A guide to transfer picture form iPhone to computer is already available Here and today i received a comment that how can i transfer pictures form computer to iPhone 4. Follow the given steps below to transfer pictures form your computer to iPhone.
Connect your iPhone with computer and run iTunes.
Select your device from left panel under “Devices” section
Click on Photos
Check the “Sync Photos from” check box and click on drop-down menu to Choose a pictures folder from computer that you want to transfer to iPhone.
Finally click on Apply or Sync button.
When iTunes finish the syncing process.
Open Photos app from iPhone to view pictures that you have transferred from computer to iPhone.