Message-ID: <38823762.2F348EA9@midcoast.com.au> Date: Mon, 17 Jan 2000 09:25:54 +1100 From: "Paul B. Webster VK2BZC" Reply-To: paulb@midcoast.com.au Organization: Webster Medical Pty. Ltd. http://www.midcoast.com.au/~paulb/ X-Mailer: Mozilla 4.06 [en] (Win95; I) MIME-Version: 1.0 To: PICLIST@MITVMA.MIT.EDU Subject: Re: [OT] Human visual response (was: anode drivers for LED) References: <00dd01bf5d53$9955f7c0$2046b5d1@coyote.dnvr.uswest.net> <00d101bf5fa4$4f6a3920$0100007f@oemcomputer> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit andy howard wrote: > Talbot's law. Named after the English physicist and photographer, > William Henry Fox Talbot (1800-1877), who discovered that when the > cycle of a flickering light reaches so high a rate that it perceived > as being continuous, its apparent brightness is equal to the mean of > the brightness of the complete flicker cycle. Also known as the > Talbot-Plateau law, after Talbot and the Belgian physicist Joseph > Antoine Ferdinand Plateau (1801-1883). What you perceive is the average for frequencies above teh "flicker" or "fusion" frequency. > Weber's law. Named after the German psychophysicist, Ernst > Heinrich Weber (1795-1878), who discovered that the just-noticeable > differences in the intensity of various stimuli are proportional to > the intensity of the original stimulus. For instance, if a 100 watt > light must be increased by 5 watts in order for the difference to be > perceptible, then an increase of 50 watts would be necessary for the > change in a light of 1000 watts to be perceptible. The eye's perception of brightness is logarithmic. That's as I said, but it's a real neat reference, thanks. -- Cheers, Paul B.