Lens Distortion Correction

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Most camera lenses distort the image and this can be corrected for using the lens distortion correction option which is available in proofs and when converting raw images. The before and after images below are from a picture taken with a Canon EOS 20D and Canon EF 15mm f/2.8 Fisheye lens (a lens popular for taking panoramas):

 

before
Uncorrected shot from Canon EOS 20D + EF 15mm Fisheye lens

after
The same shot after lens distortion correction with BreezeBrowser Pro

Photo copyright www.GlenfallHouse.org. Photo by www.BigGreenFurryThings.com

 

BreezeBrowser Pro uses the same lens calibration files as PTLens which was developed by Thomas Niemann (please visit http://epaperpress.com/ptlens for details). The profiles are stored in the PTLensProfiles folder where BreezeBrowser Pro is installed. Thomas Niemann is constantly adding to the database of lenses and the latest profiles can be downloaded from his site. The profiles are included with BreezeBrowser Pro with Thomas Niemann's kind permission.

 

The lens correction uses the shooting data in the file to automatically select the lens correction parameters. The first time you use lens distortion correction you need to setup a list of lenses and cameras. You can do this by enabling lens distortion correction and then pressing the setup button. The dialog below will be displayed:

lens_correction

 

Click on the list on the left to find your combination of camera body and lens and then double click on the entry to copy it to the list of selected lens definitions on the right. If you have digital cameras with different crop factors e.g. Canon EOS 350D (1.6 crop factor), Canon EOS-1D Mark II (1.3 crop factor) and Canon EOS 5D (1.0 crop factor), you will need to select the lenses for each camera model. The settings are saved when you exit BreezeBrowser Pro and so you only need to do this once.

 

The shooting data stores the lens focal length and the zoom range of the lens and BreezeBrowser Pro uses this to select the right lens correction factors. This means it isn't possible to distinguish between similar lenses such as the Canon EF 24mm f/1.4L USM and the EF 24mm f/2.8. Please only select the lenses you use to avoid confusion. BreezeBrowser Pro won't be able to apply the lens distortion correction if the image does not contain shooting data. Some image editors discard or damage the shooting data when saving images and so it may be necessary to use the EXIF copy tool to copy the shooting data from the original unedited file.