Image Reveal w/Quiz

It really depends on the type of questions you're using and what you mean by ‘generate image.’ One approach is to simulate this using a Pick One Freeform question. Each response can trigger a state change on an image, allowing you to animate it in a way that mimics an image being generated or loaded.

You could also enhance this effect by using JavaScript in the background to create a more realistic ‘loading’ animation, instead of relying on the default top-to-bottom wipe animation in Storyline.

If you're just starting out, I’d recommend experimenting with different question types and seeing which one best fits the interaction you're trying to achieve.

I don’t have a ready-made template or interaction for this, but the idea below is just a starting point. I’d suggest first defining your concept, maybe sketching a simple layout or mockup of how you want it to look. Having a clear idea in place will make it much easier before moving on to the more technical work in Storyline.

As a corollary to Nedim's solid answer, I've found a simple method for reveal to be removing squares that cover an image.

The solution commonly offered is to take the large image you want to reveal, segment it out into many pieces, arrange them on a slide to reform the image, and then set their default state to Hidden or something similar, revealing them according to certain triggers. This is fine but people tend to see the amount of work involved in segmenting one picture into many small pieces. What if you want to change the picture? What if you want a different number of pieces?

If you instead cover up the large image with some simple squares, those can be hidden or animated away to slowly reveal the whole image underneath, and requires less work.

Bonus points if instead of simple squares, you cover the large image with buttons, and the learner uses those buttons to attempt certain questions. This allows for learners who answer incorrectly to attempt a different question or reattempt the same, and even allows for certain questions to correspond to certain parts of the underlying image.