123 lines
4.8 KiB
Dart
123 lines
4.8 KiB
Dart
import 'dart:math' as math;
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import 'dart:typed_data';
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import 'detection_result.dart';
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/// 运行时视觉先验：对低置信度野鸡框做多线索过滤，降低户外误报。
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///
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/// 仅对 score < [maxScore]（0.35）的 pheasant 框生效；高分框与
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/// suspect（生境预警）不参与过滤，避免误杀。
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///
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/// 线索：
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/// - 颜色：绿色主导（草/叶）、蓝色主导（天空/水）、平坦低饱和（键盘/石头/文字）
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/// - 位置：中心在画面上部 15%（天空区）——野鸡是地栖动物，不会出现在天空
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///
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/// 采样在原始 planes 上进行（后台 isolate 内，不依赖 UI 线程）。
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class VisualPrior {
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static const double maxScore = 0.35;
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static const double skyTopRatio = 0.15;
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// 颜色判定阈值（与 tflite_detector 的 YUV 有限范围展开一致）
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static const double greenDiff = 20;
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static const double blueDiff = 10;
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static const double flatRange = 10;
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// 采样点中满足条件的比例超过即拒绝
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static const double greenRatio = 0.5;
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static const double blueRatio = 0.4;
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static const double flatRatio = 0.6;
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static List<DetectionResult> filter(
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List<DetectionResult> results, {
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required List<Uint8List> planes,
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required List<int> strides,
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required int width,
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required int height,
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required bool isBgra,
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required bool rgbaOrder,
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}) {
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if (results.isEmpty || width <= 0 || height <= 0) return results;
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final kept = <DetectionResult>[];
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for (final r in results) {
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final lowConfPheasant = r.label == 'pheasant' && r.score < maxScore;
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if (lowConfPheasant &&
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_reject(r, planes, strides, width, height, isBgra, rgbaOrder)) {
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continue;
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}
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kept.add(r);
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}
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return kept;
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}
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static bool _reject(DetectionResult r, List<Uint8List> planes,
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List<int> strides, int width, int height, bool isBgra, bool rgbaOrder) {
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// 位置线索：detectRaw 输出为图像坐标系，centerY 直接可判天空区
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if (r.centerY < skyTopRatio) return true;
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// 颜色线索：框中心 ±20% 区域 5×5 采样（小框采样点重合也没关系）
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final cx = (r.centerX * width).round().clamp(0, width - 1).toInt();
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final cy = (r.centerY * height).round().clamp(0, height - 1).toInt();
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final halfW = math.max(1.0, r.width * width * 0.2);
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final halfH = math.max(1.0, r.height * height * 0.2);
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var green = 0, blue = 0, flat = 0, total = 0;
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for (var gy = -2; gy <= 2; gy++) {
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for (var gx = -2; gx <= 2; gx++) {
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final px = (cx + gx * halfW / 2).round().clamp(0, width - 1).toInt();
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final py = (cy + gy * halfH / 2).round().clamp(0, height - 1).toInt();
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final (r_, g_, b_) =
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_pixel(planes, strides, px, py, width, height, isBgra, rgbaOrder);
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total++;
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final mn = math.min(r_, math.min(g_, b_));
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final mx = math.max(r_, math.max(g_, b_));
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if (g_ - r_ > greenDiff && g_ - b_ > greenDiff) green++;
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if (b_ > r_ + blueDiff) blue++;
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if (mx - mn < flatRange) flat++;
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}
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}
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if (total == 0) return false;
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if (green / total > greenRatio) return true;
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if (blue / total > blueRatio) return true;
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if (flat / total > flatRatio) return true;
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return false;
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}
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/// 读取单像素 RGB（0~255）。
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/// 8888 单平面按实际字节序取通道：BGRA=[b,g,r,a]（iOS 插件）、
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/// RGBA=[r,g,b,a]（Android 自写原生通道）——字节序写死会让 Android
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/// 低分框采样到 R/B 互换的颜色（橙色野鸡身被误判成"蓝色"）整批误杀；
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/// YUV：y 平面 + 4:2:0 半分辨率 U/V（NV12 交错或 I420 分离）。
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static (double, double, double) _pixel(List<Uint8List> planes,
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List<int> strides, int x, int y, int width, int height, bool isBgra,
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bool rgbaOrder) {
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if (isBgra) {
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final src = planes[0];
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final i = y * strides[0] + x * 4;
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final rOff = rgbaOrder ? 0 : 2;
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final bOff = rgbaOrder ? 2 : 0;
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return (src[i + rOff].toDouble(), src[i + 1].toDouble(),
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src[i + bOff].toDouble());
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}
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final yy =
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(planes[0][y * strides[0] + x] - 16.0) * (255.0 / 219.0);
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final nv12 = planes.length == 2;
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final ux = (x ~/ 2).clamp(0, width ~/ 2 - 1).toInt();
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final uy = (y ~/ 2).clamp(0, height ~/ 2 - 1).toInt();
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final uvStride = strides[1];
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final un = ((nv12
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? planes[1][uy * uvStride + ux * 2].toDouble()
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: planes[1][uy * uvStride + ux].toDouble()) -
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128.0) *
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(255.0 / 224.0);
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final vn = ((nv12
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? planes[1][uy * uvStride + ux * 2 + 1].toDouble()
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: planes[2][uy * uvStride + ux].toDouble()) -
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128.0) *
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(255.0 / 224.0);
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final r = yy + 1.402 * vn;
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final g = yy - 0.344136 * un - 0.714136 * vn;
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final b = yy + 1.772 * un;
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return (r, g, b);
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}
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}
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