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Comments

Author Comment Last activity Moderation
nedhorning "My guess is that you would get the same effect that you get with a blue card if you used a gray card and then multiply the blue channel by a factor..." | Read more » about 8 years ago
nedhorning "This white balance stuff got me thinking. I don't think the white balance actually changes the amount of light recorded by the sensor but instead m..." | Read more » about 8 years ago
nedhorning "With the Infrablue filter there is both visible and NIR light hitting the camera sensor and it would be helpful to know how different wavelengths a..." | Read more » about 8 years ago
nedhorning "Sorry for not explaining this better. We were just trying to understand which sensor channels are recording which wavelengths of light. The images ..." | Read more » about 8 years ago
nedhorning "Thanks for posting this Jeff. The results are interesting. Most of the LEDs that I've seen have band widths in the 5nm - 10nm range. It's important..." | Read more » about 8 years ago
nedhorning "Would the result improve if you set white balance using a neutral target? Concrete is pretty even across the visible and near IR. " | Read more » about 8 years ago
nedhorning "Well done. I've been working a bit with texture to add additional image layers (predictor variables) to the stack for eventual automated classifica..." | Read more » about 8 years ago
nedhorning "Hi Charlie, The better we can represent the variability of the feature we are trying to classify the more accurate the result should be. In genera..." | Read more » about 8 years ago
nedhorning "HI all, I thought I made a comment on this earlier today but apparently I did something wrong (again). It's great to see more people digging into ..." | Read more » about 8 years ago
nedhorning "This isn't actually a classification. I was generating different layers from the 4-band (red, green, blue, near-IR) images collected a few weeks ag..." | Read more » about 8 years ago
nedhorning "I use those little tripods for my pole and quadcopter too. Very handy. For my kite pendulum I take off the legs and attach the ball-joint clamp thi..." | Read more » about 8 years ago
nedhorning "I have a feeling it is a white balance problem. The blue channel seems to be off. I would expect vegetation to be much darker in the blue channel. ..." | Read more » over 8 years ago
nedhorning "Is there any interest in a video processing option in the ImageJ/Fiji plugin? " | Read more » over 8 years ago
nedhorning "Increasing dynamic range will go a long way in improving NDVI results in the shadows. There are some high-dynamic-range image processing methods th..." | Read more » over 8 years ago
nedhorning "Great shots. The impact of shadows on NDVI will vary with the darkness of the shadow. Lower pixel values (darker shadow) will be more likely to pro..." | Read more » over 8 years ago
nedhorning "Hi John, It's great to see you posting on this forum. Your experience and enthusiasm are much appreciated. Thanks also for the treasure trove of r..." | Read more » over 8 years ago
nedhorning "Hi - There used to be a "Downloads" link but I just checked and couldn't find it. I only had the source files in the Git repository. To get around..." | Read more » almost 9 years ago
nedhorning "Hi Babu, As I was writing this I see you got some good comments - here are some more. Lots of good questions. I'm also looking for answers to som..." | Read more » almost 9 years ago
nedhorning "Hi Babu, As I was writing this I see you got some good comments - here are some more. Lots of good questions. I'm also looking for answers to som..." | Read more » almost 9 years ago
nedhorning "I agree a forest is not a good calibration site. For aerial and satellite sensors a popular calibration site is White Sands in New Mexico. It has w..." | Read more » almost 9 years ago
nedhorning "Another possibility for a forests area is Hubbard Brook Experimental Forest in New Hampshire but that might be a nightmare getting permission unles..." | Read more » almost 9 years ago
nedhorning "Chris - If you are referring to JPEG images acquired using one of the camera's internal white balance settings then I don't think the histograms fo..." | Read more » almost 9 years ago
nedhorning "What you describe seems like white balancing which I think of as more of a normalization process than calibration. White balance using a standard t..." | Read more » almost 9 years ago
nedhorning "Jeff - I think a good way to get a handle on this is to apply a white balance before imaging. Again, assuming that the target you use for white bal..." | Read more » almost 9 years ago