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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » over 10 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 » almost 11 years ago
nedhorning "Is there any interest in a video processing option in the ImageJ/Fiji plugin? " | Read more » almost 11 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 » almost 11 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 » almost 11 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 » almost 11 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 » over 11 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 » over 11 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 » over 11 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 » over 11 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 » over 11 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 » over 11 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 » over 11 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 » over 11 years ago