[2005] color --> black & white

[Wytse Talsma]

How do you convert an image in an imagebox that is in color, to black and white and/or get the edges inside the image with Visual Studio 2005?

[drpcken]

A very simple solution would be to have two copies of the image, one in color, and one in grayscale. Then use whatever event (ie button click) to 'convert' the image, but just replace it with the black and white one.

PictureBox1.Image = "GrayScaleImage.bmp"

[Wytse Talsma]

yeah but how can I convert it?

[dim_kevin_as_human]

there might be an easier way...but...in express 2005


acquire the image and pass it to your function

grayscale1(image)

edit the numbers (ie .299 .114) to achieve desired effect.

Public Function grayscale1(ByVal img As Image, ByVal Instance As Integer) As Boolean
 
        Dim cm As Imaging.ColorMatrix = New Imaging.ColorMatrix(New Single()() _
                           {New Single() {0.299, 0.299, 0.299, 0, 0}, _
                            New Single() {500, 500, 500, 0, 0}, _
                            New Single() {0.114, 0.114, 0.114, 0, 0}, _
                            New Single() {0, 0, 0, 1, 0}, _
                            New Single() {0, 0, 0, 0, 1}})
 
 
        Return draw_adjusted_image(img, cm, Instance)

draw and save it...

rivate Function draw_adjusted_image(ByVal img As Image, ByVal cm As Imaging.ColorMatrix, _
                                            ByVal instance As Integer) As Boolean
 
        Try
            Dim bmp As New Bitmap(img) ' create a copy of the source image 
            Dim imgattr As New Imaging.ImageAttributes()
            Dim rc As New Rectangle(0, 0, img.Width, img.Height)
            Dim g As Graphics = Graphics.FromImage(img)
 
            ' associate the ColorMatrix object with an ImageAttributes object
            imgattr.SetColorMatrix(cm)
 
            ' draw the copy of the source image back over the original image, 
            'applying the ColorMatrix
            g.DrawImage(bmp, rc, 0, 0, img.Width, img.Height, _
                                   GraphicsUnit.Pixel, imgattr)
 
            Dim strPath As String = Application.StartupPath ' & "\image"
            img.Save("image.jpg")
 
 
            g.Dispose()
 
            Return True
 
        Catch
            'code....
        End Try
 
    End Function

and then you can code the load into your picture box.

[gigemboy]

Check out this thread where it had been discussed before...

http://www.vbforums.com/showthread.php?t=376900

[Wytse Talsma]

I came out on this, but it isn't working :|
I call the bw() inside the main load.

Public Function grayscale1(ByVal img As Drawing.Image, ByVal Instance As Integer) As Boolean
 
        Dim cm As Drawing.Imaging.ColorMatrix = New Drawing.Imaging.ColorMatrix(New Single()() _
                           {New Single() {0.299, 0.299, 0.299, 0, 0}, _
                            New Single() {500, 500, 500, 0, 0}, _
                            New Single() {0.114, 0.114, 0.114, 0, 0}, _
                            New Single() {0, 0, 0, 1, 0}, _
                            New Single() {0, 0, 0, 0, 1}})
 
 
        Return draw_adjusted_image(img, cm, Instance)
 
    End Function
    Private Function draw_adjusted_image(ByVal img As Drawing.Image, ByVal cm As Drawing.Imaging.ColorMatrix, _
                                            ByVal instance As Integer) As Boolean
 
        Try
            Dim bmp As New Drawing.Bitmap(img) ' create a copy of the source image 
            Dim imgattr As New Drawing.Imaging.ImageAttributes()
            Dim rc As New Drawing.Rectangle(0, 0, img.Width, img.Height)
            Dim g As Drawing.Graphics = Drawing.Graphics.FromImage(img)
 
            ' associate the ColorMatrix object with an ImageAttributes object
            imgattr.SetColorMatrix(cm)
 
            ' draw the copy of the source image back over the original image, 
            'applying the ColorMatrix
            g.DrawImage(bmp, rc, 0, 0, img.Width, img.Height, _
                                   Drawing.GraphicsUnit.Pixel, imgattr)
 
            Dim strPath As String = Application.StartupPath ' & "\image"
            img.Save("\image.bmp")
 
 
            g.Dispose()
 
            Return True
 
        Catch
            'code....
        End Try
        codebox2.ImageLocation = "\image.bmp"
    End Function
 
    Public Function bw()
        Dim image As Drawing.Bitmap
        image = PictureBox1.Image
        grayscale1(image, True)
    End Function

[Wytse Talsma]

Never mind got it already
just forgotten something

[Wytse Talsma]

Hmmm, ive another prob.
if the background of the image is white, then there's an whole white new grey-scale image created. and if the background is black, then he just does fine.
So I want to make an check if the background is white or black at some x/y coordinates. how to get a pixel at postion x, y ?
and this code converts color into white and leaves black as it is:

Dim cm As Drawing.Imaging.ColorMatrix = New Drawing.Imaging.ColorMatrix(New Single()() _
                               {New Single() {0.299, 0.299, 0.299, 0, 0}, _
                                New Single() {500, 500, 500, 0, 0}, _
                                New Single() {0.114, 0.114, 0.114, 0, 0}, _
                                New Single() {0, 0, 0, 1, 0}, _
                                New Single() {0, 0, 0, 0, 1}})

but how to leave white as it is and converts color into black?

[dim_kevin_as_human]

try

Dim cm As Imaging.ColorMatrix = New Imaging.ColorMatrix(New Single()() _
                           {New Single() {0.299, 0.299, 0.299, 0, 0}, _
                            New Single() {0.599, 0.599, 0.599, 0, 0}, _
                            New Single() {0.114, 0.114, 0.114, 0, 0}, _
                            New Single() {0, 0, 0, 1, 0}, _
                            New Single() {0, 0, 0, 0, 1}})

if that doesn't work for you, try adjusting the numbers