How to make triangle for a synthetic image in gray scale

Question

Tabish Raza 2013-3-18

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https://ww2.mathworks.cn/matlabcentral/answers/67664-how-to-make-triangle-for-a-synthetic-image-in-gray-scale

编辑： Walter Roberson 2017-2-18

Helo me trying to make a synthetic image in gray scale with some rectangular shape and triangle but have trouble how to make triangle.

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Answer 1

Image Analyst 2013-3-19

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https://ww2.mathworks.cn/matlabcentral/answers/67664-how-to-make-triangle-for-a-synthetic-image-in-gray-scale#answer_79213

在 MATLAB Online 中打开

Try this:

rows = 240;
columns = 320;
grayImage = zeros(rows, columns, 'uint8');
xCoords = [100 200 300];
yCoords = [80 160 80];
mask = poly2mask(xCoords, yCoords, rows, columns);
grayImage(mask) = 150; % or whatever value you want.
imshow(grayImage);

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Tabish Raza 2013-3-19

thanx much

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Answer 2

Walter Roberson 2013-3-19

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https://ww2.mathworks.cn/matlabcentral/answers/67664-how-to-make-triangle-for-a-synthetic-image-in-gray-scale#answer_79197

poly2roi()

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Answer 3

Benhassine Nasser edinne 2017-2-18

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https://ww2.mathworks.cn/matlabcentral/answers/67664-how-to-make-triangle-for-a-synthetic-image-in-gray-scale#answer_255330

thank you very mutch

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Answer 4

Benhassine Nasser edinne 2017-2-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/67664-how-to-make-triangle-for-a-synthetic-image-in-gray-scale#answer_255331

编辑：Walter Roberson 2017-2-18

在 MATLAB Online 中打开

you can make this i.e

fname = uigetfile('*.*'); % gray scale image
Io = imread(fname);
I=Io;
xCoords = [200 512 512];
yCoords = [512 128 512];
mask = poly2mask(xCoords, yCoords, size(I,1), size(I,2));
I(mask) = 0;
Iresult=I;
subplot(1,3,1);imshow(Io) ;title('original image'); 
subplot(1,3,2);imshow(mask) ;title('triangl mask');
subplot(1,3,3);imshow(Iresult) ;title('Result image');