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在Python或MATLAB中从等高线图中提取数据

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我有一个这样的等高线图:

a sample contour plot

现在, if I do not have the data to generate the contour plot and all I have is the image, 如何从图像中提取每个像素的值并将其存储在数组中?

MATLAB / Python中的任何建议或示例都会有所帮助!

2 回答

  • 0

    如果你知道像素值,使用find,你可以找到你想要的位置 .

    I = imread('y5dZ1.png');
    I1 = rgb2gray(I) ;
    %%
    pix = [48 : 10 : 200] ;
    [y,x] = find(I1==200) ;
    
    imshow(I)
    hold on
    plot(x,y,'.r')
    
  • 0

    这是一个小型的Matlab脚本,可以完成这项工作(使用一些GUI,在图的斜角处读取guidlines):

    %// Import the data:
    imdata = importdata('your_picture_file');
    Gray = rgb2gray(imdata.cdata);
    colorLim = [-1 1]; %// this should be set manually
    %// Get the area of the data:
    f = figure('Position',get(0,'ScreenSize'));
    imshow(imdata.cdata,'Parent',axes('Parent',f),'InitialMagnification','fit');
    %// Get the area of the data:
    title('Click with the cross on the most top left area of the *data*')
    da_tp_lft = round(getPosition(impoint));
    title('Click with the cross on the most bottom right area of the *data*') 
    da_btm_rgt = round(getPosition(impoint));
    dat_area = double(Gray(da_tp_lft(2):da_btm_rgt(2),da_tp_lft(1):da_btm_rgt(1)));
    %// Get the area of the colorbar:
    title('Click with the cross within the upper most color of the *colorbar*')
    ca_tp_lft = round(getPosition(impoint));
    title('Click with the cross within the bottom most color of the *colorbar*')
    ca_btm_rgt = round(getPosition(impoint));
    cmap_area = double(Gray(ca_tp_lft(2):ca_btm_rgt(2),ca_tp_lft(1):ca_btm_rgt(1)));
    close(f)
    %// Convert the colormap to data:
    data = dat_area./max(cmap_area(:)).*range(colorLim)-abs(min(colorLim));
    

    现在, data 就是你要找的 .

    以下是使用问题中的图形输出的说明:

    enter image description here

    插图的代码:

    figure('Position',[100 200 1200 400]);
    subplot 121
    imshow(imdata.cdata)
    hold on
    plot(da_tp_lft(1),da_tp_lft(2),'m+','MarkerSize',7,'LineWidth',2)
    plot(da_btm_rgt(1),da_btm_rgt(2),'m+','MarkerSize',7,'LineWidth',2)
    plot(ca_tp_lft(1),ca_tp_lft(2),'r+','MarkerSize',7,'LineWidth',2)
    plot(ca_btm_rgt(1),ca_btm_rgt(2),'r+','MarkerSize',7,'LineWidth',2)
    hold off
    title('The original image')
    
    subplot 122
    surf(data)
    shading interp
    view(50,40)
    colorbar
    caxis([-1 1])
    title('Illusration of the data')
    axis tight
    

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