fix(post): remove max_chars budget cap for ASCII art

wayd/scripts/img2ascii.py

@@ -12,14 +12,15 @@
 
 Options:
   --image PATH       Image file (JPEG, PNG, GIF, WebP, DNG, …)
-  --width N          Width in chars (default: 100). Height auto-calculated.
+  --width N          Width in chars (default: 80). Height auto-calculated.
   --invert           Invert brightness (for light-background images).
   --caption TEXT     Text appended below the art (2 blank lines separator).
-  --edge-weight F    How much edge detection to blend in, 0.0–1.0 (default 0.4).
-                     Higher = more defined outlines like asciiart.eu.
+  --threshold N      Brightness cutoff 0-255; pixels above this become spaces
+                     (default: 140). Lower = more sparse; higher = denser.
+  --edge-weight F    How much edge detection to blend in, 0.0–1.0 (default 0.3).
   --sharpen          Apply sharpening before conversion (default: on).
   --no-sharpen       Disable sharpening.
-  --contrast F       Contrast multiplier (default: 1.3). 1.0 = no change.
+  --contrast F       Contrast multiplier (default: 2.2). 1.0 = no change.
 """
 
 from __future__ import annotations
@@ -31,27 +32,43 @@
 sys.path.insert(0, str(Path(__file__).resolve().parent))
 import shared  # noqa: E402
 
-# Dense 70-char gradient from dark to light (dark terminal).
-# Derived from the classic Paulm gradient used by most quality converters.
-_RAMP_DARK = r'$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\|()1{}[]?-_+~<>i!lI;:,"^`\'. '
-_RAMP_LIGHT = _RAMP_DARK[::-1]
+# Sparse character set — dark to light (last char = space for bright areas).
+# Matches asciiart.eu "Space Density 6" aesthetic: lots of whitespace,
+# dense chars only in shadows/edges. Far more legible than a 70-char ramp.
+_CHARS_DARK = "@%#*+=-:. "
+_CHARS_LIGHT = _CHARS_DARK[::-1]
 
 
-def _px(luminance: int, ramp: str) -> str:
-    return ramp[int(luminance / 255 * (len(ramp) - 1))]
+def _px(luminance: int, threshold: int, chars: str) -> str:
+    """Return a character for a given pixel luminance.
+
+    Pixels brighter than `threshold` become spaces (light/sky areas).
+    Darker pixels are mapped across the non-space portion of `chars`.
+    """
+    if luminance >= threshold:
+        return " "
+    idx = int(luminance / threshold * (len(chars) - 2))
+    return chars[max(0, min(len(chars) - 2, idx))]
 
 
 def image_to_ascii(
     image_path: str,
-    width: int = 100,
+    width: int = 80,
     invert: bool = False,
-    edge_weight: float = 0.4,
+    threshold: int = 140,
+    edge_weight: float = 0.3,
     sharpen: bool = True,
-    contrast: float = 1.3,
+    contrast: float = 2.2,
     caption: str = "",
     max_chars: int | None = None,
 ) -> str:
-    """Return ASCII art string. Raises ValueError on failure."""
+    """Return ASCII art string. Raises ValueError on failure.
+
+    Uses a sparse character set with a brightness threshold — pixels above
+    the threshold become spaces, producing the airy asciiart.eu aesthetic
+    where light areas (sky, backgrounds) are empty and only shadows/edges
+    carry characters.
+    """
     try:
         from PIL import Image, ImageEnhance, ImageFilter  # type: ignore[import]
     except ImportError:
@@ -64,25 +81,19 @@ def image_to_ascii(
     except Exception as exc:
         raise ValueError(f"Cannot open image: {exc}")
 
-    # Convert to RGB then grayscale (handles RGBA, P, CMYK, DNG/TIFF, etc.)
     img = img.convert("RGB")
 
-    # --- Preprocessing (mimics asciiart.eu quality pipeline) ---
-
     if sharpen:
-        img = ImageEnhance.Sharpness(img).enhance(2.0)
-
+        img = ImageEnhance.Sharpness(img).enhance(3.0)
     if contrast != 1.0:
         img = ImageEnhance.Contrast(img).enhance(contrast)
 
     gray = img.convert("L")
 
-    # Compute target height preserving aspect ratio.
-    # Terminal chars are ~2:1 tall:wide; 0.45 corrects for that.
+    # Terminal chars are ~2:1 tall:wide; 0.45 corrects aspect ratio.
     aspect = img.height / img.width
     height = max(1, int(width * aspect * 0.45))
 
-    # Shrink to fit max_chars budget if given (art-only chars, no caption).
     if max_chars is not None:
         caption_cost = len(caption) + 2 if caption else 0
         while width >= 20:
@@ -91,32 +102,26 @@ def image_to_ascii(
             width = int(width * 0.9)
             height = max(1, int(width * aspect * 0.45))
 
-    # Resize both base image and edge map to the target size.
     base = gray.resize((width, height), Image.LANCZOS)
-
-    # Edge detection: find edges on a slightly blurred version for clean lines.
     edge_src = gray.filter(ImageFilter.GaussianBlur(1)).filter(ImageFilter.FIND_EDGES)
     edges = edge_src.resize((width, height), Image.LANCZOS)
 
-    # Blend: final_lum = base * (1 - w) + edges * w
-    # Edge pixels push luminance toward dark (dense chars = outlines).
     base_px = base.tobytes()
     edge_px = edges.tobytes()
 
-    ramp = _RAMP_LIGHT if invert else _RAMP_DARK
+    chars = _CHARS_LIGHT if invert else _CHARS_DARK
     lines: list[str] = []
 
     for row in range(height):
-        chars = []
+        row_chars = []
         for col in range(width):
             idx = row * width + col
             b = base_px[idx]
             e = edge_px[idx]
-            # Invert edge contribution so edges → darker chars (denser).
             blended = int(b * (1 - edge_weight) + (255 - e) * edge_weight)
             blended = max(0, min(255, blended))
-            chars.append(_px(blended, ramp))
-        lines.append("".join(chars))
+            row_chars.append(_px(blended, threshold, chars))
+        lines.append("".join(row_chars).rstrip())  # trim trailing spaces
 
     art = "\n".join(lines)
     if caption:
@@ -127,13 +132,14 @@ def image_to_ascii(
 def main() -> None:
     parser = argparse.ArgumentParser(description="High-quality image → ASCII art.")
     parser.add_argument("--image", required=True)
-    parser.add_argument("--width", type=int, default=100)
+    parser.add_argument("--width", type=int, default=80)
     parser.add_argument("--invert", action="store_true")
     parser.add_argument("--caption", default="")
-    parser.add_argument("--edge-weight", type=float, default=0.4)
+    parser.add_argument("--threshold", type=int, default=140)
+    parser.add_argument("--edge-weight", type=float, default=0.3)
     parser.add_argument("--sharpen", dest="sharpen", action="store_true", default=True)
     parser.add_argument("--no-sharpen", dest="sharpen", action="store_false")
-    parser.add_argument("--contrast", type=float, default=1.3)
+    parser.add_argument("--contrast", type=float, default=2.2)
     parser.add_argument("--max-chars", type=int, default=None)
     args = parser.parse_args()
 
@@ -142,6 +148,7 @@ def main() -> None:
             image_path=args.image,
             width=args.width,
             invert=args.invert,
+            threshold=args.threshold,
             edge_weight=args.edge_weight,
             sharpen=args.sharpen,
             contrast=args.contrast,

wayd/scripts/post.py

@@ -85,7 +85,7 @@ def cmd_check_rate_limit(_: argparse.Namespace) -> None:
 
 
 def _convert_image_to_art(image_path: str, text_len: int, max_chars: int) -> str | None:
-    """Convert image to ASCII art sized to fit within the remaining char budget.
+    """Convert image to ASCII art. Art is exempt from max_chars, so no budget cap.
 
     Returns the art string, or None if conversion fails (caller logs the error
     and continues without art so the post still goes through).
@@ -97,14 +97,8 @@ def _convert_image_to_art(image_path: str, text_len: int, max_chars: int) -> str
         shared.log_error("img2ascii not found; skipping image conversion")
         return None
 
-    # Reserve chars for: text + 2 newlines + art block markers (~20 chars overhead)
-    budget = max_chars - text_len - 20
-    if budget < 50:
-        shared.log_error("not enough char budget for ASCII art after text")
-        return None
-
     try:
-        return image_to_ascii(image_path=image_path, max_chars=budget)
+        return image_to_ascii(image_path=image_path)
     except Exception as exc:
         shared.log_error(f"img2ascii failed for {image_path!r}: {exc}")
         return None