Doubt, I can not send the image.
Path: _img / _products / foto2-verde.png
<input type="radio" name="cor" id="verde" value="verde">
<img src="_img/_produtos/foto<?=$_POST['???']?>-<?=$_POST['cor']?>.png">
This last code has to be this: _img / _products / foto2-verde.png
The way it is, it works for me: _img / _products / photo ??? -verde.png