The effect of contrast variation on task performance in video evaluation

Luminosity and brightness of the organs viewed on the screen are important for orientation during teleoperating. They can impair the precision of our orientation ability.

The way in which organs scatter light during laparoscopic operation was detected and analyzed by means of reflection spectrophotometry with the Photoshop program package (ADOBE). The arithmetical skill was measured during different illumination conditions of the screen created randomly, using values of the liver, gallbladder, and omental fat.

Separate human tissues and organs could be divided on the basis of their luminosity into three basic groups: the luminous tissues such as fat, the stomach, and the bowel; medium-luminous organs such as diaphragm and gallbladder; and dark, mostly parenchymatous organs such as the liver and the spleen. The most luminous tissue illuminated the screen intensely. In experiments the hyperillumination impaired arithmetical skills of 15 volunteers. The errors appeared constantly and the time needed to count the generated points was significantly longer when 40% of intensively illuminated view was exceeded.

A situation may occur wherein the imaging system lacks the capacity to transmit needed optical information. Intense brightness of the screen may suppress surgical skills during teleoperating. Critical limit was achieved in our experiment with 40% of the view illuminated by omentum fat. This limit can be important for robotic surgical systems such as automated robotic camera control.