如何裁剪和縮放與另一個圖像相關的圖像？

Question

我有兩個圖像：手動分割（紅線）和自動分割（藍線）。

我想要做的是

1. 重疊它們，以便在第一對應於第二點的點。
2. 裁剪圖像（自動分割）以使點具有相同的尺寸和相同的比例尺，以便我可以通過比較兩個輪廓來驗證分割。

雖然我試圖從MATHWORKS，registering-an-image-using-normalized-cross-correlation類似的解決方案，使用下面的代碼，而是我得到一個錯誤。

我在做什麼錯？爲什麼xbegin和offset爲負？

% Algorithm for image validation 
    % Open the two images which will be compared 
    name2=input('Image name (automated segmentation)  ','s'); 
    img_automated=imread(name2,'png'); 
    figure (1), imshow(img_automated), title('Image automated') 
    name=input('Image name (manual segmentation)  ','s'); 
    img_manual=imread(name,'png'); 
    img_manual_gray=rgb2gray(img_manual); 
    figure (2), imshow (img_manual),title('Image manual') 
    img_automated_gray=rgb2gray(img_automated); 
    %img_double=im2double(img_automated_gray); 
    figure (3), imshow (img_automated_gray), title (' Image converted to double '); 
    imcontrast 
    %uiwait(img_automated_gray) 
    img_automated_eq=adapthisteq(img_automated_gray); 
    figure (5), imshow (img_automated_eq), title (' Image after histogram equalization '); 
    img_automated_gray=rgb2gray(img_automated); 
    figure (6), imshowpair(img_manual,img_automated_eq) 
    title('Images overlap') 

    %Step 2: Choose Subregions of Each Image 
    %It is important to choose regions that are similar.The image sub_automated 
    %will be the template, and must be smaller than the image sub_manual. 
    % interactively 

    [sub_manual,rect_manual] = imcrop(img_manual); % choose the pepper below the onion 
    [sub_automated,rect_automated] = imcrop(img_automated_gray); % choose the whole onion 
    % display sub images 
    figure(8), imshow(sub_automated) 
    figure(9), imshow(sub_automated) 

    %Step 3: Do Normalized Cross-Correlation and Find Coordinates of Peak 
    %Calculate the normalized cross-correlation and display it as a surface plot. 
    % The peak of the cross-correlation matrix occurs where the sub_images are 
    % best correlated. normxcorr2 only works on grayscale images, so we pass it 
    % the red plane of each sub image. 

    c = normxcorr2(sub_automated(:,:,1),sub_manual(:,:,1)); 
    figure (10), surf(c), shading flat 

    %Step 4: Find the Total Offset Between the Images 
    %The total offset or translation between images depends on the location 
    %of the peak in the cross-correlation matrix, and on the size and position 
    %of the sub images. 
    % offset found by correlation 

    [max_c, imax] = max(abs(c(:))); 
    [ypeak, xpeak] = ind2sub(size(c),imax(1)); 
    corr_offset = [(xpeak-size(sub_automated,2)) 
        (ypeak-size(sub_automated,1))]; 
    % relative offset of position of subimages 
    rect_offset = [(rect_manual(1)-rect_automated(1)) 
        (rect_manual(2)-rect_automated(2))]; 
    % total offset 
    offset = corr_offset + rect_offset; 
    xoffset = offset(1); 
    yoffset = offset(2); 

    %Step 5: See if the Onion Image was Extracted from the Peppers Image 
    %Figure out where onion falls inside of peppers. 

    xbegin = round(xoffset+1); 
    xend = round(xoffset+ size(img_automated_gray,2)); 
    ybegin = round(yoffset+1); 
    yend = round(yoffset+size(img_automated_gray,1)); 
    % extract region from peppers and compare to onion 
    extracted_automated =img_manual(ybegin:yend,xbegin:xend,:); 
    if isequal(img_automated_gray,extracted_automated) 
     disp('extracted_automated.png was extracted from img_automated.png') 
    end 

    %Step 6: Pad the Onion Image to the Size of the Peppers Image 
    %Pad the automated image to overlay on manual, using the offset determined above. 

    recovered_automated = uint8(zeros(size(img_manual))); 
    recovered_onion(ybegin:yend,xbegin:xend,:) = img_automated_gray; 
    figure(11), imshow(recovered_automated) 
    figure (12), imshowpair(img_manual(:,:,1),recovered_automated,'blend') 

Answer 1

這個答案可能是不完整的，但你已經包含的信息量，我有這個分享到：

1. 這將是有趣的，知道什麼樣的兩個失真您正試圖註冊展覽的圖像。我發現你已經使用'相似性'作爲transformation type。還有其他轉換類型可能更適合您的圖像，儘管選擇了足夠的控制點並且位置準確，但出現這種錯誤並不會給您一個好的結果。
2. 的MATLAB documentation列出了其他方法來註冊兩個圖像，並根據功能在您的圖片，其他選項之一類型：基於即基於強度（用imregister）或功能（使用一組功能從電腦視覺系統工具箱）可能更準確。
3. 要將圖像裁剪爲相同尺寸，您可以像使用imshowpair一樣顯示它們，然後使用imcrop設置您想要的尺寸。 imshowpair顯示已註冊對的所有像素，以便您的最終結果始終是顯示內容的子部分。