Crop a non-clipped image
Select the crop tool, and then drag handle inside to create a rectangular crop mask.
Alternatively, press O to display the crop dialog box, and then drag or size the crop as you want.
Uncrop a non-clipped image
On the Images menu, click Uncrop all.
Alternatively, with the crop tool, drag any handle of the image outside as much as possible, or with the polygon tool , click to select any vertex of the irregular mask and drag it outside of the image, as much as possible. Delete all the vertexes except the basic four.
Notes
•In the Crop dialog box, you also see the actual zoom percentage (Skew - if the image was distorted, the values in the H: and V: will be different), the original resolution, and the actual resolution.
•On a clipped imaged (images with clipping path), the crop mask will be shown as rectangular.
•It is not possible to uncrop image cropped in an oval mask, maintaining the shape form - the uncropped part will be rectangular.
To learn more see also