The Colab notebooks actually have a "target image" parameter. I haven't added it to NightCafe Creator yet, and haven't even experimented much with it on Colab, but it's definitely on my to-do list.

However, adding keywords like "watercolour painting", "van gogh painting" etc goes a long way to getting more precise results.

One big difference between style transfer and GAN art is that style transfer never changes the shape of things. E.g. you can't put in a woman's face and a cubist painting and get out a rearranged version of the face (as cubists do). It will have all the hallmarks of cubism, but it's still recognisable as the original photo.

With GAN art though, you can put that photo in as a start image, say "Cubist painting of a woman's face", and the GAN will actually rearrange the face like a cubist would.