tensorflow lite使用ssd_keras进行图片物体检测

使用的是这个工程 pierluigiferrari/ssd_keras

1.数据集标注

a.采用VoTT用于图像检测任务的数据集制作voc格式

2.模型训练

使用这个文件里面https://github.com/pierluigiferrari/ssd_keras/blob/master/ssd300_training.ipynb加载voc格式数据集的方法
利用这个https://github.com/pierluigiferrari/ssd_keras/blob/master/ssd7_training.ipynb训练一个浅层的深度学习模型,这个模型部署到ncnn有若干层不支持
由于我利用vott制作的数据集中有些属性缺少,加载数据集时会出错,需要对文件data_generator/object_detection_2d_data_generator.py作出如下修改,
difficult = int(obj.difficult.text) 修改为 difficult = 0
if batch_inverse_transforms: batch_inverse_transforms.pop(j)修改为
if batch_inverse_transforms and j < len(batch_inverse_transforms): batch_inverse_transforms.pop(j)
我在标注数据集的时候有些出错,在这里修改以下

                    for obj in objects:
                        print(filename)
                        class_name = obj.find('name').text
                        class_name = class_name.lower()
                        if class_name == 'thanks-1':
                           class_name = 'thanks' 
                        class_id = self.classes.index(class_name)

3.利用tensorflow lite布置到移动端

a.The TensorFlow Lite iOS Demo App,使用量化模型实时预测

上面的demo如果要使用非量化模型需要做如下改动

// If you have your own model, modify this to the file name, and make sure
// you've added the file to your app resources too.
//static NSString* model_file_name = @"mobilenet_quant_v1_224";
static NSString* model_file_name = @"mobilenet_v1_1.0_224";
static NSString* model_file_type = @"tflite";
// Returns the top N confidence values over threshold in the provided vector,
// sorted by confidence in descending order.
static void GetTopN_float(const float* prediction, const int prediction_size, const int num_results,
                    const float threshold, std::vector>* top_results) {
    // Will contain top N results in ascending order.
    std::priority_queue, std::vector>,
    std::greater>>
    top_result_pq;

    const long count = prediction_size;
    for (int i = 0; i < count; ++i) {
        const float value = prediction[i];//#######不用除以255.0
        // Only add it if it beats the threshold and has a chance at being in
        // the top N.
        if (value < threshold) {
            continue;
        }
        
        top_result_pq.push(std::pair(value, i));
        
        // If at capacity, kick the smallest value out.
        if (top_result_pq.size() > num_results) {
            top_result_pq.pop();
        }
    }
    
    // Copy to output vector and reverse into descending order.
    while (!top_result_pq.empty()) {
        top_results->push_back(top_result_pq.top());
        top_result_pq.pop();
    }
    std::reverse(top_results->begin(), top_results->end());
}
//注意如果相机是默认设置的话,pixelBuffer得到的图片是横着的
- (void)runModelOnFrame_float:(CVPixelBufferRef)pixelBuffer {
    assert(pixelBuffer != NULL);
    
    OSType sourcePixelFormat = CVPixelBufferGetPixelFormatType(pixelBuffer);
    assert(sourcePixelFormat == kCVPixelFormatType_32ARGB ||
           sourcePixelFormat == kCVPixelFormatType_32BGRA);
    
    const int sourceRowBytes = (int)CVPixelBufferGetBytesPerRow(pixelBuffer);
    const int image_width = (int)CVPixelBufferGetWidth(pixelBuffer);
    const int fullHeight = (int)CVPixelBufferGetHeight(pixelBuffer);
    
    CVPixelBufferLockFlags unlockFlags = kNilOptions;
    CVPixelBufferLockBaseAddress(pixelBuffer, unlockFlags);
    
    unsigned char* sourceBaseAddr = (unsigned char*)(CVPixelBufferGetBaseAddress(pixelBuffer));
    int image_height;
    unsigned char* sourceStartAddr;
    if (fullHeight <= image_width) {
        image_height = fullHeight;
        sourceStartAddr = sourceBaseAddr;
    } else {
        image_height = image_width;
        const int marginY = ((fullHeight - image_width) / 2);
        sourceStartAddr = (sourceBaseAddr + (marginY * sourceRowBytes));
    }
    const int image_channels = 4;
    assert(image_channels >= wanted_input_channels);
    uint8_t* in = sourceStartAddr;
    //根据当前问题填充输入张量
    //得到输入张量数组中的第一个张量,也就是classifier中唯一的那个输入张量,input是个整型值,语义是张量列表中的引索。第二条语句有两个作用,
    //1)以input为索引,在TfLiteTensor* content_.tensors这个张量表得到具体的张量。
    int input = interpreter->inputs()[0];
    //2)返回该张量data.raw,它指示张量正关联着的内存块。有了out,app就把可以把要预测的图像数据填向它了。
    float* out = interpreter->typed_tensor(input);
    
    const float input_mean = 127.5f;
    const float input_std = 127.5f;
    for (int y = 0; y < wanted_input_height; ++y) {
        float* out_row = out + (y * wanted_input_width * wanted_input_channels);
        for (int x = 0; x < wanted_input_width; ++x) {
            const int in_x = (y * image_width) / wanted_input_width;
            const int in_y = (x * image_height) / wanted_input_height;
            uint8_t* in_pixel = in + (in_y * image_width * image_channels) + (in_x * image_channels);
            float* out_pixel = out_row + (x * wanted_input_channels);
            for (int c = 0; c < wanted_input_channels; ++c) {
               //#############归一化
                out_pixel[c] = (in_pixel[c] - input_mean) / input_std;
            }
        }
    }
    //调用Invoke进行预测
    double startTimestamp = [[NSDate new] timeIntervalSince1970];
    if (interpreter->Invoke() != kTfLiteOk) {
        LOG(FATAL) << "Failed to invoke!";
    }
    double endTimestamp = [[NSDate new] timeIntervalSince1970];
    total_latency += (endTimestamp - startTimestamp);
    total_count += 1;
    NSLog(@"Time: %.4lf, avg: %.4lf, count: %d", endTimestamp - startTimestamp,
          total_latency / total_count, total_count);
    
    const int output_size = 1000;
    const int kNumResults = 5;
    const float kThreshold = 0.1f;
    
    std::vector> top_results;
    
    //解析输出张量得到识别结果
    //作用是得到输出张量关联的内存块。output存放的数据已是一维数组,之后就可用它得到识别结果了
    float* output = interpreter->typed_output_tensor(0);
    //GetTopN用于计算output数组中最大的N个值(first),以及它们的位置(second)
    GetTopN_float(output, output_size, kNumResults, kThreshold, &top_results);
    
    NSMutableDictionary* newValues = [NSMutableDictionary dictionary];
    for (const auto& result : top_results) {
        const float confidence = result.first;
        const int index = result.second;
        NSString* labelObject = [NSString stringWithUTF8String:labels[index].c_str()];
        NSNumber* valueObject = [NSNumber numberWithFloat:confidence];
        [newValues setObject:valueObject forKey:labelObject];
    }
    dispatch_async(dispatch_get_main_queue(), ^(void) {
        [self setPredictionValues:newValues];
    });
    
    CVPixelBufferUnlockBaseAddress(pixelBuffer, unlockFlags);
    
    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);
}

运行非量化模型预测图片
cd tensorflow/contrib/lite/examples/ios/simple
pod install
pod update
open tflite_simple_example.xcworkspace

demo的理解:
TensorFlow Lite(2/3):tflite文件和AI Smart

使用非压缩模型会奔溃,解决方案如下:
mobilenet_quant_v1_224.tflite. but crash when i run my own model and give the error
label_image.cc

tensorflow .pb文件模型量化

Fixed Point Quantization
Using 8-bit calculations help your models run faster and use less power.

b.生成TFLite文件,要先安装tensorflow源码和bazel方法,编译tensorflow源码生成tensorflow

Installing Bazel

从源代码安装 TensorFlow

bazel build --config=opt //tensorflow/tools/pip_package:build_pip_package
如果tensorflow环境已经搭建好的话,执行到上一步就可以了

如果build过程失败了,我们也可以执行如下指令,只生成我们在模型转化时需要的执行文件
.bazel build tensorflow/python/tools:freeze_graph
bazel build --config=opt tensorflow/contrib/lite/toco:toco
bazel build tensorflow/tools/graph_transforms:summarize_graph
bazel build tensorflow/tools/quantization:quantize_graph

Exporting the Inference Graph
Convert the model format
tensorflow保存pb文件

Tensorflow Lite之编译生成tflite文件
TensorFlow Lite学习笔记2:生成TFLite模型文件
TensorFlow Lite相关
如何量化现有的pb模型
bazel-bin/tensorflow/tools/quantization/quantize_graph --input=/home/ljg/下载/mobilenet_v1_1.0_224/mobilenet_v1_1.0_224_frozen.pb --output_node_names=MobilenetV1/Predictions/Reshape_1 --output=quantized_graph.pb --mode=eightbit

bazel-bin/tensorflow/contrib/lite/toco/toco --input_file=quantized_graph.pb --input_format=TENSORFLOW_GRAPHDEF --output_format=TFLITE --output_file=quantized_graphh.tflite --inference_type=QUANTIZED_UINT8 --inference_input_type=QUANTIZED_UINT8 --input_shapes=1,224,224,3 --input_arrays=input --output_arrays=MobilenetV1/Predictions/Reshape_1 --mean_values=128 --std_values=128 --default_ranges_min=0 --default_ranges_max=6

tensorflow lite: error when convert frozen model to lite format

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