| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| warren | "That's a great thing to point out -- do you per chance have a link to the spectral bandwidth of the sensors? Thanks! " | Read more » | about 8 years ago | |||
| stef | "The BIG advantage of the Raspberry Pi is the use of the Sony IMX298 sensor whose spectral bandwidth is known and is 16 megapixel sensor. Much like ..." | Read more » | about 8 years ago | |||
| warren | "Hi, thanks for posting! One thing I've wondered about is whether different exposures -- that are not clipping/overexposed but are different overall..." | Read more » | over 8 years ago | |||
| viechdokter | "Hi Chris, you are right, the settings are important too. I absolutely forgot to mention them. Here is a (translated) snapshot of the settings: ..." | Read more » | over 8 years ago | |||
| cfastie | "Hi viechdokter, These are great observations. They reveal important features of spectra created using consumer cameras as the detector. It's real..." | Read more » | over 8 years ago | |||
| amysoyka | "Snap. We should have a brainstorming session on cheap forms of reflective stuff! My list so far has been: -Alufoil. (Too easy to crease - which lo..." | Read more » | about 10 years ago | |||
| stoft | "They look good in the pic. It is difficult to get a ideal gradients with actual dots or lines. You might try attenuating the florescence light vs l..." | Read more » | about 10 years ago | |||
| mathew | " gradient_print.pdf @stoft just got these back. The silver nitrate emulsion is line-screened at 300dpi, and goes from 100% black to 100% clear..." | Read more » | about 10 years ago | |||
| mathew | "@stoft I just sent off a group of fades on acetate to the photo printer we use for our slits. We'll try it out soon. " | Read more » | about 10 years ago | |||
| btbonval | "On the plots, it looks like you have linearly sampled x-data, around 300 nm to 700 nm. The question is whether each x-value is equally spaced. If t..." | Read more » | about 10 years ago | |||
| warren | "The interval is from pixel width on the sensor, so I think it's a safe assumption? " | Read more » | about 10 years ago | |||
| btbonval | "@warren You aren't taking integrals, you're accumulating y-values. This might be equivalent if and only if the difference between x-value samples ..." | Read more » | about 10 years ago | |||
| btbonval | "In numpy, it'd be fairly easy. # establish that x and y are 1d vectors xdata = data[0,:] ydata = data[1,:] # perform cumulative sc..." | Read more » | about 10 years ago | |||
| warren | "Hi bryan - my code is here: https://spectralworkbench.org/macro/warren/centroidish -- I wonder if you did an implementation how different the line ..." | Read more » | about 10 years ago | |||
| btbonval | "If you have access to matrix math, I can vectorize the previous algorithm to speed it up. If you're in client javascript, I'm unaware of any good v..." | Read more » | about 10 years ago | |||
| btbonval | "Here's a dirty and slow way to determine the 50% mark: Firstly, normalize your data by dividing the integral (area under the curve). The area unde..." | Read more » | about 10 years ago | |||
| stoft | "btbonval - point taken, centriod is for 2D; their line just represents the 'center of distribution' " | Read more » | about 10 years ago | |||
| stoft | "btbonval - true. I was just suggesting a fast integer approximation as a simple means to test and get a 1-number result. The existing work in patte..." | Read more » | about 10 years ago | |||
| btbonval | "@stoft the centroid would be a point (x,y), not a line (x=B for all y). sorry to nitpick verbiage. I got all mathy in this post, figured I'd keep u..." | Read more » | about 10 years ago | |||
| btbonval | "What @stoft described in the first message is usually accomplished using a matched filter in DSP. http://en.wikipedia.org/wiki/Matched_filter " | Read more » | about 10 years ago | |||
| stoft | "I think the term you are looking for is the "centroid" -- think of it as the point where the shape/volume/whatever would be physically balanced -- ..." | Read more » | about 10 years ago | |||
| btbonval | "@warren The line that you describe would be the weighted mean of the dataset (integral divided by two, aka area under the curve divided by two as @..." | Read more » | about 10 years ago | |||
| mathew | "@stevie running three samples and averaging them is a great idea. You can see in the labels that I started running 3-5 tests per sample to go for ..." | Read more » | about 10 years ago | |||
| mathew | "@stoft Dave, we're getting similar brightnesses between our readings of different oils by varying the concentration and/or light path, which seem t..." | Read more » | about 10 years ago |