Resample Images

[kaliman79912]

Hello,

I am using VS2010 and have an application that lets the user search for an image to store on a SQL database. I want to be able to reduce the size of the image when it passes certain size for obvious reasons.

Is there a way I can do this in runtime?

[boops boops]

This function will do the job:

Private Function SizeLimitedImage(image As Image, maxPixels As Integer) As Image
	If image.Width * image.Height > maxPixels Then
		Dim aspectRatio As Double = image.Height / image.Width
		Dim targetHeight As Integer = CInt(Math.Sqrt(aspectRatio * maxPixels))
		Dim targetWidth As Integer = CInt(maxPixels / targetHeight)
		Return New Bitmap(image, targetWidth, targetHeight)
	Else
		Return image
	End If
End Function

The logic of this is that you want the image to keep the same shape, so if w is the target width and h is the target height:

h/w = aspect ratio (= image height / image width)
w*h = maximum number of pixels

Multiplying the two equations to eliminate w we get:

h^2 = aspect ratio * maximum number of pixels

hence the square root.

BB