image_to_pixle_params_yoloSAM/ultralytics-main/examples/YOLOv8-MNN-CPP/main_interpreter.cpp

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2025-07-14 17:36:53 +08:00
// Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license
#include <stdio.h>
#include <stdlib.h>
#include <vector>
#include <string>
#include <regex>
#include <MNN/ImageProcess.hpp>
#include <MNN/expr/Module.hpp>
#include <MNN/expr/Executor.hpp>
#include <MNN/expr/ExprCreator.hpp>
#include <cv/cv.hpp>
using namespace MNN;
using namespace MNN::Express;
using namespace MNN::CV;
class Inference {
public:
Inference() : interpreter(nullptr), session(nullptr), inputTensor(nullptr) {
inputDims = {1, 3, 640, 640};
}
~Inference() {
if(interpreter) {
delete interpreter;
interpreter = nullptr;
}
}
// Load model, create session, and resize the input tensor.
bool loadModel(const std::string &modelPath,
int forwardType = MNN_FORWARD_CPU,
int precision = 1,
int thread = 4) {
MNN::ScheduleConfig sConfig;
sConfig.type = static_cast<MNNForwardType>(forwardType);
sConfig.numThread = thread;
BackendConfig bConfig;
bConfig.precision = static_cast<BackendConfig::PrecisionMode>(precision);
sConfig.backendConfig = &bConfig;
interpreter = MNN::Interpreter::createFromFile(modelPath.c_str());
if (!interpreter) {
MNN_PRINT("Error: Failed to create interpreter from model file.\n");
return false;
}
session = interpreter->createSession(sConfig);
if(!session) {
MNN_PRINT("Error: Failed to create session.\n");
return false;
}
inputTensor = interpreter->getSessionInput(session, "images");
interpreter->resizeTensor(inputTensor, inputDims);
interpreter->resizeSession(session);
std::string bizCode = interpreter->bizCode();
// Get names from bizCode.
auto names_start = bizCode.find("\"names\": {");
if (names_start == std::string::npos) {
MNN_PRINT("No names found in bizCode, setting classNames empty.\n");
classNames.clear();
} else {
auto names_end = bizCode.find("}", names_start);
if (names_end == std::string::npos) {
MNN_PRINT("No closing brace for names in bizCode, setting classNames empty.\n");
classNames.clear();
} else {
std::string namesDict = bizCode.substr(names_start + 10, names_end - names_start - 10);
parseClassNamesFromBizCode(namesDict);
}
}
return true;
}
void parseClassNamesFromBizCode(const std::string& bizText) {
std::regex rgx("\"(\\d+)\"\\s*:\\s*\"([^\"]+)\"");
std::smatch match;
std::string s = bizText;
classNames.clear();
while (std::regex_search(s, match, rgx)) {
int index = std::stoi(match[1].str());
std::string name = match[2].str();
if (classNames.size() <= static_cast<size_t>(index)) {
classNames.resize(index + 1);
}
classNames[index] = name;
s = match.suffix().str();
}
}
VARP preprocess(VARP &originalImage, int targetSize, float &scale) {
const auto dims = originalImage->getInfo()->dim;
const int ih = dims[0], iw = dims[1];
const int len = (ih >= iw ? ih : iw);
scale = static_cast<float>(len) / targetSize;
// Use fixed-size array for padding values.
int padvals[6] = { 0, len - ih, 0, len - iw, 0, 0 };
auto pads = _Const(static_cast<void*>(padvals), {3, 2}, NCHW, halide_type_of<int>());
auto padded = _Pad(originalImage, pads, CONSTANT);
auto resized = MNN::CV::resize(padded, MNN::CV::Size(targetSize, targetSize),
0, 0, MNN::CV::INTER_LINEAR, -1,
{0.f, 0.f, 0.f},
{1.f/255, 1.f/255, 1.f/255});
// Chain unsqueeze and conversion
auto input = _Unsqueeze(resized, {0});
input = _Convert(input, NCHW);
return input;
}
// Run inference by copying preprocessed data into input tensor.
void runInference(VARP input) {
auto tmp_input = MNN::Tensor::create(inputDims, halide_type_of<float>(),
const_cast<void*>(input->readMap<void>()),
MNN::Tensor::CAFFE);
inputTensor->copyFromHostTensor(tmp_input);
interpreter->runSession(session);
}
// Postprocess the output, perform NMS, and draw bounding boxes on originalImage.
void postprocess(float scale, VARP originalImage, float modelScoreThreshold = 0.25, float modelNMSThreshold = 0.45) {
auto outputTensor = interpreter->getSessionOutput(session, "output0");
// ---------------- Post Processing ----------------
auto outputs = outputTensor->host<float>();
auto outputVar = _Const(outputs, outputTensor->shape(), NCHW, halide_type_of<float>());
auto output = _Squeeze(_Convert(outputVar, NCHW));
// Expected output shape: [84, 8400] where first 4 rows are [cx, cy, w, h].
auto cx = _Gather(output, _Scalar<int>(0));
auto cy = _Gather(output, _Scalar<int>(1));
auto w = _Gather(output, _Scalar<int>(2));
auto h = _Gather(output, _Scalar<int>(3));
// Slice probability values (starting at row 4).
const int startArr[2] = { 4, 0 };
const int sizeArr[2] = { -1, -1 };
auto start = _Const(static_cast<void*>(const_cast<int*>(startArr)), {2}, NCHW, halide_type_of<int>());
auto size = _Const(static_cast<void*>(const_cast<int*>(sizeArr)), {2}, NCHW, halide_type_of<int>());
auto probs = _Slice(output, start, size);
// Convert [cx, cy, w, h] to [y1, x1, y2, x2] using half-width/height.
auto half = _Const(0.5);
auto x1 = cx - w * half;
auto y1 = cy - h * half;
auto x2 = cx + w * half;
auto y2 = cy + h * half;
auto boxes = _Stack({x1, y1, x2, y2}, 1);
auto scores = _ReduceMax(probs, {0});
auto ids = _ArgMax(probs, 0);
auto result_ids = _Nms(boxes, scores, 100, modelScoreThreshold, modelNMSThreshold);
auto result_ptr = result_ids->readMap<int>();
auto box_ptr = boxes->readMap<float>();
auto ids_ptr = ids->readMap<int>();
auto score_ptr = scores->readMap<float>();
const int numResults = result_ids->getInfo()->size;
for (int i = 0; i < numResults; i++) {
int idx = result_ptr[i];
if (idx < 0) break;
float x1 = box_ptr[idx * 4 + 0] * scale;
float y1 = box_ptr[idx * 4 + 1] * scale;
float x2 = box_ptr[idx * 4 + 2] * scale;
float y2 = box_ptr[idx * 4 + 3] * scale;
int class_idx = ids_ptr[idx];
float score = score_ptr[idx];
printf("Detection: box = {%.2f, %.2f, %.2f, %.2f}, class = %s, score = %.2f\n",
x1, y1, x2, y2, classNames[class_idx].c_str(), score);
rectangle(originalImage, { x1, y1 }, { x2, y2 }, { 0, 255, 0 }, 2);
MNN::CV::rectangle(originalImage, { x1, y1 }, { x2, y2 }, { 0, 255, 0 }, 2);
// Note: MNN::CV does not offer a putText function.
// For text annotations, consider converting the image to cv::Mat and using OpenCV.
}
if (MNN::CV::imwrite("mnn_yolov8_cpp.jpg", originalImage)) {
MNN_PRINT("Result image written to `mnn_yolov8_cpp.jpg`.\n");
}
}
private:
MNN::Interpreter* interpreter;
MNN::Session* session;
MNN::Tensor* inputTensor;
std::vector<int> inputDims;
std::vector<std::string> classNames;
};
int main(int argc, const char* argv[]) {
if (argc < 3) {
MNN_PRINT("Usage: ./main yolov8n.mnn input.jpg [backend] [precision] [thread]\n");
return 0;
}
int backend = MNN_FORWARD_CPU;
int precision = 1;
int thread = 4;
if (argc >= 4) {
backend = atoi(argv[3]);
}
if (argc >= 5) {
precision = atoi(argv[4]);
}
if (argc >= 6) {
thread = atoi(argv[5]);
}
Inference infer;
if (!infer.loadModel(argv[1], backend, precision, thread))
return 1;
const clock_t begin_time = clock();
float scale = 1.0f;
VARP originalImage = imread(argv[2]);
VARP input = infer.preprocess(originalImage, 640, scale);
auto preprocess_time = 1000.0 * (clock() - begin_time) / CLOCKS_PER_SEC;
const clock_t begin_time2 = clock();
infer.runInference(input);
auto inference_time = 1000.0 * (clock() - begin_time2) / CLOCKS_PER_SEC;
const clock_t begin_time3 = clock();
infer.postprocess(scale, originalImage);
auto postprocess_time = 1000.0 * (clock() - begin_time3) / CLOCKS_PER_SEC;
printf("Speed: %.1fms preprocess, %.1fms inference, %.1fms postprocess\n",
preprocess_time, inference_time, postprocess_time);
return 0;
}