Notification When Screen is Flashing VB.Net - vb.net

Question

I would like a notification to be triggered when part the screen starts to flash. This notification can be a msgbox for now, but I will eventually evolve it into an audible sound.
The purpose of this is we have a dashboard that displays various cells throughout the company. When a cell needs assistance, its spot on the dashboard starts to flash. The cells are displayed in horizontally stackedboxes like this;
Cell 1
Cell 2
Cell 3
Ect...
I would like to build an application that scans the screen, lets say every second, and gets each cells pixel intensity.
The notification will be triggered if/when the cells pixel intensity changes each scan for three consecutive scans in a row (ie. the cell must be flashing).
I am hoping that you guys can help me find a way to scan the screen an return a regions average pixel intensity to which I can then replicate and do the comparison to find out if it is flashing.
Thank you in advance, I am using VB.Net.

Answer 1

I was able to accomplish what I was asking by using this:
Private Sub AvgColors(ByVal InBitmap As Bitmap)
Dim btPixels(InBitmap.Height * InBitmap.Width * 3 - 1) As Byte
Dim hPixels As GCHandle = GCHandle.Alloc(btPixels, GCHandleType.Pinned)
Dim bmp24Bpp As New Bitmap(InBitmap.Width, InBitmap.Height, InBitmap.Width * 3,
Imaging.PixelFormat.Format24bppRgb, hPixels.AddrOfPinnedObject)
Using gr As Graphics = Graphics.FromImage(bmp24Bpp)
gr.DrawImageUnscaledAndClipped(InBitmap, New Rectangle(0, 0,
bmp24Bpp.Width, bmp24Bpp.Height))
End Using
Dim sumRed As Int32
Dim sumGreen As Int32
Dim sumBlue As Int32
For i = 0 To btPixels.Length - 1 Step 3
sumRed += btPixels(i)
sumGreen += btPixels(i + 1)
sumBlue += btPixels(i + 2)
Next
hPixels.Free()
Dim avgRed As Byte = CByte(sumRed / (btPixels.Length / 3))
Dim avgGreen As Byte = CByte(sumGreen / (btPixels.Length / 3))
Dim avgBlue As Byte = CByte(sumBlue / (btPixels.Length / 3))
MsgBox(avgRed & vbCrLf & avgGreen & vbCrLf & avgBlue)
End Sub
Private Function Screenshot() As Bitmap
Dim b As Bitmap = New Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height)
Using g As Graphics = Graphics.FromImage(b)
g.CopyFromScreen(0, 0, 0, 0, b.Size, CopyPixelOperation.SourceCopy)
g.Save()
End Using
Return b
End Function
and from here I can just adjust the range of bitmap to what I need, add a timer to tick every second, and keep a variable to compare average RGB's to.
Most of the code found from here:
http://www.vbforums.com/showthread.php?776021-RESOLVED-Getting-Average-RGB-Color-Value-of-Entire-Screen