OpenCV 2.4 putText() and Scalar understanding

Question

I'm using OpenCV 2.4.11 in C++. I want to display a text with the putText() function on my picture.
For example:

putText(imageOutput,"x:",Point(pos[0],pos[1]),1,1,Scalar(255,0,0),2);

What does the Scalar input do? Is there an alternative input instead of Scalar?

it's the text color, b,g,r. (and not a function, but a constructor of the Scalar class) — berak, Mar 15 '15 at 16:02
@berak Thank you! Is there an other way to define the color? — black, Mar 15 '15 at 16:33

score 2 · Accepted Answer · answered Mar 16 '15 at 08:21

Your code:

putText(imageOutput,"x:",Point(pos[0],pos[1]),1,1,Scalar(255,0,0),2);

Your question:

What does the Scalar function do?

You are creating a Scalar object, you can see the documentation here

If you want to create a BGR (full colour) image then you can initialise the Scalar with Scalar(B,G,R). However if you only want a greyscale image all you need to do is initialise it with your greyscale value:

Scalar(greyScaleValue);

so your code would be:

putText(imageOutput,"x:",Point(pos[0],pos[1]),1,1,Scalar(30),2);

for a greyscale value of 30.

OpenCV 2.4 putText() and Scalar understanding

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