Leveling Horizons using Photoshop's "Measure Tool" or "Ruler Tool"

by Hugh Stockton

If you think your horizon may not be level, or know it isn't and want to fix it, PhotoShop has the answer: the Measure Tool.

1. Right-click on the EyeDropper. On the dropdown, select the Measure Tool (in some versions of Photoshop, this is called the "Ruler Tool"). The cursor will change to a ruler with small "x".
2. Use that cursor to draw a line on the horizon, or any line you want to be horizontal. Or, you can trace a vertical line on anything you know should be vertical, such as a building (assuming that you have already corrected any perspective problems).
3. Then select Image, Rotate Canvas, Arbitrary. The "Angle" box will display how far from level your line is. If you Click OK, the picture will be rotated to make that line level. Click Cancel to skip it. I usually don't bother if it's less than 1/2 a degree.
4. If you did rotate the photo, you will probably want to use the crop tool to cut off the pieces of exposed canvas. Or, use the Clone tool to fill in the missing areas. You can also use Guides to crop after leveling.