Automatic counting of annual rings on Pinus sylvestris end faces in sawmill industry

The quality of wood can be analyzed using annual ring width. At Swedish sawmills, this is performed using manual inspection for grading purpose. Here a completely automatic method for counting the number of annual rings on log end faces is described and evaluated. The method is applied and tested using images from Pinus sylvestris end faces acquired in online sawmill production with a camera mounted above a conveyor belt. Completely untreated end faces were captured, as well as newly sawn ones. The proposed method includes preprocessing, pith detection and counting the number of rings in two regions of the end face. A new method to remove marks from uneven sawing is presented as a part of the preprocessing steps. The evaluation shows that the suggested automatic method performs as well as the manual measurements that are the method used for measuring today.

Research Highlights▶ An automatic method for counting the number of annual rings on log end face images. ▶ Data are acquired in online sawmill production at a conveyor belt. ▶ An evaluation shows that the automatic method performs as well as a manual grader.