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The calibration of my digital camera does not seem to be very good. In particular the automarked points are not consistently marked.

Some digital cameras and some office flat bed scanners perform an automatic operation called “unsharp masking”. This makes photographs seem sharper to us visually. Unfortunately this operation can greatly increase the noise and false edges in a scene like the calibration grid. It will be worse if the lighting is not strong and the contrast is low. The added image noise and false edges throw off the Camera Calibrator’s automatic marking algorithm because it does not see smooth black to white transitions in the image. This can cause the auto- marked points to be poorly marked, which in turn can cause a poor calibration or a calibration that fails altogether.

The solutions are:

  • Try turning down the sharpness setting on your digital camera or scanner.
  • If your digital camera has a monochrome (black and white) mode try that as it may reduce artifacts.
  • Pull the images into an imaging program like PhotoShop and do noise filtering and blurring. The images can look very blurry to a human and be quite acceptable to the Calibrator.
  • [for Pro 3 and Pro 4 only] Camera calibrations of digital cameras can also fail (given that the automarking looks good) if the initial guess at format size is very far off from reality. See the help file section called “Determining Digital and Video Camera Format Size”.