flutter相机流ImageStream取图片偏蓝色绿红篮紫各种随机偏色BGRA8888,YUV420

siman · 2 小时前

最近又在写我的im社交了,活体检测api太贵自己写了一个本地版,我主要是活体检测和人脸是比对不是同一个人.使用CameraImage 无感拿图片
在对比时有有时正常有时错误输出图片一看图片颜色各种偏色再此做个笔记后面还会用到有需要的拿去

import 'package:camera/camera.dart';
import 'package:flutter/foundation.dart';
import 'package:image/image.dart' as imglib;
class FaceImageUtils {
static Uint8List? convertCameraImage(CameraImage cameraImage) {
if (cameraImage.format.group == ImageFormatGroup.yuv420) {
final yuvImage = convertYUV420ToImage(cameraImage);
return Uint8List.fromList(imglib.encodeJpg(yuvImage));
} else if (cameraImage.format.group == ImageFormatGroup.bgra8888) {
final bgraImage = convertBGRA8888ToImage(cameraImage);
return Uint8List.fromList(imglib.encodeJpg(bgraImage));
}
return null;
}
/// iOS BGRA8888 修复，彻底解决随机偏色
static imglib.Image convertBGRA8888ToImage(CameraImage cameraImage) {
final width = cameraImage.width;
final height = cameraImage.height;
final plane = cameraImage.planes[0];
final bytes = plane.bytes;
final bytesPerRow = plane.bytesPerRow;
// 手动创建空图，避免fromBytes的坑
final image = imglib.Image(width: width, height: height);
// 逐行、逐像素解析，严格按照相机流的 bytesPerRow 来读取，不会错位
for (int y = 0; y < height; y++) {
// 计算当前行的起始位置，严格按 bytesPerRow 偏移
final rowStart = y * bytesPerRow;
for (int x = 0; x < width; x++) {
// BGRA8888 每个像素占4字节，计算当前像素在该行的位置
final pixelOffset = x * 4;
final index = rowStart + pixelOffset;
// 防止越界
if (index + 3 >= bytes.length) continue;
// BGRA 格式顺序：B、G、R、A
final int b = bytes[index];
final int g = bytes[index + 1];
final int r = bytes[index + 2];
// 直接写入RGB，不依赖任何自动转换
image.setPixelRgb(x, y, r, g, b);
}
}
// 移除所有硬编码旋转，iOS相机流不需要这个，否则会导致画面错位
return image;
}
/// 原YUV逻辑保持不变（如果你Android也有问题，我可以再优化）
static imglib.Image convertYUV420ToImage(CameraImage cameraImage) {
final imageWidth = cameraImage.width;
final imageHeight = cameraImage.height;
final yBuffer = cameraImage.planes[0].bytes;
final uBuffer = cameraImage.planes[1].bytes;
final vBuffer = cameraImage.planes[2].bytes;
final int yRowStride = cameraImage.planes[0].bytesPerRow;
final int yPixelStride = cameraImage.planes[0].bytesPerPixel!;
final int uvRowStride = cameraImage.planes[1].bytesPerRow;
final int uvPixelStride = cameraImage.planes[1].bytesPerPixel!;
final image = imglib.Image(width: imageWidth, height: imageHeight);
for (int h = 0; h < imageHeight; h++) {
int uvh = (h / 2).floor();
for (int w = 0; w < imageWidth; w++) {
int uvw = (w / 2).floor();
final yIndex = (h * yRowStride) + (w * yPixelStride);
final int y = yBuffer[yIndex];
final int uvIndex = (uvh * uvRowStride) + (uvw * uvPixelStride);
final int u = uBuffer[uvIndex];
final int v = vBuffer[uvIndex];
int r = (y + v * 1436 / 1024 - 179).round();
int g = (y - u * 46549 / 131072 + 44 - v * 93604 / 131072 + 91).round();
int b = (y + u * 1814 / 1024 - 227).round();
r = r.clamp(0, 255);
g = g.clamp(0, 255);
b = b.clamp(0, 255);
image.setPixelRgb(w, h, r, g, b);
}
}
// 如果你Android也有随机偏色，把下面这行也注释掉
return imglib.copyRotate(image, angle: 270);
}
}

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flutter相机流ImageStream取图片偏蓝色绿红篮紫各种随机偏色BGRA8888,YUV420

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