WebBrowser control not showing .jpg image c# winforms

I am making Html on runtime and i assign to a WebBrowser control using the code below:

 webBrowser1.Navigate("about:blank");
 HtmlDocument doc = this.webBrowser1.Document;
 doc.Write(String.Empty);
 webBrowser1.DocumentText = htmlText;

The issue is the WebBrowser Control does not show jpg image . On my html i am making user Images which reside locally on my computer so i am using the following code as a test :

SomeHtml="<img width=\"70\" height=\"50\"  src=\"" + picture + "\" />";

Where Picture is:

picture = "file:///" + startPath + "/" + picture.Replace("\\", "/");

The paths are all good i test it with two images both exist on the folder are the same pictures one is JPG and other is PNG.

Image paths:

/images/student_pictures/noimage.png
/images/student_pictures/noimage.jpg

For the above when i use .png the images appear on the WebBrowser control in case of .jpg i see the red cross.

Any suggestion ?