In versions prior to iAd Producer 4.0, importing standard resolution ("1x") and high resolution ("2x") image assets could sometimes behave inconsistently. With iAd Producer 4.0, image assets are now managed according to the following rules:

• High resolution files must have "@2x" added to the end of the filename (such as "image@2x.png").
• Files without "@2x" in the filename (such as "image.png") are considered standard resolution.
• Validation warnings will be issued for standard resolution images without a corresponding high resolution version.
• Validation warnings will be issued for high resolution images that are not exactly twice the width and twice the height of the standard  resolution version.

As in previous releases, the best practice is to create, import, and use both standard and high-resolution versions of all image assets.