button image as form input submit button?

You can also use a second image to give the effect of a button being pressed. Just add the "pressed" button image in the HTML before the input image:

<img src="http://integritycontractingofva.com/images/go2.jpg" id="pressed"/>
<input id="unpressed" type="submit" value=" " style="background:url(http://integritycontractingofva.com/images/go1.jpg) no-repeat;border:none;"/>

And use CSS to change the opacity of the "unpressed" image on hover:

#pressed, #unpressed{position:absolute; left:0px;}
#unpressed{opacity: 1; cursor: pointer;}
#unpressed:hover{opacity: 0;}

I use it for the blue "GO" button on this page

This might be helpful

<form action="myform.cgi"> 
 <input type="file" name="fileupload" value="fileupload" id="fileupload">
 <label for="fileupload"> Select a file to upload</label> 
 <br>
 <input type="image" src="/wp-content/uploads/sendform.png" alt="Submit" width="100"> </form>

Read more: https://html.com/input-type-image/#ixzz5KD3sJxSp

Late to the conversation...

But, why not use css? That way you can keep the button as a submit type.

html:

<input type="submit" value="go" />

css:

button, input[type="submit"] {
    background:url(/images/submit.png) no-repeat;"
}

Works like a charm.

EDIT: If you want to remove the default button styles, you can use the following css:

button, input[type="submit"]{
    color: inherit;
    border: none;
    padding: 0;
    font: inherit;
    cursor: pointer;
    outline: inherit;
}

from this SO question

You could use an image submit button:

<input type="image" src="images/login.jpg" alt="Submit Form" />