Grayscale conversion algorithm of OpenCV's imread() -
what grayscale conversion algorithm opencv's
cv::imread("image.jpg", cv::imread_grayscale);
use?
in opencv 3.0:
cv::imread_color
: image decompressedcv::jpegdecoder
jcs_rgb
(three channel image) ,icvcvt_rgb2bgr_8u_c3r()
function swap red , blue channels in order bgr format.cv::imread_grayscale
: image decompressedcv::jpegdecoder
jcs_grayscale
(one channel image), details of color conversion , other preprocessing/postprocessing handled libjpeg. finally, decompressed data copied internal buffer of givencv::mat
.
ergo no cv::cvtcolor()
called after reading image cv::imread_grayscale
.