Losing picture qaulity when resizing on the fly!

Question

User944361798 posted
Hi,

I am resizing an image from (1024 X 768) to (450 X 338), but losing so much picture qaulity, because of the image becoming blurry!

Anything I can do better to hold the image qaulity when resizing the image? 

Thank you for any help in advance!

Dim objImage, objThumbnail As Image

Dim shtWidth, shtHeight As Short

objImage = objImage.FromFile(Server.MapPath("/Template/images/" & FileName))

thisFormat = objImage.RawFormat

' set width

shtWidth = 150

' Work out a proportionate height from width

shtHeight = objImage.Height / (objImage.Width / shtWidth)

' Create thumbnail

objThumbnail = objImage.GetThumbnailImage(shtWidth, shtHeight, Nothing, System.IntPtr.Zero)

' Send down to client

objThumbnail.Save(Server.MapPath("/Template/images/thumbnails/") & FileName, thisFormat)

' Tidy up

objImage.Dispose()

objThumbnail.Dispose()

Answer 1

User1152494133 posted
Don't trust the GetThumbnailImage() for anything other than, well, small thumbnails (i.e., it works great for images around 150px, no so great for things around 450px).  Create a new image of the smaller dimensions (450x338) and draw the original image to the new image with scaling.

I posted some sample code here: http://forums.asp.net/958348/ShowPost.aspx

Answer 2

User944361798 posted

Great! Thanks Jason, it works just fine, here is my (your) solution :)

Dim Pic As Image = Image.FromFile(Server.MapPath("/Template/images/" & FileName))

Dim thisFormat = Pic.RawFormat

Dim ImageWidht As Integer = 450

Dim ImageHeight As Integer = Pic.Height / (Pic.Width / ImageWidht)

Dim NewPic As Bitmap = New Bitmap(ImageWidht, ImageHeight)

Dim Gr As Graphics = Graphics.FromImage(NewPic)

Gr.DrawImage(Pic, 0, 0, ImageWidht, ImageHeight)

NewPic.Save(Server.MapPath("/Template/images/normal/") & FileName, thisFormat)

Gr.Dispose()

NewPic.Dispose()

Pic.Dispose()