You can capture the onchange event of the file input field in JS.
Add an Action button to your form that triggers the microflow, set the style to "display: none;" and give it a class to identify it, e.g. 'myButton'
Add this javascript (with jquery) to your page, using the HTMLSnippet widget from the appstore:
$('input[type=file]').change(function(e) { $('.myButton').click(); });
As the image uploader does not support an on change flow there is no simple way to accomplish what you're asking. Of course you can easily add a cropping flow to your save button, but that will obviously only take effect after the page is closed, not directly after upload.
If you don't mind getting your hands dirty you could try implementing your own custom widget, but that would require JavaScript knowledge. Alternatively, you could take a look at the Image Crop widget in the app store, although I fear that is going to fall short of what you are looking for.