iOS Swift中如何获取CVBuffer的亮度/光强度？

以下是实现从CVBuffer中提取光强度的Swift代码，适用于iOS应用开发：

func fetchLightIntensity(from pixelBuffer: CVPixelBuffer) {
    CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly)
    
    if let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer) {
        let width = CVPixelBufferGetWidth(pixelBuffer)
        let height = CVPixelBufferGetHeight(pixelBuffer)
        let bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)
        
        let buffer = baseAddress.assumingMemoryBound(to: UInt8.self)
        
        var totalIntensity: UInt32 = 0
        
        for y in 0..<height {
            let row = buffer.advanced(by: y * bytesPerRow)
            
            for x in 0..<width {
                let pixel = row.advanced(by: x)
                let intensity = UInt32(pixel.pointee)
                totalIntensity += intensity
            }
        }
        
        let averageIntensity = totalIntensity / UInt32(width * height)
        
        // 转换为0-100范围的光强度值
        let rangeIntensity = (averageIntensity * 100) / 255
        
        // 将结果存入全局变量
        lightIntensity = rangeIntensity
        print("Light Intensity : \(self.lightIntensity)")
    }
    
    CVPixelBufferUnlockBaseAddress(pixelBuffer, .readOnly)
}

关键说明： #

• 操作CVBuffer前必须调用CVPixelBufferLockBaseAddress，操作完成后调用CVPixelBufferUnlockBaseAddress，保证缓冲区的访问安全
• 代码默认像素格式为单通道UInt8灰度图，如果你的CVBuffer是RGBA等多通道格式，需要修改像素读取逻辑（比如取RGB通道的平均值作为强度）
• 通过遍历所有像素计算总强度，再求平均值，最后转换为0-100的直观范围值
• 最终结果存入全局变量lightIntensity，可根据需求调整存储方式

内容的提问来源于stack exchange，提问作者Suleman Tariq