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cuda入门demo（2）——最基础的二方向sobel

news 2025/7/4 9:09:09

⚠️主要是自己温习用，只保证代码正确性，不保证讲解的详细性。

今天继续总结cuda最基本的入门demo。很多教程会给你说conv怎么写，实际上sobel也是conv，并且conv本身已经用torch实现了。

之前在课题中尝试了sobel的变体，为了起一个复习的作用，我把原始sobel（不是变体）的代码备份到这里，比起变体，这个原始的非常简单，很适合学习。

最简单的sobel

#include <opencv2/opencv.hpp>
#include <iostream>
#include <cuda_runtime.h>
#include <device_launch_parameters.h>using namespace std;
using namespace cv;__global__ void sobel_gpu(unsigned char* in, unsigned char* out, const int Height, const int Width) {int x = blockDim.y * blockIdx.y + threadIdx.y;int y = blockDim.x * blockIdx.x + threadIdx.x;// 只对非边缘地带进行计算if (x > 0 && x < Height - 1 && y > 0 && y < Width - 1) {int idx = x * Width + y;int idx_up = idx - Width;int idx_down = idx + Width;char gx_res = in[idx_up - 1] + 2 * in[idx - 1] + in[idx_down - 1] - in[idx_up + 1] - 2 * in[idx + 1] - in[idx_down + 1];char gy_res = in[idx_up - 1] + 2 * in[idx_up] + in[idx_up + 1] - in[idx_down - 1] - 2 * in[idx_down] - in[idx_down + 1];out[idx] = (gx_res + gy_res) / 2;}else if (x == 0 || x == Height - 1 || y == 0 || y == Width - 1) {int idx = x * Width + y;out[idx] = in[idx];}
}int main() {Mat img = imread("lena.jpg", 0);int height = img.rows;int width = img.cols;int memsize = height * width * sizeof(unsigned char);Mat gaussImg;GaussianBlur(img, gaussImg, Size(3, 3), 0, 0, BORDER_DEFAULT);Mat dst_gpu(height, width, CV_8UC1, Scalar(0));unsigned char* in_gpu;unsigned char* out_gpu;// 接下来对模糊之后的图像进行处理cudaMalloc((void**)&in_gpu, memsize);cudaMalloc((void**)&out_gpu, memsize);dim3 threadsPerBlock(32, 32);dim3 blocksPerGrid((width + threadsPerBlock.x - 1) / threadsPerBlock.x, (height + threadsPerBlock.y - 1) / threadsPerBlock.y);cudaMemcpy(in_gpu, gaussImg.data, memsize, cudaMemcpyHostToDevice);sobel_gpu << < blocksPerGrid, threadsPerBlock > >> (in_gpu, out_gpu, height, width);cudaMemcpy(dst_gpu.data, out_gpu, memsize, cudaMemcpyDeviceToHost);imwrite("save.png", dst_gpu);cudaFree(in_gpu);cudaFree(out_gpu);return 0;
}