How Aperture displays photos in the Viewer

When a version needs to be displayed in the Viewer, Aperture does the following:

  • Aperture draws the thumbnail image (a JPEG image that is 1280 pixels in the longest dimension).

  • Aperture draws the JPEG preview, if present.

  • Aperture decodes the original and applies any adjustments to it.

Once the last step is completed, the adjustment controls become available. Because the JPEG preview is created with all the adjustments for that version, it appears onscreen faster than the adjusted original would. The result is a sharp preview image that appears quickly in the Viewer.