用c语言写一段对图片进行灰度处理的代码

好的，以下是示例代码：

#include <stdio.h>

int main() {
   FILE *fp;
   char buf[54];
   int width, height, rawSize;
   unsigned char *rawData;
   
   // Open image file
   fp = fopen("image.bmp", "rb");
   if (!fp) {
      printf("Error: Failed to open image file!\n");
      return 1;
   }
   
   // Read BMP header
   fread(buf, sizeof(char), 54, fp);
   width = *(int*)&buf[18];
   height = *(int*)&buf[22];
   rawSize = *(int*)&buf[34];
   
   // Allocate memory for raw data
   rawData = (unsigned char*)malloc(rawSize);
   
   // Read raw data
   fread(rawData, sizeof(unsigned char), rawSize, fp);
   
   // Close image file
   fclose(fp);
   
   // Convert to grayscale
   for (int i = 0; i < rawSize; i += 3) {
      unsigned char gray = (unsigned char)(0.299 * rawData[i+2] + 0.587 * rawData[i+1] + 0.114 * rawData[i]);
      rawData[i+2] = rawData[i+1] = rawData[i] = gray;
   }
   
   // Open output image file
   fp = fopen("grayscale.bmp", "wb");
   if (!fp) {
      printf("Error: Failed to create output image file!\n");
      return 1;
   }
   
   // Write BMP header and raw data
   fwrite(buf, sizeof(char), 54, fp);
   fwrite(rawData, sizeof(unsigned char), rawSize, fp);
   
   // Close output image file
   fclose(fp);
   
   // Free memory
   free(rawData);
   
   printf("Grayscale conversion completed!\n");
   
   return 0;
}

该代码使用了 BMP 文件格式来存储图像数据，并且只能处理 24 位彩色位图。将 RGB 三个颜色通道按比例加权求和即可转换为灰度值。