CODEWITHSUNDEEP
c++visual-studio-2010opencv
Zeus M
Zeus M

Reputation: 427

Declaring a Matrix with the same values with openCV

I have declared a Matrix which contains values equal to 1: cv::Mat mat_cal = cv::Mat::ones(width, height, CV_8U);

Now I want to to be multiplied by a constant, I mean, one matrix whose values are equal to A=0.3 Then I wrote: cv::Mat mat_cal = cv::Mat::ones(width, height, CV_8U)*A;

But, the result? Matrix of 0 0 0 0 0 0 0 0.....

Any solution?

Upvotes: 0

Views: 578

Answers (2)

n00dle
n00dle

Reputation: 6043

Part of your problem is your matrix type is CV_8U which is an 8-bit unsigned integer - as such 0.3 gets trunctated to 0. Instead set it to CV_32F (32-bit floating point).

Also, if I remember, when multiplying by a scalar, you do as below. Multiplying 2 matrices doesn't work the same way:

float A = 0.3;
cv::Mat mat_cal = cv::Mat::ones(width, height, CV_32F)*A;

Upvotes: 1

berak
berak

Reputation: 39796

char i = 1;
i *= 0.3;

result ? 0

it's just plain old integer rounding.

if you want a Mat with double or float values, use the right type in the first place:

cv::Mat::ones(width, height, CV_32F)*0.3f; // float

or:

cv::Mat::ones(width, height, CV_64F)*0.3;  // double

Upvotes: 0

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