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October 8th, 2008, 10:59 PM
#1
Black and white picture
hi
i have written program to trun a picture in black and white
but problem with this code is that it is very slow specialy for high resolution picture
i have a written a function which gives black and white
i m running a loop through image height and width and setting each pixel and also getting each pixel
i think that is problem why it is slow
when i run my program , i have to wait for minutes and quality of image is not so good also
code for black and white function
Code:
Public Function PureBW(ByVal image As System.Drawing.Bitmap, Optional ByVal Mode As BWMode = BWMode.By_Lightness, Optional ByVal tolerance As Single = 0) As System.Drawing.Bitmap
image = Me.PictureBox1.Image
Dim x As Integer
Dim y As Integer
If tolerance > 1 Or tolerance < -1 Then
Throw New ArgumentOutOfRangeException
Exit Function
End If
For x = 0 To image.Width - 1 Step 1
For y = 0 To image.Height - 1 Step 1
Dim clr As Color = image.GetPixel(x, y)
If Mode = BWMode.By_RGB_Value Then
If (CInt(clr.R) + CInt(clr.G) + CInt(clr.B)) > 383 - (tolerance * 383) Then
image.SetPixel(x, y, Color.White)
Else
image.SetPixel(x, y, Color.Black)
End If
Else
If clr.GetBrightness > 0.5 - (tolerance / 2) Then
image.SetPixel(x, y, Color.White)
Else
image.SetPixel(x, y, Color.Black)
End If
End If
Next
Next
Return image
End Function
i want it to change, i want that it should work quickly
what changes this need and any alternative method available to do that??
i have an other function for inverting the picture
it is very fast, here i m using a matrix
Code:
Public Function InvertImage(ByVal img As Image) As Boolean
Dim cm As ColorMatrix = New ColorMatrix(New Single()() _
{New Single() {-1, 0, 0, 0, 0}, _
New Single() {0, -1, 0, 0, 0}, _
New Single() {0, 0, -1, 0, 0}, _
New Single() {0, 0, 0, 1, 0}, _
New Single() {1, 1, 1, 1, 1}})
Return DrawImage(img, cm)
End Function
can i get black and white image from above function,if yes then how??
what changes i need in above function to get desire result?
thanks
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October 9th, 2008, 08:15 AM
#2
Re: Black and white picture
 Originally Posted by aamir55
...
Code:
Public Function PureBW(ByVal image As System.Drawing.Bitmap, Optional ByVal Mode As BWMode = BWMode.By_Lightness, Optional ByVal tolerance As Single = 0) As System.Drawing.Bitmap
image = Me.PictureBox1.Image
Dim x As Integer
Dim y As Integer
If tolerance > 1 Or tolerance < -1 Then
Throw New ArgumentOutOfRangeException
Exit Function
End If
For x = 0 To image.Width - 1 Step 1 'Step 1 is probably unnecesary
For y = 0 To image.Height - 1 Step 1
Dim clr As Color = image.GetPixel(x, y)
If Mode = BWMode.By_RGB_Value Then
If (CInt(clr.R) + CInt(clr.G) + CInt(clr.B)) > 383 - (tolerance * 383) Then
image.SetPixel(x, y, Color.White)
Else
image.SetPixel(x, y, Color.Black)
End If
Else
If clr.GetBrightness > 0.5 - (tolerance / 2) Then
image.SetPixel(x, y, Color.White)
Else
image.SetPixel(x, y, Color.Black)
End If
End If
Next
Next
Return image
End Function
This should be a bit faster:
Code:
Public Function PureBW(ByVal image As System.Drawing.Bitmap, _
Optional ByVal Mode As BWMode = BWMode.By_Lightness, _
Optional ByVal tolerance As Single = 0) As System.Drawing.Bitmap
image = Me.PictureBox1.Image
Dim x As Integer
Dim y As Integer
If tolerance > 1 Or tolerance < -1 Then
Throw New ArgumentOutOfRangeException
Exit Function
End If
Dim clr As Color
Dim ColorLimit As Integer
Dim White As Color = Color.White
Dim Black As Color = Color.Black
If Mode = BWMode.By_RGB_Value Then
ColorLimit = CInt(383 - (tolerance * 383))
With image
For x = 0 To .Width - 1 'Step 1
For y = 0 To .Height - 1 'Step 1
clr = .GetPixel(x, y)
If (CInt(clr.R) + CInt(clr.G) + CInt(clr.B)) > ColorLimit Then
.SetPixel(x, y, White)
Else
.SetPixel(x, y, Black)
End If
Next y
Next x
End With 'image
Else
ColorLimit = CInt(0.5 - (tolerance / 2))
With image
For x = 0 To .Width - 1 ' Step 1
For y = 0 To .Height - 1 'Step 1
clr = .GetPixel(x, y)
If clr.GetBrightness > ColorLimit Then
.SetPixel(x, y, White)
Else
.SetPixel(x, y, Black)
End If
Next y
Next x
End With 'image
End If
Return image
End Function
Surely all the time is taken by the image.SetPixel, .GetPixel, and clr.GetBrightness function calling.
If you find a fast mode to store those values in a matrix, you can calculate faster.
i want it to change, i want that it should work quickly
what changes this need and any alternative method available to do that??
i have an other function for inverting the picture
it is very fast, here i m using a matrix
Code:
Public Function InvertImage(ByVal img As Image) As Boolean
Dim cm As ColorMatrix = New ColorMatrix(New Single()() _
{New Single() {-1, 0, 0, 0, 0}, _
New Single() {0, -1, 0, 0, 0}, _
New Single() {0, 0, -1, 0, 0}, _
New Single() {0, 0, 0, 1, 0}, _
New Single() {1, 1, 1, 1, 1}})
Return DrawImage(img, cm)
End Function
can i get black and white image from above function,if yes then how??
what changes i need in above function to get desire result?
thanks
I have not an idea why that could work (it should not work at all).
[Vb.NET 2008 (ex Express)]
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