Double(5,5))
        mImgProc.blur2(tmpMat,tmpMat,mSize)                                   
    End If
 
    If optionChecked(4)=True Then                                                                     ' Draw marker
        Dim myPos As OCVPoint
        myPos.Initialize( tmpMat.cols()/2, tmpMat.rows()/2)
        Dim myColorScalar As OCVScalar
        myColorScalar.Initialize3(0,255,0)   
        mImgProc.drawMarker1(tmpMat,myPos,myColorScalar)                   
    End If
 
    If optionChecked(5)=True Then                                                                    ' Canny
        mImgProc.cvtColor1(tmpMat,tmpMat,mImgProc.COLOR_RGBA2GRAY)
        mImgProc.Canny3(tmpMat,tmpMat,50,150)        'Change thresholds according to desired results. A good rule of thumb to start is that th2 = 3*th1
    End If
 
    If optionChecked(6)=True Then
        Dim mKernel As OCVMat
        mKernel.Initialize2(5,5, mCvType.CV_8UC1)
        mImgProc.dilate2(tmpMat,tmpMat,mKernel)                                                        ' Dilate
    End If
 
    If optionChecked(7)=True Then                                                                    ' Erode
        Dim mKernel As OCVMat
        mKernel.Initialize2(5,5, mCvType.CV_8UC1)
        mImgProc.erode2(tmpMat,tmpMat,mKernel)
    End If
    
    If optionChecked(8)=True Then
    
        ' If option8 is enabled, te other ones don't have any effect (these two lines get again the original image)
        srcMat.copyTo( tmpMat)
        mImgProc.cvtColor1(tmpMat,tmpMatGray,mImgProc.COLOR_RGBA2GRAY)
    
        'HoughCircles --> function reference: http://docs.opencv.org/2.4/modules/imgproc/doc/feature_detection.html?highlight=houghcircles#houghcircles
        Dim myColorScalar As OCVScalar
        myColorScalar.Initialize3(0,255,0)
        Dim circles As OCVMatOfPoint3f
        circles.Initialize
        'dp=1 --> scaling factor of the algorith. 1=start with the original image
        'minDistance --> to prevent false positives. But if circles are concentrical, leave this factor as small as possible
        'mImgProc.HoughCircles1(    tmpMatGray,circles,mImgProc.HOUGH_GRADIENT,1,10)
        mImgProc.HoughCircles(tmpMatGray,circles,mImgProc.HOUGH_GRADIENT,1.0d,10,150,100,20,240)
        'The function HoughCircles returns an array of 3-points (x,y,radius)
        Log(circles.rows&" "&circles.cols&" "&circles.depth)
        Dim allCircles() As OCVPoint3= circles.toArray()
        For k=0 To allCircles.Length-1

            Log("Detected circle: x="&allCircles(k).x &" y="& allCircles(k).y &" radius="& allCircles(k).z)

            'We draw a colored circle with those coordinates
            Dim xyPoint As OCVPoint
            xyPoint.Initialize(allCircles(k).x,allCircles(k).y)
            mImgProc.circle2(tmpMat,xyPoint,allCircles(k).z,myColorScalar)

        Next
 
 
    End If
 
    
    If optionChecked(9)=True Then                                                                    ' Erode
        Log("checkbox9")

    End If
    '============================================================================================
    ' Convert Mat to Bitmap
    '============================================================================================
 
    mUtils.matToBitmap1(tmpMat,dstBitmap)
    dstIV.invalidate

End Sub


Sub Activity_Resume
    ProcessImage
End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub


' Not added to the layout. But we can easily save any OCVMat after converting it to bitmap
#If 0
Sub btnSave_Click
    SaveBitmapToFile(dstBitmap,File.DirRootExternal,"processedbitmap.jpg")
End Sub

Sub SaveBitmapToFile(b As Bitmap, myDir As String, myFilename As String)
    
    Dim Out As OutputStream = File.OpenOutput(myDir, myFilename,False)
    b.WriteToStream(Out,100,"JPEG")
    Out.Flush
    Out.Close
 
End Sub
 #End If
What is the function that scans for an image from pixel 0,0?

any help is much appreciated, thanks.
 

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