以ppm格式编辑图像

Question

我正在尝试通过将每个像素的红色分量乘以10来编辑图像，并保持其他组件（绿色和蓝色）不变。我不确定我应该如何逐个编辑像素。到目前为止我有这个。我认为我的ppm标题也有问题。有没有办法在不指定边界的情况下制作ppm标题，以使其符合您放入的图像？

#include <stdlib.h>
#include <stdio.h>
#define PICTURE_FILE 1
#define MIN_ARGS 2
#define h 768
#define w 1024

void solve(FILE *in_picture, FILE *out_picture)
{
    printf("P3  1024 768 255\n");
    double r, g, b, row, col;
    int ret = fscanf(in_picture, "%lf %lf %lf ", &r, &g, &b);
    while(ret != EOF)
    {
        for(row=1; row <= h; row++) 
        {
            for(col=1; col <= w; col++)
            {
                fprintf(out_picture, "%lf %lf %lf ", r*10 , g, b);
            }
        ret = fscanf(in_picture, "%lf %lf %lf ", &r, &g, &b);
        }
    }
}

FILE *open_file(const char name[], const char mode[])
{
    FILE *file = fopen(name, mode);
    if(file == NULL)
    {
        perror(name);
    exit(1);
    }
    return file;
}

void check_args(int argc, char *argv[])
{
    if(argc < MIN_ARGS)
    {
        fprintf(stderr, "%s: not enough arguments \n", argv[0]);
    exit(1);
    }
}

int main(int argc, char *argv[])
{
    check_args(argc, argv);
    FILE *in_picture = open_file(argv[PICTURE_FILE], "r");
    FILE *out_picture = open_file("hidden.ppm", "w");

    solve(in_picture, out_picture);
    fclose(in_picture);
    fclose(out_picture);

}