foreign open the image of Interest using image J in this tutorial video the percentage area of the disease leaf will be measured we will measure all the disease areas in this Leaf to set the scale bar select the line tool from above and draw a straight line parallel to one centimeter in the ruler then head to analyze set scale input the known distance as 1. and the unit of length as centimeter check on global to analyze more than one image once completed click OK it is important to remove the line that was used to set the scale bar the ruler from the image can be removed if required select the rectangular selection tool from above and mark the reason of Interest then head to image and crop now this image excludes the ruler to measure the total area of the leaf click on image adjust and color threshold in the color threshold window adjust the Hue such that the entire leaf is red in color once the threshold is set click on select this window can be closed now click on process binary and make binary set the parameters to measure the area of the threshold regions only to do this click on analyze and set measurements in the set measurements window select the area and limit to threshold once completed click ok to measure the threshold area click on analyze and measure the results window shows the total area of the leaf to be 42. 236 centimeter Square this image can be saved if required to measure the area of the disease leaf open the image again using image J crop the image again if the ruler is to be excluded now adjust the color threshold again like before drag and change the Hue saturation or brightness in such a way that only the disease area is under threshold [Music] once completed click on select change the image into binary by clicking on process binary and make binary during the threshold there are areas under threshold that may not have reflected the disease leave these are called noise that needs to be removed before analyzing the area to remove noise click on process noise and remove outliers in the remove outlier window change the radius to 5 pixels and set the threshold to 50 from the drop down select the dark outlier check on the preview to visualize in real time if noise has been eliminated if the noise are still visible increase the radius for instance 7 pixels once noise have been removed measure the area of the threshold reason click on analyze and measure in the results window the area of the disease leaf is found to be 1.
49 centimeter Square this image can be saved in any format of your choice if required to calculate the percentage area of the disease leaf use the following formula this is leaf area over total lift area multiplied by 100 that is 1. 49 over 42. 236 multiplied by 100 that is equal to 3.
