OCR/ImageTreatment/Filter/cleanerimage.c

#include "cleanerimage.h"

#include "../display.h"

void grayscale(SDL_Surface *img)
{
    Uint32 pixel;
    Uint8 r, g, b;
    int w = img->w;
    int h = img->h;

    for (int i = 0; i < w; i++)
    {
        for (int j = 0; j < h; j++)
        {
            pixel = getpixel(img, i, j);
            SDL_GetRGB(pixel, img->format, &r, &g, &b);
            Uint8 results = 0.3 * r + 0.59 * g + 0.11 * b;
            pixel = SDL_MapRGB(img->format, results, results, results);
            putpixel(img, i, j, pixel);
        }
    }
}

void binerize(SDL_Surface *img)
{
    Uint32 pixel;
    Uint8 r, g, b;
    int w = img->w;
    int h = img->h;

    for (int i = 0; i < w; i++)
    {
        for (int j = 0; j < h; j++)
        {
            pixel = getpixel(img, i, j);
            SDL_GetRGB(pixel, img->format, &r, &g, &b);
            Uint32 average = (r + b + g) / 3;

            if (average > 150) /*we can make an average here*/
            {
                r = 255;
                g = 255;
                b = 255;
            }
            else
            {
                r = 0;
                g = 0;
                b = 0;
            }

            pixel = SDL_MapRGB(img->format, r, g, b);
            putpixel(img, i, j, pixel);
        }
    }
}
int IsValid(int x, int y, int w, int h)
{
    return x >= 0 && x < w && y >= 0 && y < h;
}

SDL_Surface *Convolute(SDL_Surface *img, float mask[3][3])
{
    int offset = 3 / 2;
    Uint8 r, g, b;
    Uint32 pixel = 0;

    SDL_Surface *copy = CreateWhiteSurface(img->w, img->h, img);
    for (int y = 0; y < img->h; ++y)
    {
        for (int x = 0; x < img->w; ++x)
        {
            float red = 0;
            float green = 0;
            float blue = 0;

            for (int dy = -offset; dy <= offset; ++dy)
            {
                for (int dx = -offset; dx <= offset; ++dx)
                {
                    if (IsValid(x + dx, y + dy, img->w, img->h))
                    {
                        pixel = getpixel(img, x + dx, y + dy);
                        float coefficient = mask[dy + offset][dx + offset];
                        SDL_GetRGB(pixel, img->format, &r, &g, &b);
                        red += r * coefficient;
                        green += g * coefficient;
                        blue += b * coefficient;
                    }
                }
            }

            pixel = SDL_MapRGB(img->format, Restrict256(red),
                               Restrict256(green), Restrict256(blue));
            putpixel(copy, x, y, pixel);
        }
    }

    return copy;
}

int Restrict256(int n)
{
    if (n < 0)
        return 0;
    if (n > 255)
        return 255;
    return n;
}

void ConstrastRenforcement(SDL_Surface *img, int delta)
{
    double factor = (259 * (delta + 255)) / (255.0 * (259.0 - delta));
    Uint32 pixel;
    Uint8 r;
    Uint8 g;
    Uint8 b;
    int w = img->w;
    int h = img->h;

    if (delta == 259)
    {
        delta = 258;
    }

    for (int i = 0; i < w; i++)
    {
        for (int j = 0; j < h; j++)
        {
            pixel = getpixel(img, i, j);
            SDL_GetRGB(pixel, img->format, &r, &g, &b);
            r = Restrict256(factor * (r - 128) + 128);
            g = Restrict256(factor * (g - 128) + 128);
            b = Restrict256(factor * (b - 128) + 128);
            pixel = SDL_MapRGB(img->format, r, g, b);
            putpixel(img, i, j, pixel);
        }
    }
}

void noiseReduction(SDL_Surface *img)
{
    int w = img->w;
    int h = img->h;
    int pixelmap[9];

    for (int i = 1; i < h - 1; i++)
    {
        for (int j = 1; j < w - 1; j++)
        {
            pixelmap[0] = getpixel(img, j - 1, i - 1);
            pixelmap[1] = getpixel(img, j, i - 1);
            pixelmap[2] = getpixel(img, j + 1, i - 1);
            pixelmap[3] = getpixel(img, j - 1, i);
            pixelmap[4] = getpixel(img, j, i);
            pixelmap[5] = getpixel(img, j + 1, i);
            pixelmap[6] = getpixel(img, j - 1, i + 1);
            pixelmap[7] = getpixel(img, j, i + 1);
            pixelmap[8] = getpixel(img, j + 1, i + 1);
            array_select_sort(pixelmap, 9);
            int med = pixelmap[4];
            putpixel(img, j, i, med);
        }
    }
}