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Pixels

You will solve this exercise starting from the pixels.c file located in the drills/tasks/pixels/support directory.

Consider the structure of a pixel and an image described in the pixel.h file:

typedef struct Pixel {
    unsigned char R;
    unsigned char G;
    unsigned char B;
} Pixel;

typedef struct Picture {
    int height;
    int width;
    Pixel **pix_array;
} Picture;

Implement the following:

  • The reverse_pic(struct picture *pic) function, which takes a Picture as a parameter and returns the reversed image. By a reversed image, we mean the inversion of the rows of the pix_array matrix in the Picture structure.
  • The color_to_gray(struct picture *pic) function, which takes a Picture as a parameter and returns the new image by converting each pixel to its grayscale value. The grayscale value of a pixel is calculated using the following formula:
p.r = 0.3 * p.r;
p.g = 0.59 * p.g;
p.b = 0.11 * p.b;

IMPORTANT: Accessing the elements of the pixel matrix will be done using pointer operations. Hint: For simplicity, you can use the following macro:

#define GET_PIXEL(a, i ,j) (*(*((a) + (i)) + (j)))

If you're having difficulties solving this exercise, go through this reading material.