First public commit.

lenser/coco3/convert/gr4.py

@@ -0,0 +1,24 @@
+"""CoCo 3 GIME 320x192, 4 colours from the 64-colour palette (more resolution,
+fewer colours than gr16)."""
+from __future__ import annotations
+
+from ...convert.base import Conversion, perceptual_error
+from . import _common
+
+WIDTH, HEIGHT = 320, 192
+PIXEL_ASPECT = 1.0
+NCOL = 4
+CRES = 1
+
+
+def convert(img_rgb, palette_name="gime", dither_mode="floyd",
+            intensive=False, base_color=None):
+    pen, inks, idx, img_lab, plab, prgb = _common.render(img_rgb, NCOL, dither_mode)
+    screen = _common.PACK[CRES](pen)
+    return Conversion(
+        mode="gr4", width=WIDTH, height=HEIGHT, pixel_aspect=PIXEL_ASPECT,
+        index_image=idx, data=screen, data_addr=0x4000, viewer="coco3",
+        preview_rgb=prgb[idx], error=perceptual_error(idx, img_lab, plab),
+        meta={"palette": "gime", "dither": dither_mode, "cres": CRES,
+              "inks": inks, "border": inks[0] if inks else 0},
+    )