how can I detect black(specific) color in this image

how can I detect black(specific) color in this image

I want to detect from color and draw a lot of bounding box of a suitable size so that the area is not clipped like image 111

[DGM]

Can you provide a copy of the test image without the annotations?

[Alexai]

I uploaded it again in the attached file.

Answer 1

[yanqi liu]

img = imread('https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/910360/original%20image.jpg');
I = rgb2gray(img);
bw = ~imbinarize(I,'adaptive','ForegroundPolarity','dark','Sensitivity',0.35);
[L,~] = bwlabel(bw);
figure; imshow(img, []); hold on; 
h = imshow(label2rgb(L));
set(h, 'AlphaData', 0.5);
bw2 = imclose(bw, strel('disk', 5));
bw2 = bwareaopen(bw2, 20);
[L2,~] = bwlabel(bw2);
stats = regionprops(L2);
hold on;
for i = 1 : length(stats)
    hold on; rectangle('position', stats(i).BoundingBox, 'EdgeColor', 'g', 'LineWidth', 2)
end