If you double-click on the Zoom tool (its icon looks like a magnifying glass) in the Toolbox, your image zooms to a 100% actual size view. You can also press Command-1 (PC: Ctrl-1) to get that same 100% view, or press Z to get the Zoom tool and then click on the 100% button up in the Options Bar, but that’s a lot slower than just double-clicking on the Zoom tool in the first place.
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