使用libpng读取有损失的PNG图片
时间: 2024-05-09 07:19:03 浏览: 8
1. 首先,需要安装libpng库,可以通过以下命令在Ubuntu上安装:
```
sudo apt-get install libpng-dev
```
2. 接下来,需要编写一个C程序来读取PNG图像。以下是一个简单的程序示例:
```c
#include <stdio.h>
#include <stdlib.h>
#include <png.h>
int main(int argc, char *argv[]) {
if (argc != 2) {
printf("Usage: %s <filename>\n", argv[0]);
return 1;
}
char *filename = argv[1];
FILE *fp = fopen(filename, "rb");
if (!fp) {
printf("Failed to open %s\n", filename);
return 1;
}
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr) {
printf("Failed to create PNG read struct\n");
fclose(fp);
return 1;
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
printf("Failed to create PNG info struct\n");
png_destroy_read_struct(&png_ptr, NULL, NULL);
fclose(fp);
return 1;
}
png_init_io(png_ptr, fp);
png_read_info(png_ptr, info_ptr);
int width = png_get_image_width(png_ptr, info_ptr);
int height = png_get_image_height(png_ptr, info_ptr);
png_byte color_type = png_get_color_type(png_ptr, info_ptr);
png_byte bit_depth = png_get_bit_depth(png_ptr, info_ptr);
printf("Image size: %d x %d\n", width, height);
printf("Color type: %d\n", color_type);
printf("Bit depth: %d\n", bit_depth);
png_bytep row_pointers[height];
for (int y = 0; y < height; y++) {
row_pointers[y] = (png_byte*) malloc(png_get_rowbytes(png_ptr, info_ptr));
}
png_read_image(png_ptr, row_pointers);
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
png_bytep pixel = &(row_pointers[y][x * 4]);
printf("(%d,%d): %d %d %d %d\n", x, y, pixel[0], pixel[1], pixel[2], pixel[3]);
}
}
for (int y = 0; y < height; y++) {
free(row_pointers[y]);
}
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
fclose(fp);
return 0;
}
```
3. 编译程序:
```
gcc -o read_png read_png.c -lpng
```
4. 运行程序:
```
./read_png example.png
```
注意,以上示例程序仅供参考,实际应用中需要根据具体需求进行修改。