In this week’s free Deke’s Techniques video, Deke goes in search of undersea treasure. Well, actually the treasure wasn’t that hard to discover—-the guide on the catamaran in St. Thomas was literally yelling, “Over here. There’s a sea turtle right down there.” But thanks to Deke’s valiant free-diving effort, his quick-thinking use of flash, and a hidden feature of Photoshop’s Auto-Levels command, he’s able to uncover the diamond in the rough that’s lurking just under the surface of this vacation photo:

I’d argue that 9% of this technique is achieved via one single command in Photoshop. As long as your photo has some information in the red channel, you can use this technique. Read on to see how to do just that: 

0) Use the flash to bring back some of the red-through-yellow light.

Natural sunlight has a habit of getting filtered by the sea, and the loss of red, then orange, then yellow light pretty quickly as you descend to the depths. So use the flash on your camera to put some of it back.

1) Check to see that there is at least some information in the Red channel.

If this technique is going to work, you’ll need some information in the red channel. As you can see in Deke’s image, it’s not overflowing with detail, but there is something there to work with.

2) Optional: Change the Canvas Size.

In Deke’s case, he wanted to change the orientation and composition of his image. So the first thing to do was to make the Background layer a free-floating (ha!) layer then converting it to a smart object. When you change the Canvas Size (by choosing Image > Canvas Size) to something smaller than the original image, Photoshop will warn that it’s going to clip the image. But since it’s already a smart object, that just isn’t true.

3) Transform the angle and size.

Deke brings our subject back on to the new smaller canvas by evoking the Transform command (Ctrl-T/Command-T), making the turtle a bit smaller, and changing his angle in the composition.

4) Optional: Fill in the naked corners.

When the image is rotated, it leaves some gaps in the lower-left and upper-right corners. The Spot Healing Brush, set to Content-Aware and Sample All Layers in the options bar, makes quick work of this.

5) Totally Not Optional: Apply a Power Auto-Levels layer.

The core of this technique is to leverage a mildly obscure option for applying a Layers adjustment. After creating the adjustment layer (click the black/white icon at the bottom of the Layers panel), Option-click (Alt-click) the Auto button in the Properties panel.

6) Choose to Enhance Per Channel Contrast.

In the dialog box that ensues, choose the Enhance Per Channel Contrast option in the Algorithm section. While you’re at it, check the Snap Neutral Midtones check box as well. The results are immediately transformative.

7) Adjust the Levels to taste.

You can start with the Auto settings, then continue to adjust the Levels from there. You can even adjust the individual color channels as Deke demonstrates in the movie. In the end, this turtley treasure is revealed.

Check out the video to see this in action and learn more about how and why it works (or at least, might work, in the right circumstances).

If you’re a member of lynda.com, Deke has an exclusive movie this week that shows you how to further polish up this gem. If you’re not a member, you can get a free week’s trial at lynda.com/deke, which entitles you to access the kajillions of training videos at lynda.com for a week.