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 "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, 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 » almost 6 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
nedhorning "Hi Jeff - This should be the image. Let me know if this is ok or if I need to post it some other way Ned " | Read more » about 6 years ago
nedhorning "Hi kaushalsingh – The three target reflectance values you note seem like a good choice to me. At this point I do not have study material in additi..." | Read more » about 6 years ago
nedhorning "Hi kaushalsingh – Ait seems as if you are trying to calibrate the image using a reference target before you calculate NDVI? If that assumption is a..." | Read more » about 6 years ago
nedhorning "Several years ago I was thinking of how to build a DIY integrating sphere/monochromator setup but never pursued it. You would want something other ..." | Read more » about 7 years ago
nedhorning "The image for this note with the blue color was probably a JPEG image white balanced using red paper. The raw image will have much higher values in..." | Read more » over 7 years ago
nedhorning "Hi Agustin - I have a feeling the problem with with the calibration targets you are using. The targets I sued for this note were scanned by a labor..." | Read more » over 7 years ago