diff --git a/skimage/feature/censure.py b/skimage/feature/censure.py index 2dda9306..199cfbaa 100644 --- a/skimage/feature/censure.py +++ b/skimage/feature/censure.py @@ -11,25 +11,27 @@ from skimage.feature.censure_cy import _censure_dob_loop OCTAGON_OUTER_SHAPE = [(5, 2), (5, 3), (7, 3), (9, 4), (9, 7), (13, 7), - (15, 10)] -OCTAGON_INNER_SHAPE = [(3, 0), (3, 1), (3, 2), (5, 2), (5, 3), (5, 4), (5, 5)] + (15, 10), (15, 11), (15, 12), (17, 13), (17, 14)] +OCTAGON_INNER_SHAPE = [(3, 0), (3, 1), (3, 2), (5, 2), (5, 3), (5, 4), (5, 5), + (7, 5), (7, 6), (9, 6), (9, 7)] STAR_SHAPE = [1, 2, 3, 4, 6, 8, 11, 12, 16, 22, 23, 32, 45, 46, 64, 90, 128] STAR_FILTER_SHAPE = [(1, 0), (3, 1), (4, 2), (5, 3), (7, 4), (8, 5), (9, 6), (11, 8), (13, 10), (14, 11), (15, 12), (16, 14)] -def _filter_image(image, min_scale, max_scale, mode): +def _get_filtered_image(image, min_scale, max_scale, mode): - response = np.zeros((image.shape[0], image.shape[1], - max_scale - min_scale + 1), dtype=np.double) + scales = np.zeros((image.shape[0], image.shape[1], + max_scale - min_scale + 1), dtype=np.double) if mode == 'dob': - # make response[:, :, i] contiguous memory block - item_size = response.itemsize - response.strides = (item_size * response.shape[0], item_size, - item_size * response.shape[0] * response.shape[1]) + # make scales[:, :, i] contiguous memory block + item_size = scales.itemsize + scales.strides = (item_size * scales.shape[0], + item_size, + item_size * scales.shape[0] * scales.shape[1]) integral_img = integral_image(image) @@ -37,12 +39,12 @@ def _filter_image(image, min_scale, max_scale, mode): n = min_scale + i # Constant multipliers for the outer region and the inner region - # of the bi-level filters with the constraint of keeping the + # of the bilevel filters with the constraint of keeping the # DC bias 0. inner_weight = (1.0 / (2 * n + 1)**2) outer_weight = (1.0 / (12 * n**2 + 4 * n)) - _censure_dob_loop(n, integral_img, response[:, :, i], + _censure_dob_loop(n, integral_img, scales[:, :, i], inner_weight, outer_weight) # NOTE : For the Octagon shaped filter, we implemented and evaluated the @@ -56,17 +58,17 @@ def _filter_image(image, min_scale, max_scale, mode): for i in range(max_scale - min_scale + 1): mo, no = OCTAGON_OUTER_SHAPE[min_scale + i - 1] mi, ni = OCTAGON_INNER_SHAPE[min_scale + i - 1] - response[:, :, i] = convolve(image, - _octagon_filter_kernel(mo, no, mi, ni)) - + scales[:, :, i] = convolve(image, + _octagon_filter_kernel(mo, no, mi, ni)) elif mode == 'star': for i in range(max_scale - min_scale + 1): m = STAR_SHAPE[STAR_FILTER_SHAPE[min_scale + i - 1][0]] n = STAR_SHAPE[STAR_FILTER_SHAPE[min_scale + i - 1][1]] - response[:, :, i] = convolve(image, _star_filter_kernel(m, n)) + scales[:, :, i] = convolve(image, + _star_filter_kernel(m, n)) - return response + return scales # TODO : Import from selem after getting #669 merged. @@ -137,24 +139,24 @@ def _suppress_lines(feature_mask, image, sigma, line_threshold): def keypoints_censure(image, min_scale=1, max_scale=7, mode='DoB', non_max_threshold=0.15, line_threshold=10): """ - Extracts CenSurE keypoints along with the corresponding scale using - either Difference of Boxes, Octagon or STAR bi-level filter. + Extracts Censure keypoints along with the corresponding scale using + either Difference of Boxes, Octagon or STAR bilevel filter. Parameters ---------- image : 2D ndarray Input image. - min_scale : int + min_scale : positive integer Minimum scale to extract keypoints from. - max_scale : int + max_scale : positive integer Maximum scale to extract keypoints from. The keypoints will be extracted from all the scales except the first and the last i.e. from the scales in the range [min_scale + 1, max_scale - 1]. - mode : {'DoB', 'Octagon', 'STAR'} - Type of bi-level filter used to get the scales of the input image. + mode : ('DoB', 'Octagon', 'STAR') + Type of bilevel filter used to get the scales of the input image. Possible values are 'DoB', 'Octagon' and 'STAR'. The three modes - represent the shape of the bi-level filters i.e. box(square), octagon - and star respectively. For instance, a bi-level octagon filter consists + represent the shape of the bilevel filters i.e. box(square), octagon + and star respectively. For instance, a bilevel octagon filter consists of a smaller inner octagon and a larger outer octagon with the filter weights being uniformly negative in both the inner octagon while uniformly positive in the difference region. Use STAR and Octagon for @@ -169,7 +171,7 @@ def keypoints_censure(image, min_scale=1, max_scale=7, mode='DoB', Returns ------- keypoints : (N, 2) array - Location of the extracted keypoints in the ``(row, col)`` format. + Location of the extracted keypoints in the (row, col) format. scales : (N, 1) array The corresponding scale of the N extracted keypoints. @@ -186,9 +188,8 @@ def keypoints_censure(image, min_scale=1, max_scale=7, mode='DoB', http://www.jamris.org/01_2013/saveas.php?QUEST=JAMRIS_No01_2013_P_11-20.pdf """ - # (1) First we generate the required scales on the input grayscale image - # using a bi-level filter and stack them up in `filter_response`. + # using a bilevel filter and stack them up in `filter_response`. # (2) We then perform Non-Maximal suppression in 3 x 3 x 3 window on the # filter_response to suppress points that are neither minima or maxima in # 3 x 3 x 3 neighbourhood. We obtain a boolean ndarray `feature_mask` @@ -207,15 +208,15 @@ def keypoints_censure(image, min_scale=1, max_scale=7, mode='DoB', if mode not in ('dob', 'octagon', 'star'): raise ValueError('Mode must be one of "DoB", "Octagon", "STAR".') - if min_scale < 1 or max_scale < 1 or max_scale - min_scale < 2: - raise ValueError('The scales must be >= 1 and the number of scales ' - 'should be >= 3.') + if max_scale - min_scale < 2: + raise ValueError('The number of scales should be greater than or' + 'equal to 3.') image = img_as_float(image) image = np.ascontiguousarray(image) # Generating all the scales - filter_response = _filter_image(image, min_scale, max_scale, mode) + filter_response = _get_filtered_image(image, min_scale, max_scale, mode) # Suppressing points that are neither minima or maxima in their 3 x 3 x 3 # neighbourhood to zero