High Quality Full Screenshots VB.Net - vb.net

Question

I'm trying to add a feature to my program to take a full screenshot of the users screen when they click a button. I got the program to take the screenshot and open a file dialog box to save it, the saving works. The issue is that no matter how I save the screenshot, the saved image has significant quality loss and pixelates around text and stuff. This is a massive issue because I need the image to save exactly as it is seen on the users screen, I cannot have ANY quality loss at all. I tried to save the image as a jpg and a png and both gave me quality loss. I was wondering if anyone could point me towards some code or a method that would allow me to save the screenshots at the same quality as the users screen. I would like to save the image as a JPG or a PNG if possible. Any help would greatly be appreciated!

Answer 1

Get the image in Bitmap format and save it as bmp.
Private Function TakeScreenShot() As Bitmap
Dim screenSize As Size = New Size(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
Dim screenGrab As New Bitmap(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
Dim g As Graphics = Graphics.FromImage(screenGrab)
g.CopyFromScreen(New Point(0, 0), New Point(0, 0), screenSize)
Return screenGrab
End Function

Answer 2

For starters, JPEG images use a lossy compression algorithm so you tend to lose quality when you save in that format. It is preferable to save as Bitmap (BMP), which is uncompressed, or PNG, which uses a lossless compression.
Here is code to copy the working area of the screen to a PNG Image.
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
'the working area excludes all docked toolbars like taskbar, etc.
Dim currentScreen = Screen.FromHandle(Me.Handle).WorkingArea
'create a bitmap of the working area
Using bmp As New Bitmap(currentScreen.Width, currentScreen.Height)
'copy the screen to the image
Using g = Graphics.FromImage(bmp)
g.CopyFromScreen(New Point(0, 0), New Point(0, 0), currentScreen.Size)
End Using
'save the image
Using sfd As New SaveFileDialog() With {.Filter = "PNG Image|*.png",
.InitialDirectory = My.Computer.FileSystem.SpecialDirectories.Desktop}
If sfd.ShowDialog() = Windows.Forms.DialogResult.OK Then
bmp.Save(sfd.FileName, System.Drawing.Imaging.ImageFormat.Png)
End If
End Using
End Using
End Sub

Answer 3

.Net usually saves the file in 96dpi, so using following code you can save the file in higher resolution with Jpeg or other format.
'Create a new bitmap
Using Bmp As New Bitmap(800, 1000, Imaging.PixelFormat.Format32bppPArgb)
'Set the resolution to 300 DPI
Bmp.SetResolution(300, 300)
'Create a graphics object from the bitmap
Using G = Graphics.FromImage(Bmp)
'Paint the canvas white
G.Clear(Color.White)
'Set various modes to higher quality
G.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic
G.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
G.TextRenderingHint = Drawing.Text.TextRenderingHint.AntiAlias
'Create a font
Using F As New Font("Arial", 12)
'Create a brush
Using B As New SolidBrush(Color.Black)
'Draw some text
G.DrawString("Hello world", F, B, 20, 20)
End Using
End Using
End Using
'Save the file as a TIFF
Bmp.Save("c:\\test.Jpeg", Imaging.ImageFormat.Jpeg)
End Using

Answer 4

I've found that adding 3 lines to the above code significantly improves the quality of the image
var graphics = Graphics.FromImage(theRequestedAllocatedImage);
graphics.CompositingQuality = CompositingQuality.HighQuality;
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.SmoothingMode = SmoothingMode.HighQuality;
// Then call
graphics.CopyFromScreen(..)

Answer 5

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim screenSize As Size = New Size(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
Dim screenGrab As New Bitmap(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
Dim g As Graphics = Graphics.FromImage(screenGrab)
g.CopyFromScreen(New Point(0, 0), New Point(0, 0), screenSize)
PictureBox1.Image = screenGrab
PictureBox1.Image.Save("c:\picture.bmp")
End Sub