C语言怎么读取bmp图片并通过位运算和数组进行处理
时间: 2024-02-06 07:12:59 浏览: 24
首先,我们需要读取BMP文件并将像素数据存储在一个数组中。这可以通过以下函数实现:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#pragma pack(push, 1)
typedef struct {
unsigned short bfType;
unsigned int bfSize;
unsigned short bfReserved1;
unsigned short bfReserved2;
unsigned int bfOffBits;
} BMPFileHeader;
typedef struct {
unsigned int biSize;
int biWidth;
int biHeight;
unsigned short biPlanes;
unsigned short biBitCount;
unsigned int biCompression;
unsigned int biSizeImage;
int biXPelsPerMeter;
int biYPelsPerMeter;
unsigned int biClrUsed;
unsigned int biClrImportant;
} BMPInfoHeader;
#pragma pack(pop)
unsigned char* load_bmp(const char* filename, int* width, int* height, int* channels)
{
FILE* file = fopen(filename, "rb");
if (!file) {
printf("Failed to open file \"%s\"\n", filename);
return NULL;
}
BMPFileHeader file_header;
BMPInfoHeader info_header;
fread(&file_header, sizeof(file_header), 1, file);
fread(&info_header, sizeof(info_header), 1, file);
*width = info_header.biWidth;
*height = info_header.biHeight;
*channels = info_header.biBitCount / 8;
int row_size = (*width) * (*channels);
if (row_size % 4 != 0) {
row_size += 4 - row_size % 4;
}
unsigned char* data = (unsigned char*)malloc(row_size * (*height));
fseek(file, file_header.bfOffBits, SEEK_SET);
fread(data, 1, row_size * (*height), file);
fclose(file);
return data;
}
```
以上函数会读取BMP文件的文件头和信息头,并将像素数据存储在一个数组中。注意,由于每行像素数据需要按照4字节对齐,所以我们需要根据像素通道数计算出每行像素数据的字节数,并在读取像素数据时跳过填充字节。
接下来,我们可以写一个函数来对像素数据进行位运算处理:
```c
void process_image(unsigned char* data, int width, int height, int channels)
{
int row_size = width * channels;
for (int y = 0; y < height; ++y) {
unsigned char* row = &data[y * row_size];
for (int x = 0; x < row_size; ++x) {
row[x] = ~row[x]; // 对每个像素进行按位取反操作
}
}
}
```
以上函数会对每个像素进行按位取反操作。你可以根据自己的需求编写其他的位运算操作。
最后,我们可以在主函数中调用以上函数来处理图像:
```c
int main()
{
int width, height, channels;
unsigned char* data = load_bmp("test.bmp", &width, &height, &channels);
process_image(data, width, height, channels);
write_bmp("output.bmp", data, width, height, channels);
free(data);
return 0;
}
```
在主函数中,我们先调用load_bmp函数读取BMP文件并获得像素数据,然后调用process_image函数对像素数据进行处理,最后调用write_bmp函数将处理后的像素数据保存为BMP文件。