pythonopencvrgbhsl

OpenCV converts HSL to RGB

I am using OpenCV python to convert a single HSL value to RGB value.

Since there is no HSL2RGB flag, so I used HLS2RGB flag. I assumed HSL and HLS refers to the same color space but just flipping the S and L values. Is that right?

So here is my attempt:

import cv2

hls = (0, 50, 100)  # This is color Red
rgb = cv2.cvtColor( np.uint8([[hls]] ), cv2.COLOR_HLS2RGB)[0][0]

After conversion, rgb value is [70, 30, 30]

However, when I checked this RGB value on online RGB picker, the color is dark brown.

Any idea where could go wrong in the conversion? Thanks

Solution

  • The HLS ranges in OpenCV are

    H -> 0 - 180
L -> 0 - 255
S -> 0 - 255

    So if the HLS range you are using are

    H -> 0 - 360
L -> 0 - 100
S -> 0 - 100

    you have to convert it to OpenCV's range first

    hls = (0, 50, 100)
hls_conv = (hls[0]/2, hls[1]*2.55, hls[2]*2.55)
rgb = cv2.cvtColor(np.uint8([[hls_conv]]), cv2.COLOR_HLS2RGB)[0][0]

    which will result in rgb being [254, 0, 0]