First public commit.

lenser/vic20/palette.py

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+"""Commodore VIC-20 (VIC 6560/6561) 16-colour palette.
+
+Calibrated against MAME's `vic20`: a display-setup cartridge cycled the global
+background ($900F bits 4-7) over all 16 values while a blank-character cell was
+sampled with the emulator's screen pixel reader (NORMAL mode -- $900F bit 3 = 1;
+with bit 3 = 0 the chip is in REVERSE mode and blank cells show the foreground).
+
+The VIC has 16 colours but the per-cell *foreground* (colour RAM, 3 bits) is
+limited to the first 8; the global background / border / auxiliary may be any of
+the 16.  Colours 8-15 are lighter variants of 0-7.
+"""
+
+from __future__ import annotations
+
+import numpy as np
+
+from ..palette import srgb_to_lab
+
+VIC = np.array([
+    (0x00, 0x00, 0x00),   # 0  black
+    (0xFF, 0xFF, 0xFF),   # 1  white
+    (0xF0, 0x00, 0x00),   # 2  red
+    (0x00, 0xF0, 0xF0),   # 3  cyan
+    (0x60, 0x00, 0x60),   # 4  purple
+    (0x00, 0xA0, 0x00),   # 5  green
+    (0x00, 0x00, 0xF0),   # 6  blue
+    (0xD0, 0xD0, 0x00),   # 7  yellow
+    (0xC0, 0xA0, 0x00),   # 8  orange
+    (0xFF, 0xA0, 0x00),   # 9  light orange
+    (0xF0, 0x80, 0x80),   # 10 pink
+    (0x00, 0xFF, 0xFF),   # 11 light cyan
+    (0xFF, 0x00, 0xFF),   # 12 light purple
+    (0x00, 0xFF, 0x00),   # 13 light green
+    (0x00, 0xA0, 0xFF),   # 14 light blue
+    (0xFF, 0xFF, 0x00),   # 15 light yellow
+], dtype=np.float64)
+
+# Foreground (colour RAM, 3-bit) is limited to the first 8 colours.
+FG_USABLE = list(range(8))
+# Background / border / auxiliary may be any of the 16.
+BG_USABLE = list(range(16))
+
+
+def get_palette() -> np.ndarray:
+    return VIC
+
+
+def palette_lab() -> np.ndarray:
+    return srgb_to_lab(VIC)