In a previous article I said this about previews:

2. Previews are never used for on-screen display except for slide shows

I'm wrong about this. Aperture does use the high resolution previews for regular screen display, but only if it thinks it can do better than the built-in library image and the master is off-line.

You can test this yourself. Set the preview quality to be 0 and the size to be 1280x1280. Take a project that uses big images and regenerate all the previews. Now move the project masters to another volume and take it off-line. Try displaying the images in the project at 100% and you will see the fuzzy image based on the built-in library image appear first and then the blocky low-quality preview replace it. If the master is on-line then the preview is not used -- or at least I have never been able to catch it using it with the technique just described.

However, this error does not change my advice. Most people don't need high resolution previews for every image. If you have off-line images and you need high resolution, then previews are most definitely for you.

Tags: Aperture, Previews