html5 display as image rather than “choose file” button

You have to use Javascript Filereader for this. (Introduction into filereader-api: http://www.html5rocks.com/en/tutorials/file/dndfiles/)

Once the user have choose a image you can read the file-path of the chosen image and place it into your html.

Example:

<form id="form1" runat="server">
    <input type="file" id="imgInp" />
    <img id="blah" src="#" alt="your image" />
</form>

Javascript:

function readURL(input) {
    if (input.files && input.files[0]) {
        var reader = new FileReader();

        reader.onload = function (e) {
            $('#blah').attr('src', e.target.result);
        }

        reader.readAsDataURL(input.files[0]);
    }
}

$("#imgInp").change(function(){
    readURL(this);
});