"Tint" property when drawing Image with VB.NET

Question

Given a color, how can I "tint" an image when I am drawing it into a picturebox with VB.NET?

Answer 1

You can use the ColorMatrix class to accomplish this:

    'Imports System.Drawing.Imaging
    ''' <summary>
    ''' Tints a bitmap using the specified color and intensity.
    ''' </summary>
    ''' <param name="b">Bitmap to be tinted</param>
    ''' <param name="color">Color to use for tint</param>
    ''' <param name="intensity">Intensity of the tint.  Good ranges are .25 to .75, depending on your preference.  Most images will white out around 2.0. 0 will not tint the image at all</param>
    ''' <returns>A bitmap with the requested Tint</returns>
    ''' <remarks></remarks>
Private function TintBitmap(b As Bitmap, color As Color, intensity As Single ) As Bitmap         
        Dim b2 As New Bitmap(b.Width,b.Height)

        Dim ia As New ImageAttributes

        Dim m As ColorMatrix 
        m = 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() {color.R/255*intensity, color.G/255*intensity, color.B/255*intensity, 0, 1}})

        ia.SetColorMatrix(m)
        Dim g As Graphics = Graphics.FromImage(b2)
        g.DrawImage(b,new Rectangle(0, 0, b.Width, b.Height), 0, 0, b.Width, b.Height, GraphicsUnit.Pixel, ia)
        Return b2

End Function

Then to use it, you can simply:

Dim b As Bitmap = New Bitmap(ofd.FileName)                        
PictureBox1.Image = TintBitmap(b,Color.Red,0.3)