Raster Sequence (Nake)

Math essence

A position-dependent 6×6 transition matrix T(pos) = T_base + bias(pos)·(T_centre − T_base), where bias(pos) = 1 − 4(pos − 0.5)², is used to draw a chain of length cols·rows from the six-sign alphabet. The chain is then placed into a cols×rows raster in row-major order. Increasing non_stationarity widens the difference between the centre and the ends of the chain, so the long vertical strokes cluster in the middle of the picture exactly as in Nake's original '7.3-1'.

Parameters

Reference

First 60 lines of reference.py. Full source: library_external/generative_pioneers_2/nake_raster_sequence/reference.py

from __future__ import annotations

from typing import ClassVar

import imageio.v2 as imageio
import numpy as np


class NakeRasterSequence:
    family: ClassVar[str] = "generative_pioneers_2"
    sketch: ClassVar[str] = "nake_raster_sequence"

    SIGN_EMPTY = 0
    SIGN_VERT = 1
    SIGN_HORIZ = 2
    SIGN_DIAG_R = 3
    SIGN_DIAG_L = 4
    SIGN_DOT = 5

    SIGNS = (
        "empty",
        "vertical",
        "horizontal",
        "diag_right",
        "diag_left",
        "dot",
    )

    BASE_TRANSITION = np.array(
        [
            [0.55, 0.10, 0.05, 0.10, 0.10, 0.10],
            [0.55, 0.20, 0.05, 0.10, 0.05, 0.05],
            [0.55, 0.05, 0.20, 0.05, 0.10, 0.05],
            [0.55, 0.10, 0.10, 0.15, 0.05, 0.05],
            [0.55, 0.05, 0.10, 0.05, 0.15, 0.10],
            [0.55, 0.10, 0.10, 0.10, 0.05, 0.10],
        ],
        dtype=np.float32,
    )

    def __init__(
        self,
        dim: int = 512,
        cols: int = 32,
        rows: int = 32,
        cell_size: int = 14,
        margin: float = 0.06,
        non_stationarity: float = 0.7,
        stochasticity: float = 1.0,
        bg_color: tuple[int, int, int] = (240, 235, 220),
        ink_color: tuple[int, int, int] = (12, 14, 22),
        palette: tuple[tuple[int, int, int], ...] = (
            (12, 14, 22),
            (200, 40, 60),
            (30, 90, 200),
            (240, 200, 40),
        ),
        seed: int | None = None,
    ) -> None:
        self.dim = dim