Hide flags in other flags using gamma

import functools
import numpy as np
from scipy.optimize import root_scalar
from PIL import Image

trans_flag = [[91, 206, 250],[245, 169, 184],[255, 255, 255],[245, 169, 184],[91, 206, 250]]

def parse_flag(s):
    r=[]
    for w in s.split():
        c=[]
        for i in range(3):
            c.append(int(w[i*2:i*2+2],16))
        r.append(c)
    return r

demigirl_flag = parse_flag('7f7f7f c3c3c3 ffaec9 ffffff ffaec9 c3c3c3 7f7f7f')

@functools.lru_cache()
def solve_color(y, z, i):
    sy = y / 255
    sz = z / 255
    x = root_scalar((lambda x:x**2.2+(2*sy-x)**2.2-2*sz), x0=0.5, x1=0.7)
    x = int(round(255*min(1,max(0,x.root))))
    if i:
        x = max(0,min(255,2*y-x))
    return x

def gamma_flag(lx, ly, fp, stripes_y, stripes_z, desat_y, desat_z):
    stripes_y = np.array(list(map(list, stripes_y)))
    stripes_z = np.array(list(map(list, stripes_z)))
    stripes_y = np.array(stripes_y+(127-stripes_y)*desat_y,np.uint8)
    ztg=255*(np.mean(stripes_y)/255)**2.2
    stripes_z = np.array(stripes_z+(ztg-stripes_z)*desat_z,np.uint8)
    ny = stripes_y.shape[0]
    nz = stripes_z.shape[0]
    pix = np.zeros((ly, lx, 3), dtype=np.uint8)
    for y in range(ly):
        sy = stripes_y[y*ny//ly]
        sz = stripes_z[y*nz//ly]
        for x in range(lx):
            f = (x+y)&1
            for j in range(3):
                pix[y][x][j] = solve_color(sy[j], sz[j], f)
    im = Image.fromarray(pix)
    im.save(fp)

gamma_flag(1536, 1024, 'gamma_trans_demigirl.png', trans_flag, demigirl_flag, 0.93,0.86)