Photoshop 6 or later
Open the image in Photoshop and flatten any layers: Layer>Flatten Image.
Use File>Automate>Fit Image and type in the required image size: 1400 x 1050.
Use Image>Mode>RGB Color to convert the image to RGB if it was prepared in CMYK, Grayscale, Lab or Indexed colour.
Use Image>Mode>8 bits/channel to convert the image to 8 bits per channel.
Use Image>Mode>Convert to Profile and convert image to working space (For Photoshop CS2 onwards use Edit>Convert to Profile>Destination Space set to Working RGB).
Use File>Save As to save the image to disk or memory stick. Remember to rename it – Short Title followed by underscore (_) then your name e.g. The Tree_John Smith. If you are using a Mac, include the .jpg extension as appropriate. Format is jpeg maximum quality.