image quality lost on resize asp.net

[Lomex]

I'm building an app where the user can upload an image and the app will resize the image to the appropriate size. When this happens, once the image gets resized, the image quality degrates and looks crappy... Can anybody help me out?

MY CODE

'comes from a popup box where user selects the file

Dim img As System.Drawing.Image = System.Drawing.Image.FromStream(.InputStream)

Dim imageFormat = img.RawFormat

Dim thumbSize As New Size

thumbSize = NewthumbSize(img.Width, img.Height)

Dim imgOutput As New Bitmap(img, thumbSize.Width, thumbSize.Height)

imgOutput.Save(Path.Combine(Server.MapPath("../photo/imagesileName), imageFormat)

'this function finds the correct multiplier to resize the image

Function NewthumbSize(ByVal currentwidth, ByVal currentheight)

Dim tempMultiplier As Double

'check to see if image is portrait or landscape

If currentheight > currentwidth Then

'check to see if image height is smaller then what we want

If currentheight < 400 Then

tempMultiplier = 1 'don't change the image size

Else

tempMultiplier = 400 / currentheight

End If

Else

'check if width of image is smaller then what we want

If currentwidth < 450 Then

tempMultiplier = 1 'don't change the image size

Else

tempMultiplier = 450 / currentwidth

End If

End If

Dim NewSize As New Size(CInt(currentwidth * tempMultiplier), CInt(currentheight * tempMultiplier))

Return NewSize

End Function

[Tim Dorr Veteran]

It's probably not doing any resampling. Can you resample the image with any of the functions?

[Lomex]

new to this resizing stuff, what is resampling?

[Lomex]

Well, after reading thousands of posts on image resizing, one of them helped! This is what had to bee added to the code

Dim fileName As String = albumlist.SelectedValue & "_" & currentDate & fileExtension

' Create image object from upload stream

Dim img As System.Drawing.Bitmap = System.Drawing.Bitmap.FromStream(.InputStream)

Dim imageFormat = img.RawFormat

Dim thumbSize As New Size

thumbSize = NewthumbSize(img.Width, img.Height)

'Thumb-nail the image to the new size

Dim imgOutput As New Bitmap(img, thumbSize.Width, thumbSize.Height)

'**************THIS HAD TO BE ADDED!!*****************

Dim myresizer As Graphics

myresizer = Graphics.FromImage(imgOutput)

myresizer.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic

myresizer.DrawImage(img, 0, 0, thumbSize.Width, thumbSize.Height)

'****************************************************

'Save original image

imgOutput.Save(Path.Combine(Server.MapPath("../photo/imagesileName), imageFormat)