https://github.com/blhmr/ppm6
Last synced: 4 months ago
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- Host: GitHub
- URL: https://github.com/blhmr/ppm6
- Owner: blhmr
- License: mit
- Created: 2024-08-21T22:39:09.000Z (10 months ago)
- Default Branch: main
- Last Pushed: 2024-08-22T10:12:13.000Z (10 months ago)
- Last Synced: 2025-01-06T13:49:22.898Z (6 months ago)
- Language: C
- Size: 32.2 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# PPM6: Portable Pixmap Format Library (P6)
This single header library manages PPM files using C code, aswell as to hide text inside of images
## How does it work?
Every `.ppm` image consists of many pixels, let's take for example this image:
(Converted to png since Github does not display ppm files by default)
This is a 64x64 ppm image generated by code by randomizing each property of a pixel (Since a pixel is in RGB format)
Code:
```c
#include "ppm6.h"
#include // For seed, rand_r...
// Width and height of our image
#define WIDTH 64
#define HEIGHT 64
// Function-like macro to get random integer between a range
#define GET_RAND_INT(MIN, MAX, SEED) (unsigned char) rand_r(SEED) % (MAX - MIN + 1) + MIN
int main(void) {
// Used for randomisation
int seed = time(0);
// Initializing an image struct
struct PPM6_Image img = {0};
// Some error handling
if (PPM6_init_image(&img, WIDTH, HEIGHT) != 0) {
fprintf(stderr, "Error initializing PPM6 image\n");
// Return failure
return -1;
}
// Iterating over the image
for (size_t x = 0; x < img.width; x++) {
for (size_t y = 0; y < img.height; y++) {
// Getting random int from 0 to 255 for pixels
unsigned char random_r = GET_RAND_INT(0, 255, &seed);
unsigned char random_g = GET_RAND_INT(0, 255, &seed);
unsigned char random_b = GET_RAND_INT(0, 255, &seed);
// Initializing the random pixel
struct PPM6_Pixel pixel = SET_PIXEL(
random_r, random_g, random_b
);
// Setting the pixel into the image struct (x and y are coordinates of where the pixel is placed)
PPM6_set_pixel(&img, &pixel, x, y);
}
}
// Saving the image into a file
if (PPM6_save_image("images/output.ppm", &img) != 0) {
fprintf(stderr, "Could not save to file\n");
}
// Deallocating the image
PPM6_free_image(&img);
// Return success
return 0;
}
```
## How can I store strings?
One way is to take the string, devide it into triplets then make them pixels, for example consider this string:
"ABCDEFGHIJKFMNOP"
This string can be devided into pixels, because each character represents an integer (using [ASCII](https://fr.wikipedia.org/wiki/Fichier:ASCII-Table-wide.svg))
Pixel 1: "ABC" -> (65, 66, 67)
Pixel 2: "DEF" -> (68, 69, 70)
Pixel 3: "GHI" -> (71, 72, 73)
...
But there is a function that does the job:
```c
#include "ppm6.h"
int main(void) {
const char *str = "Hello this is a bit of a long string in C that is used to store it into a ppm file, have a great day";
// Variable that stores the number of pixels needed
size_t number_of_pixels = 0;
// Initializing our image struct
struct PPM6_Image img = {
.height = 1, // The height is initialized to 1 so the image can be a horizontal chain of pixels
// You can choose another way to do it
.data = PPM6_str_to_pixels(str, &number_of_pixels), // This function takes a string (and a memory adress of a size_t variable) so it returns the array of pixels
};
img.width = number_of_pixels; // Now you set the width of the picture to be the number of pixels needed
PPM6_save_image("output-2.ppm", &img);
PPM6_free_image(&img);
return 0;
}
```
Output:
## How can I get the strings?
```c
#include "ppm6.h"
int main(void) {
struct PPM6_Image img = {0};
PPM6_load_image("images/output-2.ppm", &img);
char *hidden_message = PPM6_image_to_str(&img); // Turns image into a string
printf("%s\n", hidden_message);
free((void*)hidden_message);
PPM6_free_image(&img);
return 0;
}
```
Output:
```
Hello this is a bit of a long string in C that is used to store it into a ppm file, have a great day
```
# License
Mit license