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Mat::convertTo

asked 2016-09-17 23:40:32 -0600

I have read the documentation for convertto but i can't seem to understand the scale argument. What is its purpose? After testing it, the size of the mat object is still the same. So what does it do?

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answered 2016-09-18 00:59:36 -0600

berak gravatar image

the scale factor is applied to the (pixel) values, not to the size of the Mat.

an example:

Mat m1(3,3,CV_32F, 2.0f);
cerr << m1 << endl;

[2, 2, 2;
  2, 2, 2;
  2, 2, 2]

Mat m2;
m1.convertTo(m2, CV_8U, 0.5);
cerr << m2 << endl;

[1, 1, 1;
  1, 1, 1;
  1, 1, 1]
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Oh, I see, thank you very much !

Heinrich gravatar imageHeinrich ( 2016-09-19 04:51:44 -0600 )edit

How does it handle overflows then like what if it was Mat m1 with type CV_32F and values [2, 2, 2; 2, 2, 2; 2, 2, 2] then we do m1.convertTo(m1, CV_8UC1, 255); I believe this would lead to [510, 510, 510; 510, 510, 510; 510, 510, 510] If im not mistaken. But unsigned ints only have a max value of 255? so is it set to 255 if it exceeds the maximum possible value?

Heinrich gravatar imageHeinrich ( 2016-09-19 04:57:11 -0600 )edit

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Asked: 2016-09-17 23:39:42 -0600

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Last updated: Sep 18 '16