This is a testing site only. See the live Public Lab site here »


intensity
intensity


Author Comment Last activity Moderation
stoft "Ah, good. Glad you could view the additional data and figured it out. " | Read more » almost 5 years ago
Tehnicni "How a stupid mistake. I checked linearity of all 3 cameras at three points, thinking that it have an exponential dependency, which is not true, the..." | Read more » almost 5 years ago
stoft "Yes, clearly all but the last image shows compression in the Green (and Red though less). Because the process of spectral data from a webcam does n..." | Read more » almost 5 years ago
Tehnicni "I also tried the third webcam, cheap Chinese. White Balance: R and G at max, B in the middle. Gama 2, Exposuer manually Measured at different..." | Read more » almost 5 years ago
stoft "The camera's I've used seem different in this effect but you might try to hunt down the technical data sheets from the Mfg -- sometimes they have a..." | Read more » almost 5 years ago
Tehnicni "I'm using wery old cheap webcam with all controll on manual and get same result with Logitech C525 also in manual mode. I checked lineariti on all ..." | Read more » almost 5 years ago
stoft "@Tehnicni, I'd agree that any detector-specific non-linearity is likely very small compared with the effect you've presented. I'd guess the more li..." | Read more » almost 5 years ago
Tehnicni "Question for @stoft. According to my measurements, the CMOS sensor has some sort of blooming effect before saturation. I tested my webcam with whit..." | Read more » almost 5 years ago
stoft "This is and interesting observation and thought experiment. And I'd agree that controlling a light source's intensity while monitoring the camera's..." | Read more » over 6 years ago
stoft "@viechdokter yes, having a stable source helps isolate the noise source. I chose the Solux as I could measure the current as an independent check o..." | Read more » over 6 years ago
viechdokter "Ooops! Guess I tried to re-invent the bicycle here, huh? Looks like all my thoughts have been thought before - and many more... ;-) Will read it ..." | Read more » over 6 years ago
warren "https://publiclab.org/notes/stoft/03-06-2015/plab-3-gain-correction See the comments! " | Read more » over 6 years ago
warren "Hi! Yes indeed, see @stoft's work on gain control; we're trying to generalize his work for other light sources, and also develop it into a Spectral..." | Read more » over 6 years ago
viechdokter "BTW I wonder if we could find out more about the effects of the camera if you could do this same setup plus statistics again let's say with a green..." | Read more » over 6 years ago
viechdokter "For anyone who is interested: https://publiclab.org/notes/viechdokter/04-15-2016/thinking-about-a-more-stable-spectrometer " | Read more » over 6 years ago
stoft "Jeff; I'm glad I was clear. The mechanics is like the rest; it starts with the objective / spec that it is an optical device. That immediately rule..." | Read more » over 6 years ago
warren "Thanks, Dave, very helpful answers. I understand what you're saying about the difficulty of structuring a measurement of structural stability -- I'..." | Read more » over 6 years ago
viechdokter "Here is what happened: The spectrometer slit was not in the center of the light beam but a little off-center. So when it was closer to the light..." | Read more » over 6 years ago
stoft "@viechdokter:, thanks; just a lot of years of practice. Not to worry, your's are logical and thoughtfully organized. Jeff, thanks. Yes, new observ..." | Read more » over 6 years ago
viechdokter "Hi stoft, I am really impressed by your organised experiment design and statistics approach.Compared with your's my tests are kindergarten stuff......" | Read more » over 6 years ago
warren "Ah, I also want to connect this to yesterday's post by @viechdokter: https://publiclab.org/notes/viechdokter/04-13-2016/reproducibility-test-of-dat..." | Read more » over 6 years ago
warren "Super note, Dave! It answers and raises questions: "the camera is not providing fixed exposure control" -- we'd expected this, and anticipated th..." | Read more » over 6 years ago
stoft "Great! Yes, little glitches do creep in but yes, this Solux corrected plot has a much better shape. I'm guessing the slight curve variation between..." | Read more » over 6 years ago
warren "OK, a bunch of solved problems! figured out the height difference -- needs to be resolved, but I believe due to a bug, we were multiplying each p..." | Read more » over 6 years ago