c is an example of capturing a screen shot of a web page from a url to generate a picture

using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Threading;
using System.Windows.Forms;
public class WebsiteToImage
{
private Bitmap m_Bitmap;
private string m_Url;
private string m_FileName = string.Empty;
public WebsiteToImage(string url)
{
// Without file 
m_Url = url;
}
public WebsiteToImage(string url, string fileName)
{
// With file 
m_Url = url;
m_FileName = fileName;
}
public Bitmap Generate()
{
// Thread 
var m_thread = new Thread(_Generate);
m_thread.SetApartmentState(ApartmentState.STA);
m_thread.Start();
m_thread.Join();
return m_Bitmap;
}
private void _Generate()
{
var browser = new WebBrowser { ScrollBarsEnabled = false };
browser.Navigate(m_Url);
browser.DocumentCompleted += WebBrowser_DocumentCompleted;
while (browser.ReadyState != WebBrowserReadyState.Complete)
{
Application.DoEvents();
}
browser.Dispose();
}
private void WebBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
// Capture 
var browser = (WebBrowser)sender;
browser.ClientSize = new Size(browser.Document.Body.ScrollRectangle.Width, browser.Document.Body.ScrollRectangle.Bottom);
browser.ScrollBarsEnabled = false;
m_Bitmap = new Bitmap(browser.Document.Body.ScrollRectangle.Width, browser.Document.Body.ScrollRectangle.Bottom);
browser.BringToFront();
browser.DrawToBitmap(m_Bitmap, browser.Bounds);
// Save as file? 
if (m_FileName.Length > 0)
{
// Save 
m_Bitmap.SaveJPG100(m_FileName);
}
}
}
public static class BitmapExtensions
{
public static void SaveJPG100(this Bitmap bmp, string filename)
{
var encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
bmp.Save(filename, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}
public static void SaveJPG100(this Bitmap bmp, Stream stream)
{
var encoderParameters = new EncoderParameters(1);
encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
bmp.Save(stream, GetEncoder(ImageFormat.Jpeg), encoderParameters);
}
public static ImageCodecInfo GetEncoder(ImageFormat format)
{
var codecs = ImageCodecInfo.GetImageDecoders();
foreach (var codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
// Return 
return null;
}
}

The method of invocation is as follows:

WebsiteToImage websiteToImage = new WebsiteToImage( "https://www.ofstack.com", @"D:\Some Folder\keleyi.jpg");
websiteToImage.Generate();

This USES the WebBrowser control, so you must reference the System.Windows.Forms namespace.