Comments

Author Comment Last activity Moderation
nedhorning "NDVI uses an NIR and a Red band. Some documents have noted that instead of red you can any visible band but from my point of view that is not corre..." | Read more » over 1 year ago
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 " Nice photos. I suggest using lighting conditions similar to those for the photos you plan to take. Once you get the white balance routine down it'..." | Read more » about 4 years ago
nedhorning "Do the images you acquire using "Auto" mode look the same or very similar to the ones you acquire using the custom white balance? " | Read more » about 4 years ago
nedhorning " Hi: It looks like you are using "Auto" mode when taking the photo. I don't have this camera but I found this web site that might help: https://sup..." | Read more » about 4 years ago
nedhorning "It's worth testing but those cards you link to look promising. From my experience it's the bright target that is more of a problem than the dark ta..." | Read more » about 4 years ago
nedhorning "Hi Jeff - I wasn't sure if you mean varying over time or over the surface. Over time both will vary but from my experience they seem fairly stable ..." | Read more » about 4 years ago
nedhorning "Setting up and running an integrating sphere is within your reach for a 12 week course as long as the equipment is working and you have access to s..." | Read more » about 5 years ago
nedhorning "Hi dannysmith - I’m glad to hear the note was useful to get you started. I find it helpful to plot both red and blue channel regressions but I expe..." | Read more » about 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 "Hi Suman, I do not have a peer reviewed manuscript about this work so suggest citing this web page using a style appropriate for websites or blogs...." | Read more » over 5 years ago
nedhorning "Hi sujayj - I uploaded files with the target descriptions and reflectance information to my Google Drive: https://drive.google.com/drive/folders/0B..." | Read more » almost 6 years ago
nedhorning "Hi jenjimah, Testing any of these and reporting back would be worthwhile from my perspective. One word of caution is that these are very bright re..." | Read more » almost 6 years ago