Resample Images

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?

This function will do the job:

Code:

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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

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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:

Code:

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

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Multiplying the two equations to eliminate w we get:

Code:

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h^2 = aspect ratio * maximum number of pixels

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hence the square root.

BB