diff --git a/skimage/filter/_denoise_cy.pyx b/skimage/filter/_denoise_cy.pyx index 6fd95f03..6e803062 100644 --- a/skimage/filter/_denoise_cy.pyx +++ b/skimage/filter/_denoise_cy.pyx @@ -200,7 +200,7 @@ def denoise_bilateral(image, Py_ssize_t win_size=5, sigma_range=None, return np.squeeze(out) -def denoise_tv_bregman(image, double weight, int max_iter=100, double eps=1e-3): +def denoise_tv_bregman(image, double weight, int max_iter=100, double eps=1e-3, anisotropic=False): """Perform total-variation denoising using split-Bregman optimization. Total-variation denoising (also know as total-variation regularization) @@ -225,6 +225,8 @@ def denoise_tv_bregman(image, double weight, int max_iter=100, double eps=1e-3): max_iter: int, optional Maximal number of iterations used for the optimization. + anisotropic: boolean, optimal - switch between isotropic and anisotropic tv denoising + Returns ------- u : ndarray @@ -239,6 +241,7 @@ def denoise_tv_bregman(image, double weight, int max_iter=100, double eps=1e-3): .. [3] Pascal Getreuer, "Rudin–Osher–Fatemi Total Variation Denoising using Split Bregman" in Image Processing On Line on 2012–05–19, http://www.ipol.im/pub/art/2012/g-tvd/article_lr.pdf + [4] http://www.math.ucsb.edu/~cgarcia/UGProjects/BregmanAlgorithms_JacquelineBush.pdf """ @@ -325,9 +328,26 @@ def denoise_tv_bregman(image, double weight, int max_iter=100, double eps=1e-3): bxx = bx[r, c, k] byy = by[r, c, k] - s = sqrt((ux + bxx)**2 + (uy + byy)**2) - dxx = s * lam * (ux + bxx) / (s * lam + 1) - dyy = s * lam * (uy + byy) / (s * lam + 1) + # d_subproblem after reference [4] + if anisotropic: + s = ux + bxx + if s > 1/lam: + dxx = s - 1/lam + elif s < -1/lam: + dxx = s + 1/lam + else: + dxx = 0 + s = uy + byy + if s > 1/lam: + dyy = s - 1/lam + elif s < -1/lam: + dyy = s + 1/lam + else: + dyy = 0 + else: + s = sqrt((ux + bxx)**2 + (uy + byy)**2) + dxx = s * lam * (ux + bxx) / (s * lam + 1) + dyy = s * lam * (uy + byy) / (s * lam + 1) dx[r, c, k] = dxx dy[r, c, k] = dyy