ImageJ Tutorial 1.4 - Measure Leaf Disease Area (Sampled Leaves)
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- เผยแพร่เมื่อ 27 พ.ค. 2024
- This is the first in our lab's series of ImageJ Tutorials! This tutorial is all about measurements on diseased leaves!
In this video we learn how to measure leaf disease area for sampled leaves!
- 0:25 - Capture total leaf area
- 4:10 - Capture diseased leaf area
- 6:57 - Calculate the % disease damage
Merci pour l’information
Wonderful !
Thank you for the comment! Glad you like it!
Nice tutorial
Thank you for the comment!
Hello and thanks for the video! Very useful for other plants such as Lemna minor! I found out that the selection made during Colour threshold is lost after "Make binary". Although the selected area can be restored by "Restore selection", this is problematic because it selects everything before the cleanup, so it really doesnt help to select only the leaf areas, as usually the color threshold select other areas as well. Any ideas? Thanks again!
It is like it does not select the threshold, rather the whole image when it measures the area...
@@vikmnilu We are very glad you found the video useful! What our lab has found is that after the cleanup, sometimes the image has dropped the binary setting. In order to restore it, all you have to do is select Process > Binary > Make Binary again after the cleanup, and it should select the black pixels for the measurement.
If that still doesn't fix the problem, it may be your Control+M is measuring the wrong measurements. To correct that, go to "Analyze > Set Measurements" and to make sure to select "Area" and "Limit to threshold." Control+M will measure the area of the entire image or the area of your current selection if "Limit to threshold" is not selected.
Hi! Thank you for this tutorial. I tried several times, but when converting into binary I found my area of interest colored white instead of black. Is there a possibility to invert the colors? What step am I missing? Thanks in advance :)
Hello, Laura! Absolutely, we've run into that issue with ImageJ too. ImageJ shouldn't do this, but it does.
You can invert the image by going to "Edit > Invert," and that will color the area of interest black instead of white. It may be that when you do that and measure the area, it will provide the total area of the image instead of the black pixel area. Converting the image to binary again will result in a measurable black area. However, converting the image to binary may also invert the image again.
One simple workaround is to go ahead and measure the inverted area, invert the image, measure the total area, and minus the inverted area from the total area. That will result in a good looking binary image, and it will also provide the area of the area of interest.
very much helpful for me. i just want to know either by this we can estimate leaf damage by insect feeding or not..?
Hello, Shehzad! We are delighted you enjoyed the video! I think it would be possible to estimate leaf damage by insect feeding. What you would have to do is determine some characteristics of the lesions caused by the insect in question (color, shape) which can distinguish the lesions from other marks on the leaf, and then the information you want about the damage.
You could count the number of lesions:
For a leaf scan: th-cam.com/video/YV5L_YDMkRo/w-d-xo.html
For a field image: th-cam.com/video/bDuj4Jl1OS8/w-d-xo.html
You could measure the area of the leaf damaged (process similar to this video).
We may produce more videos about insect damage at some point as well. What insect feeding damage are you interested in specifically?