ANSCORE/modules/ANSOCR/ANSONNXOCR/ONNXOCRRecognizer.cpp

#include "ONNXOCRRecognizer.h"

#include <opencv2/imgproc.hpp>
#include <iostream>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <cfloat>
#include <cstring>

namespace ANSCENTER {
namespace onnxocr {

ONNXOCRRecognizer::ONNXOCRRecognizer(const std::string& onnx_path, unsigned int num_threads)
    : BasicOrtHandler(onnx_path, num_threads) {
}

bool ONNXOCRRecognizer::LoadDictionary(const std::string& dictPath) {
    keys_ = LoadDict(dictPath);
    if (keys_.size() < 2) {
        std::cerr << "[ONNXOCRRecognizer] Failed to load dictionary: " << dictPath << std::endl;
        return false;
    }
    std::cout << "[ONNXOCRRecognizer] Loaded dictionary with " << keys_.size()
              << " characters from: " << dictPath << std::endl;
    return true;
}

Ort::Value ONNXOCRRecognizer::transform(const cv::Mat& mat) {
    // Not used directly - recognition uses custom preprocess with dynamic width
    cv::Mat resized = ResizeRecImage(mat, imgH_, imgMaxW_);
    resized.convertTo(resized, CV_32FC3);
    auto data = NormalizeAndPermuteCls(resized);

    input_values_handler.assign(data.begin(), data.end());
    return Ort::Value::CreateTensor<float>(
        *memory_info_handler, input_values_handler.data(), input_values_handler.size(),
        input_node_dims.data(), input_node_dims.size());
}

Ort::Value ONNXOCRRecognizer::transformBatch(const std::vector<cv::Mat>& images) {
    // Not used - recognizer processes single images with dynamic widths
    if (!images.empty()) {
        return transform(images[0]);
    }
    return Ort::Value(nullptr);
}

TextLine ONNXOCRRecognizer::Recognize(const cv::Mat& croppedImage) {
    std::lock_guard<std::mutex> lock(_mutex);

    if (!ort_session || croppedImage.empty() || keys_.empty()) {
        return {};
    }

    try {
        // Preprocess: resize to fixed height, proportional width
        cv::Mat resized = ResizeRecImage(croppedImage, imgH_, imgMaxW_);
        int resizedW = resized.cols;

        resized.convertTo(resized, CV_32FC3);
        // Recognition uses (pixel/255 - 0.5) / 0.5 normalization (same as classifier)
        auto normalizedData = NormalizeAndPermuteCls(resized);

        // Pad to at least kRecImgW width (matching official PaddleOCR behavior)
        // Official PaddleOCR: padding_im = np.zeros((C, H, W)), then copies normalized
        // image into left portion. Padding value = 0.0 in normalized space.
        int imgW = std::max(resizedW, kRecImgW);

        std::vector<float> inputData;
        if (imgW > resizedW) {
            // Zero-pad on the right (CHW layout)
            inputData.resize(3 * imgH_ * imgW, 0.0f);
            for (int c = 0; c < 3; c++) {
                for (int y = 0; y < imgH_; y++) {
                    std::memcpy(
                        &inputData[c * imgH_ * imgW + y * imgW],
                        &normalizedData[c * imgH_ * resizedW + y * resizedW],
                        resizedW * sizeof(float));
                }
            }
        } else {
            inputData = std::move(normalizedData);
        }

        // Create input tensor with (possibly padded) width
        std::array<int64_t, 4> inputShape = { 1, 3, imgH_, imgW };
        Ort::Value inputTensor = Ort::Value::CreateTensor<float>(
            *memory_info_handler, inputData.data(), inputData.size(),
            inputShape.data(), inputShape.size());

        // Run inference
        auto outputTensors = ort_session->Run(
            Ort::RunOptions{ nullptr },
            input_node_names.data(), &inputTensor, 1,
            output_node_names.data(), num_outputs);

        // Get output
        float* outputData = outputTensors[0].GetTensorMutableData<float>();
        auto outputShape = outputTensors[0].GetTensorTypeAndShapeInfo().GetShape();

        int seqLen = static_cast<int>(outputShape[1]);
        int numClasses = static_cast<int>(outputShape[2]);

        return CTCDecode(outputData, seqLen, numClasses);
    }
    catch (const Ort::Exception& e) {
        std::cerr << "[ONNXOCRRecognizer] Inference failed: " << e.what() << std::endl;
        return {};
    }
}

std::vector<TextLine> ONNXOCRRecognizer::RecognizeBatch(const std::vector<cv::Mat>& croppedImages) {
    std::vector<TextLine> results;
    results.reserve(croppedImages.size());

    // Process one at a time (dynamic width per image)
    for (size_t i = 0; i < croppedImages.size(); i++) {
        results.push_back(Recognize(croppedImages[i]));
    }

    return results;
}

TextLine ONNXOCRRecognizer::CTCDecode(const float* outputData, int seqLen, int numClasses) {
    TextLine result;
    std::string text;
    std::vector<float> scores;

    int lastIndex = 0; // CTC blank is index 0

    for (int t = 0; t < seqLen; t++) {
        // Find argmax for this timestep
        int maxIndex = 0;
        float maxValue = -FLT_MAX;

        const float* timeStep = outputData + t * numClasses;
        for (int c = 0; c < numClasses; c++) {
            if (timeStep[c] > maxValue) {
                maxValue = timeStep[c];
                maxIndex = c;
            }
        }

        // CTC decode: skip blanks (index 0) and repeated characters
        if (maxIndex != 0 && maxIndex != lastIndex) {
            if (maxIndex > 0 && maxIndex < static_cast<int>(keys_.size())) {
                text += keys_[maxIndex]; // keys_[0]="#"(blank), keys_[1]=first_char, etc.
                // Use raw model output value as confidence (PaddleOCR v5 models include softmax)
                scores.push_back(maxValue);
            }
        }
        lastIndex = maxIndex;
    }

    result.text = text;
    if (!scores.empty()) {
        result.score = std::accumulate(scores.begin(), scores.end(), 0.0f) /
                       static_cast<float>(scores.size());
    }
    return result;
}

} // namespace onnxocr
} // namespace ANSCENTER