Python实现PS滤镜特效之扇形变换效果示例_Python

本文实例讲述了Python实现PS滤镜特效之扇形变换效果。分享给大家供大家参考，具体如下：

这里用 Python 实现 PS 滤镜中的一种几何变换特效，称为扇形变换，将图像扭曲成一个扇形，具体的算法原理和效果图可以参考附录说明

									import numpy as np

									from skimage import img_as_float

									import matplotlib.pyplot as plt

									from skimage import io

									import math

									import numpy.matlib

									file_name2='D:/Visual Effects/PS Algorithm/4.jpg'

									img=io.imread(file_name2)

									img = img_as_float(img)

									# control the radius of the inner circle

									radius = 150

									# control the distance between the inner circle and outer circle

									high = 200

									angle = 0

									spreadAngle = math.pi

									# set the center of the circle, proportion of the image size

									centerX = 0.5

									centerY = 1.0

									row, col, channel = img.shape

									icenterX = col * centerX

									icenterY = row * centerY

									img_out = img * 0

									xx = np.arange (col)

									yy = np.arange (row)

									x_mask = numpy.matlib.repmat (xx, row, 1)

									y_mask = numpy.matlib.repmat (yy, col, 1)

									y_mask = np.transpose(y_mask)

									xx_dif = x_mask - icenterX

									yy_dif = y_mask - icenterY

									theta = np.arctan2(-yy_dif, -xx_dif+0.0001)

									r = np.sqrt(xx_dif*xx_dif + yy_dif * yy_dif)

									theta = np.mod(theta, 2 * math.pi)

									x1_mask = col * theta/(spreadAngle+0.00001)

									y1_mask = row * (1-(r-radius)/(high+0.00001))

									'''

									mask = x1_mask < 0

									x1_mask = x1_mask * (1 - mask)

									mask = x1_mask > (col - 1)

									x1_mask = x1_mask * (1 - mask) + (x1_mask * 0 + col -2) * mask

									mask = y1_mask < 0

									y1_mask = y1_mask * (1 - mask)

									mask = y1_mask > (row -1)

									y1_mask = y1_mask * (1 - mask) + (y1_mask * 0 + row -2) * mask

									'''

									int_x = np.floor (x1_mask)

									int_x = int_x.astype(int)

									int_y = np.floor (y1_mask)

									int_y = int_y.astype(int)

									for ii in range(row):

									  for jj in range (col):

									    new_xx = int_x [ii, jj]

									    new_yy = int_y [ii, jj]

									    if x1_mask [ii, jj] < 0 or x1_mask [ii, jj] > col -1 :

									      continue

									    if y1_mask [ii, jj] < 0 or y1_mask [ii, jj] > row -1 :

									      continue

									    img_out[ii, jj, :] = img[new_yy, new_xx, :]

									plt.figure (1)

									plt.title('www.zyiz.net')

									plt.imshow (img)

									plt.axis('off')

									plt.figure (2)

									plt.title('www.zyiz.net')

									plt.imshow (img_out)

									plt.axis('off')

									plt.show()

附录：PS 滤镜— —扇形warp

									clc;

									clear all;

									close all;

									addpath('E:\PhotoShop Algortihm\Image Processing\PS Algorithm');

									I=imread('4.jpg');

									I=double(I);

									Image=I/255;

									[height, width, depth]=size(Image);

									% set the parameters

									radius = 150; % control the radius of the inner circle

									high = 200;  % control the distance between the inner circle and outer circle

									angle = 0;       

									spreadAngle=pi;  

									centerX = 0.5; % set the center of the circle, proportion of the image size

									centerY = 1.0;

									icenterX=width*centerX;

									icenterY=height*centerY;

									Image_new=Image*0;

									for i=1:height

									  for j=1:width

									    dx=j-icenterX;

									    dy=i-icenterY;

									    theta=atan2(-dy, -dx)+angle;

									    r=sqrt(dy*dy+dx*dx);

									    theta=mod(theta, 2*pi);

									    x=width * theta/(spreadAngle+0.00001);

									    y=height * (1-(r-radius)/(high+0.00001));

									% %     if (x<=1)   x=1; end

									% %     if (x>=width)  x=width-1; end;

									% %     if (y>=height) y=height-1; end;

									% %     if (y<1) y=1;   end;

									% %    

									    if (x<=1)   continue; end

									    if (x>=width)  continue; end;

									    if (y>=height) continue; end;

									    if (y<1) continue;   end;

									    x1=floor(x);

									    y1=floor(y);

									    p=x-x1;

									    q=y-y1;

									    Image_new(i,j,:)=(1-p)*(1-q)*Image(y1,x1,:)+p*(1-q)*Image(y1,x1+1,:)...

									      +q*(1-p)*Image(y1+1,x1,:)+p*q*Image(y1+1,x1+1,:);

									  end

									end

									imshow(Image_new)

									imwrite(Image_new, 'out.jpg');