Our club's projector has a resolution of 1920 x 1080 pixels, so your image should be sized to fit within this area. 

The best way is to use your image manipulation software such as Photoshop or Lightroom to size the image when you are preparing the image and then perform any sharpening operation after resizing. 

You can also get an image resizer "add-on" for Windows 7 and later. You can download the add-on here.

With the add on installed, you can right click images in Explorer on Windows and you'll see Resize Pictures option. Select that option and make sure the Large button is checked; the Large setting is exactly right for our projector. Click OK and copies of the selected images will be made that are the correct size - you'll see the new image files with names such as _DSC5313 (Large).jpg.