Codex
81 lines
2.4 KiB
Python
81 lines
2.4 KiB
Python
from __future__ import annotations
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from dataclasses import asdict, dataclass
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from pathlib import Path
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import numpy as np
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from PIL import Image
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@dataclass(frozen=True)
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class QualityMetrics:
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path: str
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width: int
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height: int
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alpha_min: int
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alpha_max: int
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alpha_mean: float
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nonzero_alpha_pixels: int
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edge_pixels: int
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edge_green_excess_mean: float
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edge_green_excess_p95: float
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edge_green_excess_max: float
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def to_dict(self) -> dict:
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return asdict(self)
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def measure_rgba(path: str | Path) -> QualityMetrics:
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image = Image.open(path).convert("RGBA")
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arr = np.asarray(image).astype(np.float32) / 255.0
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rgb = arr[..., :3]
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alpha = arr[..., 3]
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edge = (alpha > 0.02) & (alpha < 0.98)
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green_excess = np.maximum(rgb[..., 1] - np.maximum(rgb[..., 0], rgb[..., 2]), 0.0)
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edge_values = green_excess[edge]
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if edge_values.size:
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edge_mean = float(edge_values.mean())
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edge_p95 = float(np.percentile(edge_values, 95))
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edge_max = float(edge_values.max())
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else:
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edge_mean = edge_p95 = edge_max = 0.0
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alpha_u8 = (alpha * 255.0).round().astype(np.uint8)
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return QualityMetrics(
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path=str(path),
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width=image.width,
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height=image.height,
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alpha_min=int(alpha_u8.min()),
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alpha_max=int(alpha_u8.max()),
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alpha_mean=float(alpha_u8.mean()),
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nonzero_alpha_pixels=int((alpha_u8 > 0).sum()),
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edge_pixels=int(edge.sum()),
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edge_green_excess_mean=edge_mean,
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edge_green_excess_p95=edge_p95,
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edge_green_excess_max=edge_max,
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)
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def assert_quality(
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metrics: QualityMetrics,
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max_edge_green_excess_p95: float | None = None,
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require_alpha_range: bool = True,
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) -> list[str]:
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failures: list[str] = []
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if require_alpha_range:
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if metrics.alpha_min != 0:
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failures.append(f"alpha_min is {metrics.alpha_min}, expected 0")
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if metrics.alpha_max != 255:
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failures.append(f"alpha_max is {metrics.alpha_max}, expected 255")
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if metrics.nonzero_alpha_pixels <= 0:
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failures.append("nonzero alpha pixel count is 0")
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if (
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max_edge_green_excess_p95 is not None
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and metrics.edge_green_excess_p95 > max_edge_green_excess_p95
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):
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failures.append(
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"edge_green_excess_p95 "
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f"{metrics.edge_green_excess_p95:.4f} exceeds {max_edge_green_excess_p95:.4f}"
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)
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return failures
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