I did crawl the images in the Google Image Search window
but, the images are too small so I want to increased the size
I increased the size using PIL, but the picture is broken(Image quality is too low)
How can I increase the images size with good quality?
I used PIL this way
from PIL import Image
im = Image.open('filename')
im_new = im.resize((500, 500))
im_new.save('filename2')
No, I think you maybe get a wrong understanding of the real problem.
The images you got are just some thumbnails, so it contains little information. Your efforts to improve the image quality by some algorithm may be very hard to make a difference. Probably only by using some machine learning tricks can you make the photos a little nicer.
In my opinion, what you need to do is to get original images you got with Google search rather than use thumbnails. You can do this by do a lot more analysis with image search results. Good luck :)
