I use this code:
sf :: Image image;
image.create(1024, 768, sf :: Color());
sf :: Texture texture;
texture.loadFromImage(image);
sf :: Sprite sprite(texture);
// some code here
for ( int i = 0; i < WIDTH; ++i )
for ( int j = 0; j < HEIGHT; ++j )
image.setPixel(i, j, f(t, i, j, image.getPixel(i, j)));
texture.loadFromImage(image);
But I think this isn't quick solution. Can You help?