Hi nicejumay!
To have a better understanding of your issue, please let our Canon Forum members and our Subject Matter Experts know some basic information regarding your current setup.
Images on your EOS Rebel T4i screen may appear "better" due to camera settings, the application you're using on your computer to view them, your curren't video card setup on your computer, and several other factors.
First, please let us know if you're shooting in JPEG or RAW format on the EOS Rebel T4i. Additionally, if you're shooting in JPEG, what are your current "Image Quality" settings (Medium, High, etc...)?
When you open images on your computer, what application do you view them in?
Once we have some of this information, we're confident our Canon Forum members can provide you with some useful suggestions.
Thanks!
