In the code I posted the two lines below are probably important. The first line below tells the browser what is being sent, and the second opens a jpg file on the SD drive for sending. Note in my code the browser does not know what is being sent until the file type header and file are sent. In the arduino IDE in the line below, the URL is high lighted and I just click on it to open the browser and down load the image.
client.println("Content-Type: image/jpeg");
File myFile = SD.open("HYPNO.JPG");
//address will look like http://192.168.1.102:84 when submited