Working Python version for Commodore.

c64view/convert/hires.py

@@ -0,0 +1,64 @@
+"""Hires bitmap mode: 320x200, two colours per 8x8 cell.
+
+Data file layout (PRG, load $2000), matched to viewer/hires.s:
+    $2000  bitmap     8000 bytes  (VIC reads here directly)
+    $3F40  screen RAM 1000 bytes  (viewer copies to $0400)
+"""
+
+from __future__ import annotations
+
+import numpy as np
+
+from .. import dither, palette as pal
+from . import base
+
+WIDTH, HEIGHT = 320, 200
+CELL_W, CELL_H = 8, 8
+PIXEL_ASPECT = 1.0
+DATA_LOAD = 0x2000
+
+
+def convert(img_rgb: np.ndarray, palette_name="colodore",
+            dither_mode="bayer", intensive=False) -> base.Conversion:
+    plab = pal.palette_lab(palette_name)
+    img_lab = pal.srgb_to_lab(img_rgb)
+
+    cells, rows, cols = base.cells_lab(img_lab, CELL_W, CELL_H)
+    dist = base.cell_distance(cells, plab)
+    sets, _ = base.select_cell_sets(dist, range(16), n_free=2)
+
+    allowed = base.per_pixel_allowed(sets, rows, cols, CELL_W, CELL_H, HEIGHT, WIDTH)
+    index_image = dither.quantize(img_lab, allowed, plab, dither_mode).astype(np.uint8)
+
+    bitmap, screen = _encode(index_image, sets, rows, cols)
+    payload = bytes(bitmap) + bytes(screen)
+
+    conv = base.Conversion(
+        mode="hires", width=WIDTH, height=HEIGHT, pixel_aspect=PIXEL_ASPECT,
+        index_image=index_image, data=payload, viewer="hires",
+        error=base.mean_error(index_image, img_lab, plab),
+        meta={"palette": palette_name, "dither": dither_mode},
+    )
+    # Standard OCP Art Studio hires file (load $2000): bitmap, screen, border.
+    conv.extra_files = [("picture.art", base.prg(0x2000, payload + b"\x00"))]
+    return conv
+
+
+def _encode(index_image, sets, rows, cols):
+    """Build the 8000-byte bitmap and 1000-byte screen RAM."""
+    bitmap = np.zeros(8000, dtype=np.uint8)
+    screen = np.zeros(1000, dtype=np.uint8)
+    for cr in range(rows):
+        for cc in range(cols):
+            ci = cr * cols + cc
+            bg_col, fg_col = int(sets[ci, 0]), int(sets[ci, 1])
+            screen[ci] = ((fg_col & 0x0F) << 4) | (bg_col & 0x0F)
+            base_addr = cr * 320 + cc * 8
+            block = index_image[cr * 8:cr * 8 + 8, cc * 8:cc * 8 + 8]
+            for r in range(8):
+                row = block[r]
+                byte = 0
+                for x in range(8):
+                    byte = (byte << 1) | (1 if row[x] == fg_col else 0)
+                bitmap[base_addr + r] = byte
+    return bitmap, screen