I think ImageJ could help you. You can also find on websites how to create your own script based on what you need to analyze all your pictures under the same settings.
Hi you can find different software for plant image analysis here: https://www.quantitative-plant.org/software. You can filter by plant organ, type of mesaurement, etc.
Thank you Ignacio Sevillano Eloy Navarro-León Abdelkader Mohamed Abdelkader Elsayed Laura Medina-Puche for your helpful answers and suggested tools in order to analyze my root system 2D pictures.
Plant roots are of different forms and dimensions. The analytic tools must be selected based on the species of interest. So I agree with Ignacio Sevillano's option.
ImageJ will help.But how accurately is the question. A tabletop root scanner can do the job better. Plus, you can get a host of other readings/data on the roots.