I need to trace the length of neuron processes after Golgi cox staining method. What will be the suitable procedure for the measurement with reference to the known scale bar in the image?
You can use the line tool to draw a line across any feature and then measure the line. This of course assumes that you are able to properly calibrate the image (pixel width & height in the properties). The area will also require this calibration. For the area it is easiest to use a greyscale image and threshold it until the area you want is masked, then open the ROI manager, use the wand tool to select the area and click add in the ROI manager. You can now use the measure function in the ROI manager to get the area of the selected ROI.