Convert binary data from URL to an image file

Question

I read several articles on StackOverflow, but none of them seems to work in my case so here is the situation.

I have a webpage that is not under my control. It contains an image that is referenced in the markup as something like <img src="getimage.asp?pic=4c54aae0ea..." />. Given the URL of that image, I would like to download it, save it to disk and do something with it.

When I enter the URL directly in my browser I get a binary stream. This is the first load of characters.

ÿØÿàJFIFHHÿþLEAD Technologies Inc. V1.01ÿÛ„ÿÄ¢       }!1AQa"q2‘¡#B±ÁRÑð$3br‚     %&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyzƒ„…†‡ˆ‰Š’“”•–—˜™š¢£¤¥¦§¨©ª²³´µ¶·¸¹ºÂÃÄÅÆÇÈÉÊÒÓÔÕÖ×ØÙÚáâãäåæçèéêñòóôõö÷øùúw!1AQaq"2B‘¡±Á   #

How do I convert that data to an image using e.g. C# or any other language. Since I do not control the page I have no idea of how the data is encoded - so can I still decode it?

As can be seen from the first couple of characters, the string "LEAD Technologies Inc." is included in the data so I guess its not all image data. But at least, Chrome obviously knows how to decode it. A quick Google check reveals that "LEAD technologies" is an imaging SDK, but their website doesn't seem to offer much information about it's use and Im also not proficient in image manipulation. Any ideas would be appreciated.

Answer 1

The first couple of characters indicate that the response is probably an jpeg file interpreted as ASCII text. I guess the Content-Type header in the HTTP response has the wrong value, probably something like text/plain or text/html instead of image\jpeg. This makes Chrome display the image as plain text.

I don't think you have to convert the data. Just save the response stream to a file and you will have a proper jpeg file:

string url = "http://my-domain/getimage.asp?pic=4c54aae0ea...";
string fileLocation = @"C:\MyImage.jpg";

var client = new WebClient();
client.DownloadFile(url, fileLocation);

The reason I think that the response is probably jpeg, is that a jpeg file begins with 0xFFD8FFE0 which looks like ÿØÿà when displayed as ISO 8859-1 encoded text.