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You can switch between manually correcting an image or using a stored profile if one is available for your camera and lens combination using the set of buttons shown here.

If you want to see the choice of cameras, lenses and focal lengths for each make, do not load an image file. First select the make, then a camera and then the lens and finally the focal length drop down boxes.

When an image is loaded, the programme attempts to read the EXIF (Exchangeable Image File Format) descriptive data written by most digital cameras to JPEG, RAW and TIFF files. If this can be found, the status bar beneath the image shows what can be read from the image file.

If the camera has a fixed lens, and if no telephoto or wide angle adapters are available for it, and if the profile is available, then parameters will be selected automatically. If not, then you must choose the nearest ones you can find from the available lists of profiles, or manually do your own calibration as shown in the next sections. 


A test image (test_grid.bmp) is installed with the programme which you may use for experimenting with altering calibration constants to see what they do.  It is not a substitute for a proper calibration target for calibrating a lens which is not in the PTLens database.

The figures show distortion deliberately introduced into the test image and subsequently removed.

If you have an image from a calibrated camera in JPEG or Tiff format which contains the required data and for which a profile is available, you can examine the calibration constants for this image by clicking on the Radial option when it is displayed.

If there is no profile available, but the image contains the required data which you can see on the status bar:

you may be able to find a nearly similar lens in the lens list whose calibration can be tried, altered and saved to a file for further use.