Comments

Author Comment Last activity Moderation
nedhorning " I can think of two possible reason. The most obvious would be that the illumination changed and the other is that the sensor temperature change. S..." | Read more » almost 4 years ago
nedhorning "It's good you discovered that. Yesterday I started to write about the need to subtract the blue band (NIR) from the red band (red + NIR) so you get..." | Read more » almost 4 years ago
nedhorning "I used this following dcraw command: dcraw -D -W -4 Image1.ORF to create this image which has been scaled to 16-bit integers: https://drive.googl..." | Read more » almost 4 years ago
nedhorning " I have to run out now but will try to make time to check this in the morning. It's also possible it's due to the nature of the filter and after ca..." | Read more » almost 4 years ago
nedhorning "Can you post one of your RAW images? I looked at Image1.dng and that shows the Bayer pattern so it needs to go through a debayer process to create ..." | Read more » almost 4 years ago
nedhorning "I use RAW pixel values for calibration analysis and since white balance doesn't impact RAW values I don't usually worry about it. If you want to us..." | Read more » almost 4 years ago
nedhorning "The calibration coefficients are, in the simplest case, the slope and y-intercept of the linear regression line for wavelength (based on calibratio..." | Read more » almost 4 years ago
nedhorning " If you're using them for calibration you should be fine taking photos of the targets every so often. The calibration coefficients shouldn't change..." | Read more » almost 4 years ago
nedhorning "I just read over Rob Sumner's RAW guide and see Adobe DNG Converter is free. It also looks like he did some pretty rigorous tests so my previous co..." | Read more » almost 4 years ago
nedhorning "The tables look great. Before the end of the week I'll try to compare your converted image with on that I run through dcraw to see if they are simi..." | Read more » almost 4 years ago
nedhorning " Hi Corymbia – It’s nice to see some new work in this area. I see that you used the Adobe DNG converter. You might want to look into that to under..." | Read more » almost 4 years ago
nedhorning "For the most part I am not able to reliably and accurately validate NDVI calculations. To validate results you would need to have targets with know..." | Read more » almost 5 years ago
nedhorning "Hi Suman - Using Analyze => Measure should work. It's not uncommon to have high pixel values for bright targets. In fact if the exposure isn't s..." | Read more » over 5 years ago
nedhorning "Hi Suman - The values from 0 - 1 have been scaled from the original image. The reason I do this is that some image pixel values range from 0 - 255 ..." | Read more » over 5 years ago
nedhorning "The CSV file for the R script is different form the table in the "Improved DIY NIR camera calibration" post. The CSV file has the reflectance value..." | Read more » almost 6 years ago
nedhorning "Hi - Using 440nm seem reasonable but I'd probably increase the NIR value to 760nm or beyond or something like that since the peak is probably beyon..." | Read more » over 6 years ago
nedhorning "Hi David - This is an interesting project. The reflection of the glass should affect the results as long as the reflection is not in the area of yo..." | Read more » over 6 years ago
nedhorning "The current version of the plugin only outputs index (NDVI and DVI) images. The plugin only calibrates two bands, a visible and a NIR band and two ..." | Read more » about 7 years ago
nedhorning "Hi Jacob, To check for aperture you could try another EXIF reader. Maybe "max aperture" is the same as "aperture" but I have no idea. When working ..." | Read more » about 7 years ago
nedhorning "I haven't seen reflectance curves for the "standard" white balance cards that include the NIR region of the spectrum. My guess is they would differ..." | Read more » about 7 years ago
nedhorning "Unfortunately those values would only work if you had the same materials that I used. To get the reflectance values you would either need to fine s..." | Read more » over 7 years ago
nedhorning "Hi aldehyde - Did you look at the user guide on Github: https://github.com/nedhorning/PhotoMonitoringPlugin that should have information about crea..." | Read more » over 7 years ago
nedhorning "Mathew - Have you been able to find a reflectance plot for those paints? I looked but didn't see it. Other paints I was looking at a couple years a..." | Read more » over 7 years ago
nedhorning "HI Agustin - I put the images on my server here: https://resources.cbc.amnh.org/cbccloudstorage/public.php?service=files&t=12385a3a09a4879fcffc..." | Read more » over 7 years ago