asked on

Picture Binarization problem

Hi,
I would like to load a picture and convert into binary image
I can load the picture and convert but cannot save. what 's wrong?

''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Private Sub cmdLoad_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdLoad.Click

Dim hDC As Integer
            CommonDialog1.Filter = "(*.bmp;*.ico;*.gif;*.jpg)|*.bmp;*.ico;*.gif;*.jpg"
            CommonDialog1.ShowOpen()

            sFile = CommonDialog1.FileName

            If sFile <> "" Then
                  Picture1.Image = System.Drawing.Image.FromFile(sFile)
'hDCSour = CreateCompatibleDC(Picture1.Handle)
hDCSour = CreateCompatibleDC(hDC)

hBMPSour = CreateCompatibleBitmap(hDC, Picture1.ClientRectangle.Width, Picture1.ClientRectangle.Height)
hDCDest = CreateCompatibleDC(hDC)
hBMPDest = CreateCompatibleBitmap(hDC, Picture1.ClientRectangle.Width, Picture1.ClientRectangle.Height)

                  SelectObject(hDCSour, hBMPSour)
                  SelectObject(hDCDest, hBMPDest)

' BitBlt(hDCSour, 0, 0, Picture1.ClientRectangle.Width, Picture1.ClientRectangle.Height, hDC, 0, 0, vbSrcCopy)
BitBlt(hDCDest, 0, 0, Picture1.ClientRectangle.Width, Picture1.ClientRectangle.Height, hDCSour, 0, 0, SRCCOPY)

            End If
      End Sub

      Private Sub cmdSave_Click(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles cmdSave.Click
            'stores the counter value
            Static a As Integer
            a = a + 1
            Picture1.Image.Save(VB6.GetPath & "\pict" & a & ".bmp")
      End Sub


      Sub Grayscaling(ByRef pfIndex As Short)
Dim pX, pY, hDC As Integer
            Dim x, y As Integer
            Dim colorval As Integer
            Dim green, red, blue As Integer
            Dim green2, red2, blue2 As Integer

            pX = Picture1.ClientRectangle.Width - 1
            pY = Picture1.ClientRectangle.Height - 1

            'loop through each pixel
            For x = 0 To pX
                  For y = 0 To pY
                        colorval = GetPixel(hDCSour, x, y)

If colorval >= 128 Then red2 = 255
If colorval < 128 Then red2 = 0
green2 = red2
blue2 = red2

SetPixel(hDCDest, x, y, RGB(red2, green2, blue2))
Next y
            Next x
BitBlt(hDCDes, 0, 0, Picture1.ClientRectangle.Width, Picture1.ClientRectangle.Height, hDCSour, 0, 0, SRCCOPY)
            Picture1.Refresh()

      End Sub

      Private Sub Form1_Closed(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Closed
            DeleteObject(hBMPSour)
            DeleteDC(hDCSour)
            DeleteObject(hBMPDest)
            DeleteDC(hDCDest)
      End Sub

LordWabbit

Whats the error message returned?
Try changing
Picture1.Image.Save(VB6.GetPath & "\pict" & a & ".bmp")
to
Picture1.Image.Save(Application.StartupPath & "\pict" & a & ".bmp")

Also try placing a breakpoint to check that the path and filename are valid

gorexy

ASKER

no errors just it cannot produce the BMP file

LordWabbit

Mmmmm, the code in the cmdSave

'stores the counter value
Static a As Integer
a = a + 1
Picture1.Image.Save(VB6.GetPath & "\pict" & a & ".bmp")

a will always be 1, are you not simply overwriting the file (IS there a pict1.bmp file in the destination path?)

LordWabbit

Ooops my bad it was declared static (didn't see that)

Mike Tomlinson

This definitely looks like VB6 code ported over to VB.Net.

I haven't analyzed the code in depth...but I'm pretty sure you can achieve what you need using ALL native .Net code:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
OpenFileDialog1.Filter = "(*.bmp;*.ico;*.gif;*.jpg)|*.bmp;*.ico;*.gif;*.jpg"
If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
Dim fileName As String = OpenFileDialog1.FileName
Dim bmp As Bitmap = Bitmap.FromFile(fileName)
Dim bmp2 As New Bitmap(bmp)
Dim c As Color
For x As Integer = 0 To bmp.Width - 1
For y As Integer = 0 To bmp.Height - 1
c = bmp.GetPixel(x, y)
' analyze the color somehow...
If c.R < 125 And c.B < 125 Then
' set a pixel in your new bitmap...
bmp2.SetPixel(x, y, Color.FromArgb(someRedValue, someGreenValue, someBlueValue))
End If
Next
Next
bmp.Dispose()
PictureBox1.Image = bmp2
bmp2.Save("yourNewFileNameHere.bmp")
End If
End Sub

Bob Learned

Here is a working example of converting an image to grayscale:

http://www.bobpowell.net/grayscale.htm

Bob

gorexy

ASKER

Hi Ide_mind
your code is great and simple, just a few questions:

1. what is C.B, C.R?
If i want to turn my pic into Black and White only, how to set?
2. it can output the bmp file but invalid (cannot be opened)

Thanks

Mike Tomlinson

C.R, C.B and C.G will give you the value of the red, green and blue components of that color.

You can specify the image format when you save the file. Something like...

bmp2.Save(fileName, System.Drawing.Imaging.ImageFormat.Bmp)

Did you try the code in Bob's link?

Here is the formula in that link applied to my code. It saves a greyscale image using the same filename but with a .bmp extension. If the file was already a bmp then it is REPLACED with the greyscale version:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim OpenFileDialog1 As New OpenFileDialog
OpenFileDialog1.Filter = "(*.bmp;*.ico;*.gif;*.jpg)|*.bmp;*.ico;*.gif;*.jpg"
If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
Dim fileName As String = OpenFileDialog1.FileName
Dim bmp As Bitmap = Bitmap.FromFile(fileName)
Dim bmp2 As New Bitmap(bmp)
bmp.Dispose()

Dim c As Color
Dim luma As Integer
For x As Integer = 0 To bmp2.Width - 1
For y As Integer = 0 To bmp2.Height - 1
c = bmp2.GetPixel(x, y)
luma = CInt(c.R * 0.3 + c.G * 0.59 + c.B * 0.11)
bmp2.SetPixel(x, y, Color.FromArgb(luma, luma, luma))
Next
Next

Dim fi As New System.IO.FileInfo(fileName)
If fi.Extension.ToUpper <> ".BMP" Then
fileName = fi.FullName.Substring(0, fi.Name.LastIndexOf(fi.Extension)) & ".bmp"
End If
bmp2.Save(fileName, System.Drawing.Imaging.ImageFormat.Bmp)
End If
End Sub

gorexy

ASKER

finally i use the code to display B/W pic

For x As Integer = 0 To bmp.Width - 1
For y As Integer = 0 To bmp.Height - 1
c = bmp.GetPixel(x, y)
' analyze the color somehow...
If c.R < 125 Then
' set a pixel in your new bitmap...
bmp2.SetPixel(x, y, Color.FromArgb(0, 0, 0))
End If

If c.B >= 125 Then
bmp2.SetPixel(x, y, Color.FromArgb(255, 255, 255))
End If

Next
Next

Can I further operate the thresholed pic?

ASKER CERTIFIED SOLUTION

Mike Tomlinson

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

gorexy

ASKER

yes the code works now.

as I am trying to play with barcode like reading and so I try to threhold the image into black/white and then decode them into 0101010...

do you think it works?