Operation Manual

Working with bitmaps | 521
Correcting camera lens distortions
With photos that contain camera lens distortions, it is recommended that you start with correcting the lens distortion. You can correct two
types of lens distortions, which make straight lines in photos appear curved: barrel and pincushion. Barrel distortions make photos appear
pushed out at the center. Pincushion distortions make photos appear pushed in at the center.
Rotating and previewing
The Straighten image dialog box lets you rotate an image by moving a slider, typing a rotation angle, or using the arrow keys. You can
specify a custom rotation angle from -15 to 15 degrees.
You can use the preview window to dynamically preview the adjustments that you are making. If you want to change the orientation of the
image before straightening it, you can start by rotating the image 90 degrees clockwise and 90 degrees counterclockwise.
A grid is displayed in the preview window to help you straighten the image. You can make more precise adjustments by controlling the cell
size of the grid. To heighten the contrast of the grid against the colors of the image, you can change the grid’s color. You can also hide the
grid if you want to preview the final result without the gridlines. In addition, you can zoom in and out, and pan the image in the preview
window to evaluate the results.
Cropping
By default, the straightened image is cropped to the cropping area that is displayed in the preview window. The final image has the same
aspect ratio as the original image, but it has smaller dimensions. However, you can preserve the original width and height of the image by
cropping and resampling the image.
You can also produce an image at an angle by disabling cropping and then using the Crop tool to crop the image in the drawing window.
To straighten an image
1 Select an image.
2
Click Bitmaps Straighten image.
If the image has a lens distortion, move the Correct lens distortion slider to the left to correct a barrel distortion or to the right to
correct a pincushion distortion.
3 Move the Rotate image slider, or type a value between 15 and -15 in the Rotate image box.
4 If necessary, move the Grid slider to adjust the size of the grid cells.
5 To crop and straighten the image, enable the Crop image check box.
The image is cropped to preserve the aspect ratio of the original image, which means that the final image is smaller than the original
image.
If you want to preserve the width and height of the original image, enable the Crop and resample to original size check box. The final
image is resampled.
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Correcting perspective distortions
Premium feature
You can correct perspective distortions in photos that have straight lines and flat surfaces such as architectural photos and photos of
buildings.
Perspective distortions usually occur when you take pictures of tall or wide objects, and the camera sensor is at an angle to the objects. As a
result, the photographed objects may appear to be leaning or to be at an angle. Adjusting the vertical perspective helps straighten leaning
objects; adjusting the horizontal perspective helps with angled objects. Often, you may need to adjust both the vertical and horizontal
perspectives for best results.