[RESOLVED] draw highlights over an image

[digitalShaman]

the is no "in between" and lockbits is part of the managed space. its just that a 24bpp bitmap is effectively an array of bytes, one byte for red, one for green and one for blue and that for each pixel. lockbits/scan0 allows you to directly access the RGB value of each pixel with the performance of a normal array read/write operation. i have not checked but i am sure that fastpix is actually using lockbits/scan0, but it encapsulates this away from you which is fair enough.

but now comes the clou. i realized that the correct way to do this is not accessing pixels but instead using a color transformation matrix when calling drawimage.
try this out:

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim img As New Bitmap("c:\kill\test.jpg")

        Dim matrix As New Imaging.ColorMatrix(
                    New Single()() {New Single() {1, 0, 0, 0, 0},
                                    New Single() {0, 1, 0, 0, 0},
                                    New Single() {0, 0, 0, 0, 0},
                                    New Single() {0, 0, 0, 1, 0},
                                    New Single() {0, 0, 0, 0, 1}
                                   })

        Dim Attributes As New Imaging.ImageAttributes
        Attributes.SetColorMatrix(matrix)

        Using g As Graphics = PictureBox1.CreateGraphics
            g.DrawImage(img, New Rectangle(0, 0, PictureBox1.Width, PictureBox1.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, Attributes)
        End Using
    End Sub