Here's working code
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<asp:Image ID="Image1" runat="server" ImageUrl = "~/Jellyfish.jpg" Height = "400px" Width = "400px"/>
<br />
<asp:Button ID="btnGenerate" OnClick = "GenerateThumbnail" runat="server" Text="Generate Thumbnail" />
<hr />
<asp:Image ID="Image2" runat="server" Visible = "false"/>
</form>
</body>
</html>
NameSpace
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
Code
protected void GenerateThumbnail(object sender, EventArgs e)
{
string path = Server.MapPath("~/Jellyfish.jpg");
System.Drawing.Image image = System.Drawing.Image.FromFile(path);
using (System.Drawing.Image thumbnail = image.GetThumbnailImage(100, 100, new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback), IntPtr.Zero))
{
using (MemoryStream memoryStream = new MemoryStream())
{
thumbnail.Save(memoryStream, ImageFormat.Png);
Byte[] bytes = new Byte[memoryStream.Length];
memoryStream.Position = 0;
memoryStream.Read(bytes, 0, (int)bytes.Length);
string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);
Image2.ImageUrl = "data:image/png;base64," + base64String;
Image2.Visible = true;
}
}
}
public bool ThumbnailCallback()
{
return false;
}
