RGB -> HSV VideoNode and catch red parts

hsv_red_catches_magick.py

import vapoursynth as vs
from vsmask.edge import FDOGTCanny
from vsmask.util import XxpandMode, expand, inpand, max_planes
from vsutil import join, split

core = vs.core


# clip = core.imwri.Read('unknown.png') * 10
clip = core.imwri.Read('unknown (1).png') * 10
clip = clip.resize.Point(format=vs.RGBS).std.RemoveFrameProps('_Matrix')
clip.set_output(0)


def to_hsv(clip: vs.VideoNode) -> vs.VideoNode:
    planes = split(clip.std.RemoveFrameProps('_Matrix'))
    cmax = core.std.Expr(planes, 'x y z max max')
    cmin = core.std.Expr(planes, 'x y z min min')
    Δ = core.std.Expr([cmax, cmin], 'x y -')


    rc = core.std.Expr([cmax, planes[0], Δ], 'x y - z /')
    gc = core.std.Expr([cmax, planes[1], Δ], 'x y - z /')
    bc = core.std.Expr([cmax, planes[2], Δ], 'x y - z /')
    # x y z  |  a  b  c  d    e
    # r g b  |  rc gc bc cmax Δ
    h = core.std.Expr(planes + [rc, gc, bc, cmax, Δ], 'e 0 = 0 d x = c z - d y = 2 a + c - 4 z + a - ? ? ? 6 /')
    # h = core.std.Expr(planes + [rc, gc, bc, cmax], 'cmax r = bc gc - cmax g = 2 rc + bc - 4 gc + rc - ? ? 6 /')
    h = core.std.Expr(h, 'x 0 < x 1 + x ?')
    s = core.std.Expr([Δ, cmax], 'y 0 = 0 x y / ?')
    v = cmax
    return join([h, s, v])


clip_hsv = to_hsv(clip)
clip_hsv.set_output(1)

h_thr = 20 / 255
s_hr = 80 / 255
v_thrl = 255 / 255
v_thrh = 15 / 255
cclip = core.std.Expr(split(clip_hsv), f'x {h_thr} < x 1 {h_thr} - > or y {s_hr} > and z {v_thrl} < z {v_thrh} > and and 1 0 ?')

cclip = expand(cclip, 20, 20, XxpandMode.ELLIPSE)
cclip = inpand(cclip, 15, 15, XxpandMode.ELLIPSE)

edgemask = max_planes(
    *split(FDOGTCanny().get_mask(clip).std.RemoveFrameProps('_Matrix'))
).std.Binarize(0.4).std.Maximum().std.Minimum()


edgemask.set_output(2)


final = core.std.Expr([cclip, edgemask], 'x 1 >= y 1 >= and x 0 ?')
final.set_output(3)