I have 3 images of plant germination and each image is of different dimensions. I resized all of them using paint to 600 (width) X 450 (length) pixels. But the scale size in the 3 images is of different length. I drew 4 cm scale by image j in all 3 images but their length is varying on all of them. So, How should equalize scale lengths in the all 3 images, so that its easy to compare shoot length among them ?
if you want to measure the shoot length in imageJ, you do not need to resize the images before. Just tell ImageJ the dimension of the pixels for each image by drawing a line over your scale bar and setting the scale to 4 cm.
If you then measure the shoot length using the line tool again, your measurements will be adjusted to cm.