As much crosstitch as I've done, I've never done one from a photo. I know there are computer programs you can buy to convert your own scanned photos into crosstitch patterns. I see them advertised in the back of the crosstitch and craft magazines all the time. Also there are companies you can pay to create a pattern from one of your photos......I think that's what the link is that Anno gave you up above.
I checked at JoAnne Etc. online and found a computer program that will convert a photo to a pattern:
http://www.joann.com/catalog.jhtml?CATID=54559&PRODID=57818&source=searchand that's only one of several.
Of course if you think you'd never use it again, it'd make more sense I guess to pay someone else to do it, than to struggle with trying to figure out the computer program....but if your daughter would get into using the program to create patterns it might be worth the $$$$.