If you select a very large image and use the Open With External Editor command, you may get an alert message saying that the image can't be found. If your designated editor was Adobe Photoshop CS2, for example, the message would say:
Edit in Adobe Photoshop CS2 Alert
The selected image file could not be located and so cannot be exported to Adobe Photoshop CS2.
The text of this message does not state the actual reason, but this happens because there is a size limit for images being sent to an external editor. The size limit varies with your system configuration and is well in excess of file sizes created by supported digital cameras. You might see this, for example, if you import a very large scanned image. In general, images up to about 250MB should work on any Aperture-supported system.
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