c++ - Add transparency when drawing a rectangle in opencv -

c++ - Add transparency when drawing a rectangle in opencv -

i trying paint rectangles in locations face detection algorithm locate faces. want utilize alpha transparency in order draw rectangles. have found in opencv documentation next in here: note functions not back upwards alpha-transparency when target image 4-channel. in case, color[3] copied repainted pixels. thus, if want paint semi-transparent shapes, can paint them in separate buffer , blend main image.

how possible blend main image buffer image? , means buffer image?

you can utilize opencv addweighted function blend image. refer documentation of function. can provide function amount of transparency want have.

here tutorial so.

c++ opencv rectangles