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This chapter is from the book

Straighten the Picture

A common problem with photos is that they are crooked. The subject matter often determines if the uneven condition is noticeable or not. Generally speaking, close-up nature photos ( Figure 3.12 ) lack a horizontal reference and don't appear crooked.

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Figure 3.12 A nature photo rarely appears crooked.

Is the photo in Figure 3.13 crooked? There is no horizontal reference and any viewer looking a gas prices that low would not notice if it was crooked or not.

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Figure 3.13 Is this photo crooked? With gas that cheap—who cares?

Straightening out a photo is much easier with the new Straighten tool straightentool.jpg . Before beginning the exercise on page 47, you need to know a few things about the Straighten tool. To align an image horizontally, use the tool to draw a line in the image that should be horizontal. If there is no horizontal reference you can use a vertical reference; just hold down the Ctrl key and draw a line along something in the photo that should be vertical.

There are three options in the Tool Options bar that control what happens to the image after it is rotated: Grow Canvas to Fit, Crop to Remove Background, and Crop to Original Size. As you rotate any image, the dimensions of the photo increase or some pixels in the image must be cropped. Figures 3.143.16 on this page and the next show the effects of these options.

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Figure 3.14 The result of using the Grow Canvas to Fit Straighten tool option.

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Figure 3.15 The result of using the Crop to Remove Background option.

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Figure 3.16 The result of using the Crop to Original Size option.

Straightening a Crooked Photo

For our Straighten tool exercise I have a classic example of a crooked photo that needs to be straightened. The photo was taken from a car while waiting for a light to change.

  1. Open the image Crooked_photo.jpg from the Peachpit Press Web site.
  2. Select the Straighten tool (P) from the Toolbox. Change the option to Crop to Remove Background.
  3. Hold down the Ctrl key, drag a line like the green line shown in Figure 3.17 , and release. The Washington Monument ( Figure 3.18 , next page) appears straighter—or does it? In fact it is now leaning slightly to the right. Also notice the top of the obelisk is touching the top of the photo.
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    Figure 3.17 Ctrl-drag the Straighten tool along the center vertical line.

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    Figure 3.18 Now the monument is tilting the other direction.

  4. Undo the last action (Ctrl+Z) and apply the Straighten tool again by Ctrl-dragging a line as shown in Figure 3.19 , next page. Your end point should be almost half the distance between the starting edge and the middle. This time it works and the cap of the monument isn't touching the sky ( Figure 3.20 , page 49).
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    Figure 3.19 Ctrl-drag the Straighten tool along the center vertical line as directed.

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    Figure 3.20 Now the monument appears straight.

So, what happened during the exercise and how did I pick the vertical line that I had you use? First of all, the Washington Monument isn't crooked but it was near the edge of the landscape in the photo. Barrel distortion produced by the wide-angle lens makes the obelisk appear to be bending in just like the buildings on the edge of the Chicago street scene in Figure 3.21 , page 49. How did I pick the line to use? Experimentation. The Straighten tool works very fast, so it only took a few tries.

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Figure 3.21 Barrel lens distortion makes the buildings on the edge of a photo appear to be bending inward.

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