Mushrooms - examples 1
JPEG - original photo & cropped copy
Mushrooms - examples 2
PNG - original photo & cropped copy
Mushrooms - examples 3
Canvas - original size & three cropped sizes
Cropping methods. There are two methods to crop digital pictures. You can crop a JPEG in a program like Picasa or Paint. Then the results of cropping can be exported to a new file. The second method is cropping the JPEG (or PNG) in HTML Canvas.
The advantages of HTML Canvas. Cropping an image in Canvas can be done with a single source photo (in JPEG and PNG). Canvas nr. 1 represents the original sizes. Numbers 2-4 are cropped versions. But nr. 1-4 are produced by one JPEG source file.
Conclusion. Using Canvas on a website is a very good choice. You avoid placing multiple images on the server, including the original photo and the cropped versions of it. And secondly, you can easily adjust the values of the cropping without compromising the quality of the original JPEG.