What is blobFromImage?
cv2.dnn.blobFromImage(image, scalefactor, size, mean, swapRB, crop, ddepth) -> retval creates 4-dimensional blob from image. Optionally resizes and crops image from center, subtract mean values, scales values by scalefactor, swap Blue and Red channels. where
image : Input image.
scalefactor : Multiplier for images values.
size : Spatial size for output image.
mean : Scalar with mean values which are subtracted from channels. Values are intended to be in (mean-R, mean-G, mean-B) order if image has BGR ordering and swapRB is true.
swapRB : Flag which indicates that swap first and last channels in 3-channel image is necessary.
crop : Flag which indicates whether image will be cropped after resize or not.
ddepth : Depth of output blob. Choose CV_32F or CV_8U.
retval : 4-dimensional Mat with NCHW dimensions order.