Is is possible to crop an image after uploading

Untested, but I believe this should work:

jQuery(document).ready(function (){
    jQuery(".select-image").click(function() {
        var custom_uploader = wp.media({
            title: 'Selecteer een afbeelding',
            button: {
                text: 'Selecteer'
            },
            multiple: false
        });
        custom_uploader.on('select', function() {
            custom_uploader.Jcrop();
        });
        custom_uploader.open();
    });
});