I.R.I.S. Readiris 14 for Mac User Guide - Manual (Page 127)

How To
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 Drag the corners one by one in the direction of your text.
 Click Apply to deskew the image.
Tips for making digital camera images
 Always select the highest image resolution.
 Enable the macro mode of the camera to take close-ups.
 Enable the document mode of the camera (if any)
 Only use optical zoom, not digital zoom.
 Hold the camera directly above the document. Avoid
photographing documents at an angle.
 Produce stable images. Use a tripod if necessary.
 Disable the flash when photographing glossy paper.
 Avoid opening compressed camera images.