Libraries - Estia-1a/projetGenieInfo_public GitHub Wiki

estia-image library

In order for you to focus mainly on image manipulation, we created a library to handle the manipulation of image files. The library proposes 3 functions to read an image file, to write an image file, and to free memory.

Read an image file

/**
 * Return some data about an image file
 * @param[in] filename Name of the file to be open
 * @param[out] data Reference to the pointer that points to the pixel array
 * @param[out] width Width of the image
 * @param[out] height Height of the image
 * @param[out] channel_count Number of channels
 * @return 0 on failure and non-0 on success.
 */
int read_image_data(const char *filename, unsigned char **data, int *width, int *height, int *channel_count);

This function considers a file name (filename) and provides information of this image: the data itself, i.e. the RGB values of each pixels, but also its size (width and height) and the number of channels encoding the color (3 in our case: RGB. But it could be more if we considered the alpha transparency for instance).

To use it, simply call

read_image_data(the_file_name, &data, &w, &h, &n);

With correctly declared variables the_file_name, data, w, h, and n.

Write an image file

/**
 * Writes into a png image file
 * @param[in] filename Name of the file to be written into
 * @param[in] data Reference to the pixel array to be written
 * @param[in] width Width of the image
 * @param[in] height Height of the image
 * @return 0 on failure and non-0 on success.
 */
int write_image_data(const char *filename, unsigned char *data, int width, int height);

This function is similar to the read_image_data function. Just use the filename (e.g., "./images/output/my_new_image_name.jpg) and its pixels (data):

write_image_data(output_image_name, new_data, new_w, new_h);

With correctly declared and populated variables.

Free memory

/**
 * Frees stbi-related buffers and resources
 * @param[in] data The buffer allocated by readImageData buffer to be freed
 */
void free_image_data(unsigned char *data);