OPENCV对图像解码并转制为RGB-NCWH格式

OpenCV Native 开发环境搭建步骤请参考：

OpenCV Native开发环境搭建_tugouxp的专栏-优快云博客

YOLOV3网络吃图格式为416*416 NCWH 三通道的RGB格式图，下面的程序可以将一张JPEG图像转换为对应的格式，基于OPENCV

#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>
#include <unistd.h>
 
using namespace std;
using namespace cv;
 
int main(int argc, char **argv)
{
	Mat img = imread("output_416x416.jpg");
	
	if(img.empty())
	{
		cout <<"please confirm the name of pic is right!" <<endl;
		return -1;
	}
 
	Mat imgs0, imgs1, imgs2;
	Mat imgv0, imgv1, imgv2;
	Mat result0, result1, result2;
	Mat imgs[3];
	split(img, imgs);
	imgs0 = imgs[0];
	imgs1 = imgs[1];
	imgs2 = imgs[2];
 
	printf("rows %d, cols %d, channel %d, type %d.\n", img.rows, img.cols, img.channels(), img.type());
	imshow("RGB-B", imgs0);
	imshow("RGB-G", imgs1);
	imshow("RGB-R", imgs2);
	printf("rows %d, cols %d, channel %d, type %d.\n", imgs0.rows, imgs0.cols, imgs0.channels(), imgs0.type());
	printf("rows %d, cols %d, channel %d, type %d.\n", imgs1.rows, imgs1.cols, imgs1.channels(), imgs1.type());
	printf("rows %d, cols %d, channel %d, type %d.\n", imgs2.rows, imgs2.cols, imgs2.channels(), imgs2.type());
 
	Mat zero = cv::Mat::zeros(img.rows, img.cols, CV_8UC1);
	imgs[0] = zero;
	imgs[2] = zero;
 
	merge(imgs, 3, result1);
	imshow("result1", result1);
 
	FILE *file = fopen("network_input.bin", "wb+");
	if(file == NULL)
	{
		cout << "fatal error,create file failure" << endl;
		exit(-1);
	}
 
	cv::MatIterator_<uchar> it0 = imgs0.begin<uchar>();
	cv::MatIterator_<uchar> it0_end = imgs0.end<uchar>();
	for (int i = 0; it0 != it0_end; it0 ++, i ++)
	{
		unsigned char data = *it0;
		int count = fwrite(&data, 1, 1, file);
		if(count != 1)
		{
			cout << "write binary failure." << endl;
		}
	}
 
	cv::MatIterator_<uchar> it1 = imgs1.begin<uchar>();
	cv::MatIterator_<uchar> it1_end = imgs1.end<uchar>();
	for (int i = 0; it1 != it1_end; it1 ++, i ++)
	{
		unsigned char data = *it1;
		int count = fwrite(&data, 1, 1, file);
		if(count != 1)
		{
			cout << "write binary failure." << endl;
		}
	}
 
	cv::MatIterator_<uchar> it2 = imgs2.begin<uchar>();
	cv::MatIterator_<uchar> it2_end = imgs2.end<uchar>();
	for (int i = 0; it2 != it2_end; it2 ++, i ++)
	{
		unsigned char data = *it2;
		int count = fwrite(&data, 1, 1, file);
		if(count != 1)
		{
			cout << "write binary failure." << endl;
		}
	}
 
	fsync(fileno(file));
	fflush(file);
	fclose(file);
 
	waitKey(0);
	return 0;
}

加上scale操作

scale 为416*416大小

#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>
#include <unistd.h>
 
using namespace std;
using namespace cv;

static void print_type(void)
{
	printf("CV_8UC1=%d.\n", CV_8UC1);
	printf("CV_8UC2=%d.\n", CV_8UC2);
	printf("CV_8UC3=%d.\n", CV_8UC3);
	printf("CV_8UC4=%d.\n", CV_8UC4);

	printf("CV_8SC1=%d.\n", CV_8SC1);
	printf("CV_8SC2=%d.\n", CV_8SC2);
	printf("CV_8SC3=%d.\n", CV_8SC3);
	printf("CV_8SC4=%d.\n", CV_8SC4);

	printf("CV_16UC1=%d.\n", CV_16UC1);
	printf("CV_16UC2=%d.\n", CV_16UC2);
	printf("CV_16UC3=%d.\n", CV_16UC3);
	printf("CV_16UC4=%d.\n", CV_16UC4);

	printf("CV_16SC1=%d.\n", CV_16SC1);
	printf("CV_16SC2=%d.\n", CV_16SC2);
	printf("CV_16SC3=%d.\n", CV_16SC3);
	printf("CV_16SC4=%d.\n", CV_16SC4);

	printf("CV_32SC1=%d.\n", CV_32SC1);
	printf("CV_32SC2=%d.\n", CV_32SC2);
	printf("CV_32SC3=%d.\n", CV_32SC3);
	printf("CV_32SC4=%d.\n", CV_32SC4);

	printf("CV_32FC1=%d.\n", CV_32FC1);
	printf("CV_32FC2=%d.\n", CV_32FC2);
	printf("CV_32FC3=%d.\n", CV_32FC3);
	printf("CV_32FC4=%d.\n", CV_32FC4);

	printf("CV_64FC1=%d.\n", CV_64FC1);
	printf("CV_64FC2=%d.\n", CV_64FC2);
	printf("CV_64FC3=%d.\n", CV_64FC3);
	printf("CV_64FC4=%d.\n", CV_64FC4);

	return;
}
 
int main(int argc, char **argv)
{
	print_type();
	Mat img = imread("dog.jpg");
	
	if(img.empty())
	{
		cout <<"please confirm the name of pic is right!" <<endl;
		return -1;
	}

	Size dsize = Size(416, 416);
	Mat img2 = Mat(dsize, CV_8UC3);

	resize(img, img2, dsize);
	imwrite("./scale.jpg",img2);

	printf("%s line %d, img2.type = %d, %d, %d.\n", __func__, __LINE__, img2.type(), CV_8UC1, CV_8UC3);
	//printf("%s line %d, img.type  = %d.\n", __func__, __LINE__, img.type());
 
	Mat imgs0, imgs1, imgs2;
	Mat result0, result1, result2;
	Mat imgs[3];
	split(img2, imgs);
	imgs0 = imgs[0];
	imgs1 = imgs[1];
	imgs2 = imgs[2];
 
	imshow("RGB-B", imgs0);
	imshow("RGB-G", imgs1);
	imshow("RGB-R", imgs2);

	printf("rows %d, cols %d, channel %d, type %d.\n", img2.rows, img2.cols, img2.channels(), img2.type());
	printf("rows %d, cols %d, channel %d, type %d.\n", imgs0.rows, imgs0.cols, imgs0.channels(), imgs0.type());
	printf("rows %d, cols %d, channel %d, type %d.\n", imgs1.rows, imgs1.cols, imgs1.channels(), imgs1.type());
	printf("rows %d, cols %d, channel %d, type %d.\n", imgs2.rows, imgs2.cols, imgs2.channels(), imgs2.type());
 
	Mat zero = cv::Mat::zeros(img2.rows, img2.cols, CV_8UC1);
	imgs[0] = zero;
	imgs[2] = zero;
 
	merge(imgs, 3, result1);
	imshow("result1", result1);
 
	FILE *file = fopen("network_input.bin", "wb+");
	if(file == NULL)
	{
		cout << "fatal error,create file failure" << endl;
		exit(-1);
	}
 
	cv::MatIterator_<uchar> it0 = imgs0.begin<uchar>();
	cv::MatIterator_<uchar> it0_end = imgs0.end<uchar>();
	for (int i = 0; it0 != it0_end; it0 ++, i ++)
	{
		unsigned char data = *it0;
		int count = fwrite(&data, 1, 1, file);
		if(count != 1)
		{
			cout << "write binary failure." << endl;
		}
	}
 
	cv::MatIterator_<uchar> it1 = imgs1.begin<uchar>();
	cv::MatIterator_<uchar> it1_end = imgs1.end<uchar>();
	for (int i = 0; it1 != it1_end; it1 ++, i ++)
	{
		unsigned char data = *it1;
		int count = fwrite(&data, 1, 1, file);
		if(count != 1)
		{
			cout << "write binary failure." << endl;
		}
	}
 
	cv::MatIterator_<uchar> it2 = imgs2.begin<uchar>();
	cv::MatIterator_<uchar> it2_end = imgs2.end<uchar>();
	for (int i = 0; it2 != it2_end; it2 ++, i ++)
	{
		unsigned char data = *it2;
		int count = fwrite(&data, 1, 1, file);
		if(count != 1)
		{
			cout << "write binary failure." << endl;
		}
	}
 
	fsync(fileno(file));
	fflush(file);
	fclose(file);
 
	waitKey(0);
	return 0;
}

scale.jpg文件是缩放后的图像,network_input.bin即是符合VIP YOLOV3网络的 RGB NCHW格式的数据输出，可以直接喂给网络进行推理。

纯C版的矩阵转置：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stddef.h>
#include <stdint.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
 
#define DBG(fmt, ...)   do { printf("%s line %d, "fmt"\n", __func__, __LINE__, ##__VA_ARGS__); } while (0)
 
static void dump_memory(uint8_t *buf, int32_t len)
{
    int i;
 
    printf("\n\rdump file memory:");
    for (i = 0; i < len; i ++)
    {
        if ((i % 16) == 0)
        {
            printf("\n\r%p: ", buf + i);
        }
        printf("0x%02x ", buf[i]);
    }
    printf("\n\r");
    return;
}
 
static double uint8_to_fp32(uint8_t val, int32_t zeropoint, double scale)
{
    double result = 0.0f;
 
    result = (val - (uint8_t)zeropoint) * scale;
 
    return result;
}
 
int main(int argc, char **argv)
{
	FILE *file;
	double scale;
	int zeropoint;
 
	DBG("in");
 
 
	file = fopen(argv[1], "rb");
	if(file == NULL)
	{
		DBG("fatal error, open file %s failure, please check the file status.", argv[1]);
		exit(-1);
	}
 
	fseek(file, 0, SEEK_END);
	int filelen = ftell(file);
	
	DBG("file %s len %d byets.", argv[1], filelen);
 
	unsigned char *p = malloc(filelen);
	if(p == NULL)
	{
		DBG("malloc buffer failure for %s len %d.", argv[1], filelen);
		exit(-1);
	}
 
	memset(p, 0x00, filelen);
	fseek(file, 0, SEEK_SET);
 
	if(fread(p, 1, filelen, file) != filelen)
	{
		DBG("read file failure, size wrong.");
		exit(-1);
	}
 
	char outputname[255];
	memset(outputname, 0x00, 255);
	memcpy(outputname, argv[1], strlen(argv[1]));
	memcpy(outputname+strlen(argv[1]), ".rgb", 7);
	DBG("output tensor name %s", outputname);
 
	FILE *outensor = fopen(outputname, "wb+");
	if(outensor == NULL)
	{
		DBG("fatal error, create output tensor file %s failure, please check the file status.", outputname);
		exit(-1);
	}
 
	dump_memory(p, 32);

	unsigned char *w = malloc(filelen);
	if(w == NULL)
	{
		DBG("malloc buffer failure for %s len %d.", argv[1], filelen);
		exit(-1);
	}
 
	memset(w, 0x00, filelen);

	int i, j, k;

	for(i = 0; i < 3; i ++)
	{
		for(j = 0; j < 416; j ++)
		{
			for(k = 0; k < 416; k ++)
			{
				//w[i][j][k] = p[j][k][i];
				//w[i*416 * 416 + j*416 + k] = p[j*416*3 + k*3 + i];
				w[(2-i)*416 * 416 + j*416 + k] = p[j*416*3 + k*3 + i];
			}
		}
	}

	if(fwrite(w, 1, filelen, outensor) != filelen)
	{
		DBG("write file failure, size wrong.");
		exit(-1);
	}
 
	fflush(outensor);
	fsync(fileno(outensor));
 
	fclose(outensor);
	fclose(file);
	free(p);
	DBG("out");
	return 0;
}

参考博客

转置算子(transpose)的一种实现_papaofdoudou的博客-优快云博客_transpose算子

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结束！