Electronic Correction

Image quality displayed is not optimal when using electronic correction. Why electronic correction? In some case placing a projector in the optimal way is impossible (room too small, screen or surface too high, etc.). This is why projectors have adjustable foot and some screws on ceiling mount. But by using them some distortion will appear. To correct these distortion due to the tilt angle some functions are useful: o Geometric correction o Screen fit (not all projectors have this function) o Digital zoom (not all projectors have this function) Tilt angle Example:

Screen Fit is a function that corrects the projected image automatically. The projected image is fitted into the screen, and keystone correction and focus adjustments are performed automatically. In this situation when you use screen fit the projector does: Focus adjustment Finding screen edge (if not, calculate by sensor) Vertical keystone Horizontal keystone After that your screen is adjusted. Screen fit

When you press Screen Fit a message box appears. When you have centered the box on the screen repress screen fit and let the projector works. Press Esc button to finish the correction when a message box appears. When the projector detects any movement, for example when it is moved or tilted, it automatically corrects vertical and horizontal keystone distortion. This function is called Auto H/V-Keystone. To disable: SettingsKeystoneH/V KeystoneAuto H/V Keystone Off Screen fit utilisation Example:

The original position of the projector is wide. So when you « zoom » in reality you diminue the screen’s size !! In some case when you choose to project in “Tele” the brightness diminues about 40% ! Digital Zoom

Projector with 1:1.35 zoom ratio and 3000 lm brightness. Don’t forget the brightness formula: L m = LuxA x S Calcul to do to determine the final brightness, L m2 h1h1 h2h2 l1l1 l2l2 For minimum zoom (1.35) we know: L m1 = 3000 lumen h 1 = 1.35 x h 2 and l 1 = 1.35 x l 2 For maximum zoom (1) we search: L m2 = ???? lumen Hyp: luxA 1 and luxA 2 are equal. So: L m2 ÷ L m1 = S 2 ÷ S 1  S 2 ÷ S 1 = (l 2 x h 2 ) ÷ (l 1 x h 1 )  S 2 ÷ S 1 = (l 2 x h 2 ) ÷ (1.35 x l 2 x 1.35 x h 2 )  S 2 ÷ S 1 = 1 ÷ 1.35²  L m2 = L m1 ÷ 1.35² LuxA = Σ9lux ÷ 9 (luminance average of 9 measurement points) Digital Zoom: Example

The End