yellow range of colors

from skimage import color
from skimage.io import imsave

lab_img = color.rgb2lab(cimage)
copy_img = np.copy(cimage)
L_img = lab_img[:, :, 0]
A_img = lab_img[:, :, 1]
B_img = lab_img[:, :, 2]

# green a > -35
x,y,z = lab_img.shape
for xi in range(x):
    for yi in range(y):
        if lab_img[xi,yi][2] > 55 and lab_img[xi,yi][1] < 0 and lab_img[xi,yi][0] > 55:
            # this is yellow color
            # copy_img[xi, yi] = [255,255,255]
            pass
        else:
            copy_img[xi, yi] = [255,255,255]
        
fig, ax = plt.subplots(figsize=(20,20))
ax.imshow(copy_img)