Perspective correction
When we take photographs of architectural objects, there may appear a problem of distorted perspective, which is particularly typical of images with dominant vertical lines and shapes. Although sometimes the effect of distorted perspective can contribute to the artistic merit of a photo, in most cases it spoils a general impression of the image.
It should be mentioned that perspective projection distortion is an inevitable phenomenon. It occurs in photographs when the film plane is not parallel to lines that are desired to be parallel in the photo. A common case is when a photo is taken of a tall building from ground level by tilting the camera backwards; the building appears to fall away from the camera.
Typical scenes that causes perspective distortion are: slanted trees, telephone poles, fence posts, lampposts, leaning buildings and structures, columns, vertical edges of walls and furniture.
Perspective correction or perspective control is a procedure for composing or editing photographs to better conform with the commonly accepted distortions in constructed perspective. The correction would:
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make all lines, which are vertical in reality, vertical on the image.
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make all parallel lines (such as four horizontal edges of a cubic room) cross in one point
Perspective projection distortion is a common problem in the world of modern photography. The popularity of amateur photography has made distorted photos captured with cheap cameras so familiar that many people do not immediately realize the distortion.
One of the ways to control perspective is to use perspective correction lens. But it can be expensive. Fortunately, today every entry-level photographers can easily correct distorted images in Adobe Photoshop, or other similar photo editing software. The process is easy, fast and effective.
How to correct perspective distortion in Photoshop:
Look at these two images: the first one has a distorted perspective while the second one has been corrected.
1. Open a distorted image in Photoshop, maximize the window and choose Select All (CTRL + A). It will look like this:
Remember to use CTRL + Z to cancel the previous action or Escape button to start over.
2. Choose in the menu bar: Edit – Transform – Perspective
3. Drug the upper left handle and move it to the left until the lines look vertical and parallel.
4. Press Enter when you’re satisfied with the results.
5. Note that on the photo above, the lines on the left look ok, while those on the right are still distorted. It is because the Perspective tool ties two opposite sides of the picture together.
If the photo is not equally distorted at each side, you can use a Skew tool: first Select All (CTRL + A) and then choose Edit – Transform – Skew
6. Drag the upper right handle to the right and up, and the left one to the left and up until the photo is better aligned.
7. When you are happy with the results hit Enter button.
Don’t be afraid to experiment with the other Transform Tools. In this image I also used a Scale Tool (Edit – Transform – Scale) to stretch out the tower.
Read Photography Perspective tutorial to understand what the perspective is and how it can be showed in an image to add a dramatic effect.
[tags]perspective distortion, perspective correction, Adobe Photoshop, perspective correction lens, digital cameras, photography tutorial[/tags]
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