Green Pixels not detected

Hello,

I need to find green pixels, and extract the leaf from the image. However, a dark green leaf is not detected in image as Green, so as not in Green channel. I tried histogram equalization and contrast adjustment, but it did not work. I do not understand why this green pixels are not included. Probably, they are being close to dark, it might be counted as black pixels.

Could you please help me, what can I do? How can I include those dark green pixels in green channel? Thanks a lot.

Below I add related image.

zoomed image: