Abstract: The inaccuracy of the existing sobel edge detection operator in extraction of plant veins was analyzed. For lack of treatment effect on veins in the trunk and some small veins， a new improved algorithm was proposed. Combining with the total variation （TV） denoising model， this algorithm method dealt with the denoising of leaves. Then， based on the multi direction characteristics of vein trend， in two or four directions of existing template， the other direction template was considered， a new one containing eight direction template operator was constructed. And this template operator was used for veins extraction of plant leaves. Experimental results showed that compared with the traditional algorithm， the proposed algorithm can not only remove the noise effectively， but also keep the detail information of vein trunk， which can fully extract the trunk and small veins.

Key words: sobel edge detection, eight\, direction template, TV denoising