a.c

//to compile with mingw: gcc a.c -mconsole -mwindows
#include <stdio.h>
#include <windows.h>

int main(void)
{
    WORD vals[3][256];

    int i, j;
    for (i = 0; i < 3; i++) for (j = 0; j < 256; j++) vals[i][j] = 0;

    HDC hdc = GetDC(NULL);

    if (GetDeviceGammaRamp(hdc, &vals) == 0) {
        printf("fail!\n");
        return 1;
    }

    for (i = 0; i < 256; i++)
        printf("%u\t%u\t%u\n", vals[0][i],vals[1][i],vals[2][i]);

    return 0;
}