I found this free online cross stitch chart maker that can convert your pictures into a chart. For fun, I put my photograph onto there to see what would happen. I had to mess with the slider bars to get it to look good and if I were to actually do this cross stitch craft, it would end up 18"x18" using Aida 11 count fabric. WAYYYY too big. (11"x11" with 18 count fabric) I can't even imagine the amount of hours to do it. But it CAN be done, and that's the point. Choose a simpler picture is my advice.
Here's the link to the chart maker:
And BTW, you can use it to chart other things too besides cross stitch!
Here's a snip of my photo charted: