in this paper, we present an edge detection method based on wavelet transform and hessian matrix of image at each pixel. many methods which based on wavelet transform, use wavelet transform to approximate the gradient of image and detect edges by searching the modulus maximum of gradient vectors. in our scheme, we use wavelet transform to approximate hessian matrix of image at each pixel, too. ...

To improve accuracy in calculating QCD effects, we propose a method for renormalon subtraction the context of operator-product expansion. The enables subtracting renormalons various powers $\Lambda_{\rm QCD}$ efficiently and simultaneously from single-scale observables. We apply it to different observables examine consistency with theoretical expectations.