I have uploaded an image to Amazon S3 storage. But how can I access this image by url? I have made the folder and file public but still get AccessDenied error if try to access it by url https://s3.amazonaws.com/bucket/path/image.png
S3 usually 'just works' - upload the file, set the permissions, and visit the URL. If it doesn't (and their service is functioning) the problem is usually either the wrong URL or the browser cache.
I would really suggest using a program (such as those above) and copying and pasting the URL for your tests - it greatly reduces the chance of the URL being incorrect. If the above don't help, you might need to provide a bit more information so that the problem can be diagnosed.