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

Image-Editing-in-VB.Net.jpg

For load an image in tool see this

how to Open an image

Image-Editing-tool-in-.Net.jpg

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

Image-Editing-tools-in-VB.Net.jpg

you can get brightness setting by above code