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| -rw-r--r-- | python/force_field_transform.py | 126 |
1 files changed, 0 insertions, 126 deletions
diff --git a/python/force_field_transform.py b/python/force_field_transform.py deleted file mode 100644 index 2b185c8..0000000 --- a/python/force_field_transform.py +++ /dev/null @@ -1,126 +0,0 @@ -# -*- coding: utf -*- -# -# Force field transform (Hurley et al., 2002, 2005) -# - -""" -Force field transform -""" - -import sys -import time -import numpy as np - - -def force(p1, p2): - """ - The force between two points of the image. - - Arguments: - p1, p2: (value, x, y) - - Return: - # (force, angle): value and direction of the force. - # angle: (-pi, pi], with respect to p1. - (f_x, f_y): x and y components of the force - """ - v1, x1, y1 = p1 - v2, x2, y2 = p2 - #force = v1*v2 / ((x1-x2)**2 + (y1-y2)**2) - #angle = np.atan2(y2-y1, x2-x1) - #return (force, angle) - f_x = v1 * v2 * (x2-x1) / ((x2-x1)**2 + (y2-y1)**2)**1.5 - f_y = v1 * v2 * (y2-y1) / ((x2-x1)**2 + (y2-y1)**2)**1.5 - return (f_x, f_y) - - -def force_array(p0, img): - """ - The forces between the input point with respect to the image. - - Arguments: - p0: (x, y), note (x, y) start with zero. - img: input image, a numpy array - - Return: - (f_x, f_y): x and y components of the forces of the same size - of the input image - """ - x0, y0 = p0 - v0 = img[y0, x0] - img[y0, x0] = 0.0 - x, y = np.meshgrid(range(img.shape[1]), range(img.shape[0])) - x[y0, x0] = -1 - y[y0, x0] = -1 - f_x = v0 * img * (x-x0) / ((x-x0)**2 + (y-y0)**2)**1.5 - f_y = v0 * img * (y-y0) / ((x-x0)**2 + (y-y0)**2)**1.5 - return (f_x, f_y) - - -def vector_add(v1, v2): - """ - Add two vectors and return the results. - - Arguments: - v1, v2: two input vectors of format (f_x, f_y) - - Return: - (F_x, F_y) - """ - f1_x, f1_y = v1 - f2_x, f2_y = v2 - return (f1_x+f2_x, f1_y+f2_y) - - -def force_summation(pixel, img): - """ - Calculate the resulting force of the specified pixel with respect to - the image. - - Argument: - pixel: the position (x, y) of the pixel to be calculated - img: the input image - - Return: - (F_x, F_y): x and y components of the resulting force. - """ - img = np.array(img) - x0, y0 = pixel - f_x, f_y = force_array((x0, y0), img) - return (f_x.sum(), f_y.sum()) - - -def force_field_transform(img): - """ - Perform the "force field transform" on the input image. - - Arguments: - img: input 2D image - - Return: - (amplitudes, angles) - amplitudes: the amplitudes of the resulting forces of each pixel - angles: the directions of the resulting forces of each pixel, - in unit radian. - """ - img = np.array(img) - amplitudes = np.zeros(img.shape) - angles = np.zeros(img.shape) - rows, cols = img.shape - t0 = time.time() - t_p = t0 + 30 # in 30 seconds - for y in range(rows): - for x in range(cols): - t1 = time.time() - if t1 >= t_p: - percent = 100 * (y*cols + x + 1) / (rows * cols) - print("progress: %.3f%%; %.1f min" % (percent, (t1-t0)/60.0), - file=sys.stderr) - t_p += 30 # in 30 seconds - f_x, f_y = force_array((x, y), img) - F_x, F_y = f_x.sum(), f_y.sum() - amplitudes[y, x] = np.sqrt(F_x**2 + F_y**2) - angles[y, x] = np.math.atan2(F_y, F_x) - return (amplitudes, angles) - - |