1. Scale image by .NET to produce the best quality
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/images"), fileName), imageFormat)
Note the bold code above, It will produces the best quality image when you try to Zoom or Scale to smaller image.
Beside, I found another way to scale smaller image but, using CSS and HTML only. THe quality is good.
