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| Title | Remap a color in an image in VB .NET |
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| Description | This example shows how to remap a color in an image in VB .NET. |
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| Keywords | image processing, remap color, color, VB .NET |
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| Categories | Graphics, VB.NET |
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When you clik the Go button, the program uses the values you entered in TextBoxes to makes two colors. It stores the colors in a ColorMap object and then makes an array containing that object. It makes an ImageAttribute object and sets its remap table to this array.
Now the program simply draws the image onto a new Bitmap, specifying the ImageAttribute object. That object automatically performs the color translation.
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Private Sub btnGo_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnGo.Click
Dim cm As New ColorMap
cm.OldColor = Color.FromArgb(255, _
Integer.Parse(txtFromR.Text), _
Integer.Parse(txtFromG.Text), _
Integer.Parse(txtFromB.Text))
cm.NewColor = Color.FromArgb(255, _
Integer.Parse(txtToR.Text), _
Integer.Parse(txtToG.Text), _
Integer.Parse(txtToB.Text))
Dim remap_table() As ColorMap = {cm}
Dim image_attr As New ImageAttributes
image_attr.SetRemapTable(remap_table, _
ColorAdjustType.Bitmap)
Dim bm_src As Bitmap = picSrc.Image.Clone
Dim bm As New Bitmap(bm_src.Width, bm_src.Height)
Dim gr As Graphics = Graphics.FromImage(bm)
Dim rect As Rectangle = _
Rectangle.Round(bm.GetBounds(GraphicsUnit.Pixel))
gr.DrawImage(bm_src, rect, 0, 0, bm.Width, bm.Height, _
GraphicsUnit.Pixel, image_attr)
picResult.Image = bm
gr.Dispose()
bm_src.Dispose()
image_attr.Dispose()
End Sub
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Note that this method only remaps exact color matches. If you change blue pixels with red, green, and blue components (0, 0, 255) to some other color, then a pixel with color (0, 0, 254) will not be changed even though the two colors look the same on the screen.
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