Image Editing Tool in VB.Net: Part 4

In last three articles  we have dicussed about how to load an image in our windows form, how to resize that image and how to crop an image see this:

Part1: Open an image

Part2: Resizing image

Part3: Cropping image

Now next article of this series describes how to set the brightness of an image.

For this we can use concept of colormatrix class of system.Drawing namespace.ColorMattrix defines a 5 x 5 matrix that contains the coordinates for the RGBAW space.
 
You can go msdn for understanding concept of color matrix

http://msdn.microsoft.com/en-us/library/system.drawing.imaging.colormatrix.aspx

http://msdn.microsoft.com/en-us/library/system.drawing.imaging.colormatrix(v=VS.71).aspx

First design brightness tab like this layout



For load an image in tool see this

how to Open an image

code:

Write code on the trackbar_scroll event

Dim value As Double = TrackBarBrightness.Value * 0.01F

DomainUpDownBrightness.Text = value 

   

This line set the brightness value of image in domainUpDown control withrange -100 to 100.

And below we demine single type array in 5 x 5 matrix

       

        Dim colorMatrixElements As 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() {value, value, value, 0, 1}}

 

Define colormatrix

 

        Dim colorMatrix As New Imaging.ColorMatrix(colorMatrixElements)

 

  An ImageAttributes object maintains color and grayscale settings for five adjustment categories: default, bitmap, brush, pen, and text. For example, you can specify a color-adjustment matrix for the default category, a different color-adjustment matrix for the bitmap category, and still a different color-adjustment matrix for the pen category.

 

        Dim imageAttributes As New ImageAttributes()

 

        imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap)

 

        Dim _img As Image = Img 'PictureBox1.Image

        Dim _g As Graphics

        Dim bm_dest As New Bitmap(CInt(_img.Width), CInt(_img.Height))

        _g = Graphics.FromImage(bm_dest)

 

 

        _g.DrawImage(_img, New Rectangle(0, 0, bm_dest.Width + 1, bm_dest.Height + 1), 0, 0, bm_dest.Width + 1, bm_dest.Height + 1, GraphicsUnit.Pixel, imageAttributes)

        PictureBox1.Image = bm_dest

 
 

you can get brightness setting by above code