HindiText-Pilot / src /data /gen_pilot.py
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Add pilot dataset: 4,000 shaped Devanagari samples + masks, fonts, generator (part 14)
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"""Generate the pilot training set.
Clean backgrounds only -- the pilot answers "can SD1.5 + a TE LoRA learn
Devanagari glyph shapes at all", so scene compositing is deliberately out of
scope (see PLAN.md §4b: that decision is deferred until the pilot reports).
Hard invariants, asserted rather than assumed:
* font em size >= MIN_EM (the measured VAE floor -- FINDINGS.md §2)
* text fits the canvas with margin
* caption fits CLIP's 77-token window, template included
* fg/bg luminance contrast is real
"""
from __future__ import annotations
import argparse
import json
import pathlib
import random
import sys
sys.path.insert(0, str(pathlib.Path(__file__).resolve().parents[1]))
import numpy as np
from PIL import Image, ImageFilter
from data.captions import make_caption
from render.shaper import load_face, render_line
RES = 512
MIN_EM = 32 # measured VAE floor; below this diacritics are destroyed
MAX_EM = 120
MARGIN = 24
MAX_TOKENS = 77
def load_words(path: pathlib.Path) -> list[str]:
out = []
for line in path.read_text(encoding="utf-8").splitlines():
line = line.strip()
if line and not line.startswith("#"):
out.append(line)
return out
def luminance(rgb) -> float:
r, g, b = [c / 255 for c in rgb]
return 0.2126 * r + 0.7152 * g + 0.0722 * b
def pick_colors(rng: random.Random) -> tuple[tuple, tuple]:
"""Foreground/background with guaranteed contrast.
Low-contrast text would be destroyed by the VAE just as surely as small
text, so this is enforced, not sampled and hoped for.
"""
for _ in range(64):
if rng.random() < 0.45: # dark on light: the common signage case
bg = tuple(rng.randint(190, 255) for _ in range(3))
fg = tuple(rng.randint(0, 70) for _ in range(3))
elif rng.random() < 0.5: # light on dark
bg = tuple(rng.randint(0, 80) for _ in range(3))
fg = tuple(rng.randint(185, 255) for _ in range(3))
else: # saturated colour pair
bg = tuple(rng.randint(0, 255) for _ in range(3))
fg = tuple(rng.randint(0, 255) for _ in range(3))
if abs(luminance(fg) - luminance(bg)) >= 0.35:
return fg, bg
return (0, 0, 0), (255, 255, 255)
def make_background(rng: random.Random, bg: tuple) -> Image.Image:
kind = rng.random()
if kind < 0.55:
return Image.new("RGB", (RES, RES), bg)
if kind < 0.85:
# linear gradient -- mild, so it never competes with the glyphs
other = tuple(max(0, min(255, c + rng.randint(-45, 45))) for c in bg)
ramp = np.linspace(0.0, 1.0, RES, dtype=np.float32)
# broadcast the ramp across the full canvas, vertically or horizontally
a = (np.tile(ramp[:, None], (1, RES)) if rng.random() < 0.5
else np.tile(ramp[None, :], (RES, 1)))[..., None]
arr = np.array(bg, dtype=np.float32) * (1 - a) + np.array(other, dtype=np.float32) * a
assert arr.shape == (RES, RES, 3), f"bad gradient shape {arr.shape}"
return Image.fromarray(arr.astype(np.uint8))
# faint noise/texture
base = np.array(Image.new("RGB", (RES, RES), bg), dtype=np.float32)
base += np.random.normal(0, 6, base.shape)
img = Image.fromarray(np.clip(base, 0, 255).astype(np.uint8))
return img.filter(ImageFilter.GaussianBlur(0.6))
def render_sample(word: str, fonts: list[str], rng: random.Random):
"""Returns (image, mask, meta) or None if no valid layout was found."""
avail = RES - 2 * MARGIN
for _ in range(12):
font = rng.choice(fonts)
# Measure once at a reference size, then solve for the largest em that
# fits. Sampling em blindly would systematically shrink long words --
# word length would end up correlated with text size in the dataset.
try:
ref = load_face(f"fonts/{font}", 64)
rm, _ = render_line(ref, word, pad=6)
except Exception:
continue
fit = int(64 * min(avail / rm.width, avail / rm.height))
hi = min(MAX_EM, fit)
if hi < MIN_EM:
continue # cannot satisfy the VAE floor here
em = rng.randint(MIN_EM, hi)
try:
face = load_face(f"fonts/{font}", em)
mask, m = render_line(face, word, pad=6)
except Exception:
continue
if mask.width > avail or mask.height > avail:
continue # rounding slop at the boundary
assert em >= MIN_EM, "VAE floor violated"
fg, bg = pick_colors(rng)
img = make_background(rng, bg)
x = rng.randint(MARGIN, RES - MARGIN - mask.width)
y = rng.randint(MARGIN, RES - MARGIN - mask.height)
img.paste(fg, (x, y), mask)
full_mask = Image.new("L", (RES, RES), 0)
full_mask.paste(mask, (x, y))
assert img.size == (RES, RES), f"bad canvas {img.size}"
return img, full_mask, {
"font": font, "em": em, "x": x, "y": y,
"w": mask.width, "h": mask.height, "glyphs": m["n_glyphs"],
}
return None
def main() -> int:
ap = argparse.ArgumentParser()
ap.add_argument("--n", type=int, default=4000)
ap.add_argument("--out", default="data/pilot")
ap.add_argument("--holdout", type=int, default=20, help="words reserved for eval")
ap.add_argument("--seed", type=int, default=0)
ap.add_argument("--masks", action="store_true", help="also write glyph masks")
args = ap.parse_args()
rng = random.Random(args.seed)
np.random.seed(args.seed)
from transformers import CLIPTokenizer
# local copy when present (offline), else pull SD1.5's own tokenizer
try:
tok = CLIPTokenizer.from_pretrained("models/clip")
except Exception:
tok = CLIPTokenizer.from_pretrained(
"stable-diffusion-v1-5/stable-diffusion-v1-5", subfolder="tokenizer")
words = load_words(pathlib.Path("corpus/pilot_words.txt"))
fonts = [l.strip() for l in pathlib.Path("configs/fonts_ok.txt")
.read_text(encoding="utf-8").splitlines() if l.strip()]
if not fonts:
print("no usable fonts -- run src/diag/font_audit.py"); return 1
# Split by WORD before anything else, so no held-out word appears in training
# in any form. Leakage here would make the eval meaningless.
shuffled = words[:]
rng.shuffle(shuffled)
holdout = sorted(shuffled[: args.holdout])
train = sorted(shuffled[args.holdout:])
out = pathlib.Path(args.out)
(out / "images").mkdir(parents=True, exist_ok=True)
if args.masks:
(out / "masks").mkdir(parents=True, exist_ok=True)
recs, skipped, over = [], 0, 0
for i in range(args.n):
word = rng.choice(train)
got = render_sample(word, fonts, rng)
if got is None:
skipped += 1
continue
img, mask, meta = got
cap = make_caption(word, rng)
n_tok = len(tok(cap)["input_ids"])
if n_tok > MAX_TOKENS: # exact check, template included
over += 1
continue
name = f"{i:06d}"
img.save(out / "images" / f"{name}.jpg", quality=95)
if args.masks:
mask.save(out / "masks" / f"{name}.png")
recs.append({"file": f"images/{name}.jpg", "text": word,
"caption": cap, "tokens": n_tok, **meta})
with (out / "metadata.jsonl").open("w", encoding="utf-8") as fh:
for r in recs:
fh.write(json.dumps(r, ensure_ascii=False) + "\n")
(out / "train_words.txt").write_text("\n".join(train) + "\n", encoding="utf-8")
(out / "holdout_words.txt").write_text("\n".join(holdout) + "\n", encoding="utf-8")
ems = [r["em"] for r in recs]
print(f"wrote {len(recs)} samples to {out}")
print(f" skipped(layout)={skipped} skipped(tokens)={over}")
print(f" train words={len(train)} holdout={len(holdout)}")
print(f" em size: min={min(ems)} max={max(ems)} mean={sum(ems)/len(ems):.1f}")
print(f" tokens : max={max(r['tokens'] for r in recs)}")
print(f" fonts used: {len({r['font'] for r in recs})}/{len(fonts)}")
print(f"\nholdout: {' '.join(holdout)}")
return 0
if __name__ == "__main__":
raise SystemExit(main())