vb Image grid detection - vb.net

Question

Im looking for a way to detect the center of grid squares when VB.net is feed an image
I want to start with an image of a grid with blue squares like this:
Grid
and i want the program to make an array of points in the center of each square like this (points aren't centered in picture)
Grid with Red points
i dont want to modify the image, i just want to get the points. I've tried getpixel for x and y but that just returns the same point
Dim search_color As Color = Color.FromArgb(255, 64, 128, 192)
Dim background_color As Color = Color.FromArgb(255, 240, 240, 240)
Dim grid_color As Color = Color.FromArgb(255, 144, 144, 144)
Dim pix As Color
Dim liney = 0, linex = 0
Dim loc, sloc, gloc As Point
For ch As Integer = 1 To 64
For y As Integer = liney To Bmp.Height - 1
For x As Integer = linex To Bmp.Width - 1
If Bmp.GetPixel(x, y) = search_color Then
sloc = New Point(x, y)
linex = x
liney = y
x = Bmp.Width - 1
y = Bmp.Height - 1
End If
Next
Next
Dim xloc = 0
For x As Integer = sloc.X To Bmp.Width - 1
If Bmp.GetPixel(x, sloc.Y) = grid_color Then
xloc = x - 1
End If
If Bmp.GetPixel(x, sloc.Y) = background_color Then
xloc = x - 1
End If
Next
For y As Integer = sloc.Y To Bmp.Height - 1
If Bmp.GetPixel(xloc, y) = grid_color Or Bmp.GetPixel(xloc, y) = background_color Then
gloc = New Point(xloc, y - 1)
End If
Next
loc = New Point((gloc.X + sloc.X) / 2, (gloc.Y + sloc.Y) / 2)
liney = gloc.Y
linex = gloc.X + 20
ListBox1.Items.Add(loc.ToString)
Next

Answer 1

Try this:
I added the following controls to a form to test the code:
pbImageToScan (PictureBox) - btnAnalyzeIMG (Button) - lbResult (ListBox)
Public Class Form1
Dim arrCenters() As Point
Dim bmpToAnalyze As Bitmap
Dim search_color As Color = Color.FromArgb(255, 64, 128, 192)
Dim background_color As Color = Color.FromArgb(255, 240, 240, 240)
Dim grid_color As Color = Color.FromArgb(255, 144, 144, 144)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
bmpToAnalyze = New Bitmap(Application.StartupPath & "\Image.bmp")
pbImageToScan.Image = Image.FromFile(Application.StartupPath & "\Image.bmp")
End Sub
Private Sub btnAnalyzeIMG_Click(sender As Object, e As EventArgs) Handles btnAnalyzeIMG.Click
FindCenters()
End Sub
Private Sub FindCenters()
bmpToAnalyze = New Bitmap(Application.StartupPath & "\Image.bmp")
pbImageToScan.Image = Image.FromFile(Application.StartupPath & "\Image.bmp")
'arrCenters is the array who will contains all centers data
ReDim arrCenters(0)
'arrCenters already starts with an element; this boolean is used to handle the first point insertion
Dim bFirstElementAddedToArray As Boolean
lbResult.Items.Clear()
Dim iIMGWidth As Integer = bmpToAnalyze.Width
Dim iIMGHeight As Integer = bmpToAnalyze.Height
'X, Y coordinates used for iterations
Dim iX As Integer = 0
Dim iY As Integer = 0
'Bitmap limits reached
Dim bExit As Boolean
'Used to skip a great part of Ys, if a match has been found along the current examinated line
Dim iDeltaYMax As Integer = 0
'Main cycle
Do While Not bExit
Dim colCurrentColor As Color = bmpToAnalyze.GetPixel(iX, iY)
If colCurrentColor = search_color Then
Dim iXStart As Integer = iX
Dim iYStart As Integer = iY
Dim iXEnd As Integer
Dim iYEnd As Integer
'Width of the Blue square
For iXEnd = iX + 1 To iIMGWidth - 1
Dim colColorSearchX As Color = bmpToAnalyze.GetPixel(iXEnd, iY)
If (colColorSearchX = background_color) Or (colColorSearchX = grid_color) Then
iXEnd -= 1
Exit For
End If
Next
'Height of the Blue square
For iYEnd = iY + 1 To iIMGHeight - 1
Dim colColorSearchY As Color = bmpToAnalyze.GetPixel(iXEnd, iYEnd)
If (colColorSearchY = background_color) Or (colColorSearchY = grid_color) Then
iYEnd -= 1
Exit For
End If
Next
iDeltaYMax = iYEnd - iYStart
'Blue square center coordinates
Dim pCenter As New Point((iXStart + iXEnd) / 2, (iYStart + iYEnd) / 2)
Dim iArrLenght As Integer = 0
If Not bFirstElementAddedToArray Then
bFirstElementAddedToArray = True
Else
iArrLenght = arrCenters.GetLength(0)
ReDim Preserve arrCenters(iArrLenght)
End If
arrCenters(iArrLenght) = pCenter
lbResult.Items.Add(pCenter.ToString)
iX = iXEnd
'Checks if the Width limit of the bitmap has been reached
If iX = (iIMGWidth - 1) Then
iX = 0
iY += iDeltaYMax + 1
iDeltaYMax = 0
Else
iX += 1
End If
Else
'Checks if the Width limit of the bitmap has been reached
If iX = (iIMGWidth - 1) Then
iX = 0
iY += iDeltaYMax + 1
iDeltaYMax = 0
Else
iX += 1
End If
End If
'Width and Height limit of the bitmap have been reached
If (iX = iIMGWidth - 1) And (iY = iIMGHeight - 1) Then
bExit = True
End If
Loop
'Draws a Red point on every center found
For Each P As Point In arrCenters
bmpToAnalyze.SetPixel(P.X, P.Y, Color.Red)
Next
pbImageToScan.Image = bmpToAnalyze
End Sub
End Class