30
Mar
09

[VB.Net] Q: Get the amount and colour of pixels in an Image

The question asked “How do i get the amount and colour of pixels in an Image?”

The Solution
I had to think a bit about this one, dealing with image processing needs to be as efficent as possible, however I couldnt see a better way than just looping through the pixels and adding them to a list.
Here is the solution that I posted to the users project:

    Dim PixelList As New List(Of String())

    Public Sub ColourInList(ByVal Colour As Color)
        Dim Found As Boolean = False
        For Each str As String() In PixelList
            If str(0) = CStr(Colour.ToArgb) Then
                str(1) = CStr(CInt(str(1)) + 1)
                Found = True
                Exit For
            End If
        Next
        If Found = False Then PixelList.Add(New String() {CStr(Colour.ToArgb), 1})
    End Sub

    Private Sub PictureBox1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PictureBox1.Click
        Dim btmp As New Bitmap(PictureBox1.Image)
        For x As Integer = 0 To btmp.Width - 1
            For y As Integer = 0 To btmp.Height - 1
                ColourInList(btmp.GetPixel(x, y))
            Next
        Next
        For Each str As String() In PixelList
            Debug.WriteLine(Color.FromArgb(str(0)).ToString & " | Count: " & str(1))
        Next
    End Sub

Would Output:
Using this Image:
http://privatewww.essex.ac.uk/~sjs/research/iso_colour_blocks.png

Color [A=255, R=85, G=85, B=85] | Count: 65536
Color [A=255, R=0, G=255, B=0] | Count: 32768
Color [A=255, R=127, G=0, B=128] | Count: 32768
Color [A=255, R=0, G=0, B=255] | Count: 32768
Color [A=255, R=127, G=128, B=0] | Count: 32768
Color [A=255, R=255, G=0, B=0] | Count: 32768
Color [A=255, R=0, G=127, B=128] | Count: 32768

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1 Response to “[VB.Net] Q: Get the amount and colour of pixels in an Image”



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