Q: why does picture quality changes after downloading from website? I am writing parsing code to extract images from website. Its based on taking  tags and getting the source link of the image.
If we take website BBC as example (news article), the source of the first picture they show is (link) but if i open that link directly, the quality of the images changes drastically. 
I am not able to understand how BBC shows a good quality of the picture with same link and how I am not able to get same quality BBC shows by downloading.
Can you tell me how I can get the same quality picture by downloading ?

A: The actual picture is here:
http://news.bbcimg.co.uk/media/images/61576000/jpg/_61576754_015313589.jpg
The URL you gave is just the thumbnail image.
There is no trickery here.  You're just looking at the thumbnail instead of the image.  Because it's some fancy JavaScript gallery they're using, you have to reverse engineer how it works and inspect the actual DOM (as I did) to get the real image URLs.
