Or you could use an emulator program like bluestacks or nox and bypass this entirely.I'm not sure how many of you are aware of this method - I certainly wasn't - but this allows you to easily upload high-quality images directly to Instagram.com without using 3'rd party websites etc.
Step 1: Head over to Instagram. Make sure you're signed in. Should look like this:
Step 2: Right-click anywhere on the page and press "Inspect Element" On Chrome, you can press Ctrl+Shift+I. Should look like this:
Step 3: Locate the Mobile Phone/ Tablet icon at the top left of the console. Click it. It looks like this:
Instagram should now display the mobile version of the site.
Step 4: Press the camera icon at the bottom of the screen. If your image doesn't show up on the file browser, switch the file type from customized files to all files.
Use android emulators (look them up) and download instagram on them. Then you can change photos just like in your mobile.i think this method gone already. what new method upload post on pc , anyone?