gistfile1.m

    uint16_t pix;
    uint16_t min = 34464;
    uint16_t max = 0;
    uint16_t *d = (uint16_t*) imgData;
    for (int i = 0; i < 512 * 512; i++) {
        pix = d[i];
        if (pix > max)
            max = pix;
        else if (pix < min)
            min = pix;
    }
    NSLog(@"MIN PIX VAL: %d -- MAX PIX VAL: %d", min, max);
    
    void *compressed = malloc(512 * 512);
    uint8_t *cd = (uint8_t*) compressed;
    for (int i = 0; i < 512 * 512; i++) {
        pix = d[i];
        cd[i] = pix >> 8;
    }
    
    NSData *data = [NSData dataWithBytes:cd length:512*512];