PG-C20XE (serv.man3). Service manual supplement. Covers the color irregularity correction system for the above models. - Sharp Projector Service Manual (repair manual). Page 13

Here are tips and hints in taking pictures with the digital camera.
Proper shooting produces precise corrections.

If the images downloaded are not recognized in STEP 2 or if the correction results are poor, check the
following points.

This system provides automatic recognition of the image frame.
The frame is determined by the luminance difference between a projected image itself and its dark
surroundings.
The frame recognition depends on the Threshold Value setting on the main screen.

Camera’s shooting area

Space to be 10 dots or wider (dots = pixels on the computer screen)

(Make sure the dark zone around the projected image is sharp enough.)

Minimum size.    To be more than a quarter vertically and horizontally.

Position the camera so that the projected image should be within this frame

Space of more than 10 dots

More than a quarter

Projected image