I know there is a addWeighted method. But what I need is draw many lines, every line with different transparency.
Which means, can not using N mask to draw then addWeighted, that too slow speed.
To draw a line on BGR format image:
line(img_a, p1, p2, c, 2, CV_AA);
It does not add alpha even c is Scalar with alphas.
I convert image from BGR to BGRA with 4 channels, but the line still full with color rather than with transparency.
Any body could help me out with simply what I need?
serveral lines with difference transparency on a color image (not using addWeighted that is slow I have 500 lines).