First public commit.

lenser/apple/convert/dhgr.py

@@ -0,0 +1,60 @@
+"""Apple //e Double Hi-Res: 140x192, 16 colours (no per-cell limit).
+
+Each line is 560 bits = 140 four-bit colour groups, stored 7 bits per byte with
+the bytes interleaved between auxiliary and main memory (aux holds the even display
+bytes, main the odd).  Needs a //e (auxiliary memory).
+"""
+
+from __future__ import annotations
+
+import numpy as np
+
+from ... import dither, palette as c64pal
+from ...convert.base import Conversion, perceptual_error
+from .. import palette as apal
+
+WIDTH, HEIGHT = 140, 192
+PIXEL_ASPECT = 2.0
+DATA_ADDR = 0x2000
+
+
+def convert(img_rgb, palette_name="dhgr", dither_mode="floyd",
+            intensive=False, base_color=None):
+    plab = apal.dhgr_lab()
+    prgb = apal.DHGR16.astype(np.uint8)
+    img_lab = c64pal.srgb_to_lab(img_rgb)              # (192,140,3)
+
+    allowed = np.tile(np.arange(16), (HEIGHT, WIDTH, 1))
+    idx = dither.quantize(img_lab, allowed, plab, dither_mode).astype(np.int64)
+
+    aux = bytearray(0x2000)
+    main = bytearray(0x2000)
+    for y in range(HEIGHT):
+        stream = np.zeros(560, dtype=np.uint8)
+        row = idx[y]
+        for n in range(WIDTH):
+            c = int(row[n])
+            stream[4 * n + 0] = c & 1
+            stream[4 * n + 1] = (c >> 1) & 1
+            stream[4 * n + 2] = (c >> 2) & 1
+            stream[4 * n + 3] = (c >> 3) & 1
+        base = apal.hgr_row_addr(y)
+        for col in range(40):
+            ab = 0
+            mb = 0
+            for i in range(7):
+                ab |= int(stream[7 * (2 * col) + i]) << i
+                mb |= int(stream[7 * (2 * col + 1) + i]) << i
+            aux[base + col] = ab
+            main[base + col] = mb
+
+    data = bytes(main) + bytes(aux)                    # main half at $2000, aux at $4000
+    preview = np.repeat(prgb[idx], int(PIXEL_ASPECT), axis=1)
+
+    return Conversion(
+        mode="dhgr", width=WIDTH, height=HEIGHT, pixel_aspect=PIXEL_ASPECT,
+        index_image=idx.astype(np.uint16), data=data, data_addr=DATA_ADDR,
+        viewer="dhgr", preview_rgb=preview,
+        error=perceptual_error(idx, img_lab, plab),
+        meta={"palette": "dhgr", "dither": dither_mode},
+    )