Matlab 把 ROI mask 以一定透明度叠加到黑白图像上

function converted_im = mask_overlay_im(im,mask)
    % 把mask叠加到图像上

    im = single(im);
    HSV = zeros([size(im), 3], 'single');

    if max(im(:)) > 1
        v = im / 255;
    else
        v= im;
    end

    HSV(:,:,3) = v; % value

    n_roi = max(mask(:));
    hues = linspace(0, 1, n_roi+1);
    hues = hues(randperm(n_roi));

    for n = 1:max(mask(:))
        mask_indices = (mask == n);
        HSV(mask_indices) = hues(n); % hue
        HSV(:,:,2) = HSV(:,:,2) .* ~mask_indices +  0.4*mask_indices; % saturation
    end

    converted_im = uint8(hsv2rgb(HSV) * 255);
end

% test mask overlay to image
colored_mask = mask_to_rgb(matlab_mask);
binary_mask = matlab_mask>0;


figure
imshow(im,[])
hold on 
alpha = 0.3;
h = imshow(colored_mask,[])
h.AlphaData=binary_mask*alpha;