Transferring photo from iPhone to PC is not simple as copying from USB storage disc to computer. With iTunes, you can only transfer photo from your PC to iPod device and it's absolutely not allowed by contraries. So basically, the only way to transfer photo from iPhone to PC is to turn to help of iPod to PC Transfer.
There's a trial vertion of an iPod to PC Transfer named Cucusoft iPod to PC Transfer that will meet your need.
Guide: How to transfer photo from iPhone to PC?
Step 1: Connect iPhone to PC and Launch iPhone to PC transfer. Then the program will search the device automatically. If the device is enabled, the files (songs/movies/photos) will be shown in the list.
Step 2: Select photo to transfer from iPhone to PC, then Click the Export button.
Step 3: Choose transferring photo from iPhone to pc. After you clicking the Export button, the following window will pop up, you can choose transferring to computer or iTunes directly. You can set the output folder at Advanced->Options before transferring...
Step 4: When the transferring finished, the following window will pop up. It shows that how many files have been done. You can click the OK button to view the photo transfered from iPhone to pc.
Ok, you have transferred photo from your iPhone to PC, just enjoy it.
For iPod User: Transfer Photo from iPod to PC