How Diffusion Models Work: AI Image Generation Basics
Understand how AI creates images from noise. Simple explanation of diffusion models for non-technical readers.
Understand how AI creates images from noise. Simple explanation of diffusion models for non-technical readers.
Ever wondered how typing a few words can produce stunning images? Behind tools like CubistAI, DALL-E, and Midjourney lies a fascinating technology called diffusion models. This guide explains how they work in plain language, no PhD required.
When you type "a cat wearing a space suit on Mars" and receive a detailed image seconds later, you're witnessing diffusion models in action. But what's actually happening?
Imagine you have a clear photograph. Now imagine slowly adding static noise—like TV snow—until the image becomes pure random dots. Diffusion models learn to do this process in reverse: starting from pure noise and gradually removing it to reveal a coherent image.
The "diffusion" name comes from physics, where it describes how particles spread out over time. In AI, we're doing the opposite—starting with spread-out randomness and organizing it into meaning.
During training, the AI learns what happens when you destroy images with noise:
This is like teaching someone to clean by showing them exactly how messes are made, step by step.
When you generate an image, the AI runs backwards:
Each removal step is tiny—typically 20-50 steps total—with the image becoming clearer at each stage.
Here's where prompts come in:

Imagine generating this alien landscape. Here's what happens:
Step 0 (Pure Noise): Random colored dots with no pattern
Step 10: Vague shapes emerge—dark areas, light areas
Step 25: Rough forms visible—horizon line, spherical shapes
Step 40: Details forming—texture on spheres, sky gradients
Step 50 (Final): Complete detailed image with all elements
Each step builds on the previous, like a photograph developing in slow motion.
Instead of working with full images (slow and expensive), diffusion models work in "latent space"—a compressed mathematical representation.
Think of it like:
Working with summaries is faster while preserving the essential information.
The core of most diffusion models is a special neural network called U-Net:
The actual process of removing noise is called "denoising":
This happens dozens of times per generation.
Before Diffusion (GANs):
Diffusion Models:
Unlike previous AI that generated images in one shot, diffusion models refine progressively:
This iterative approach produces more coherent, detailed results.
Stable Diffusion XL (SDXL) is the specific diffusion model powering CubistAI. It improves on earlier versions:
Larger Model:
Dual Text Encoders:
Refinement Stage:
For faster generation, SDXL-Lightning uses "distillation":
This is why CubistAI can generate images in seconds rather than minutes.
Let's trace what happens when you submit a prompt to CubistAI:
1. Text Processing:
Your prompt: "cyberpunk city at night, neon lights, rain"
↓
Tokenized: [cyberpunk] [city] [at] [night] [,] [neon] [lights] [,] [rain]
↓
Embedded: Numbers representing meaning in 768 dimensions
2. Initial Setup:
Random noise generated: Pure static image
Text embeddings attached: Guidance vectors
Parameters set: Resolution, steps, etc.
3. Iterative Denoising:
Step 1: Major shapes influenced by "city" concept
Step 5: Night-time lighting develops
Step 15: Neon colors emerge
Step 25: Rain effects appear
Step 40: Fine details sharpen
Step 50: Final image complete
4. Output:
Latent space decoded back to pixels
Final image displayed to you
More steps generally mean better quality but slower generation:
| Steps | Speed | Quality | Best For |
|---|---|---|---|
| 4-8 | Very Fast | Good | Quick previews (Lightning) |
| 20-30 | Moderate | Very Good | Standard use |
| 50+ | Slow | Excellent | Maximum quality |
"Classifier-Free Guidance" controls how strictly the AI follows your prompt:
Different mathematical approaches to the denoising:
Diffusion models like SDXL trained on:
Reality: Diffusion models don't store or retrieve images. They learn patterns and concepts, generating entirely new combinations.
Analogy: A chef who has tasted thousands of dishes doesn't copy recipes—they understand flavor principles and create new dishes.
Reality: Returns diminish after certain points. 30 steps often looks nearly identical to 100 steps.
Reality: These models learn statistical patterns, not meaning. They don't "understand" that a cat is an animal—they know what pixel patterns associate with the word "cat."
Reality: You're not searching a database. Each image is generated new, mathematically derived from noise guided by your text.
The core equation diffusion models solve:
p(x_{t-1}|x_t) = N(x_{t-1}; μ_θ(x_t, t), σ_t²)
In plain terms: "What's the probability distribution of a slightly-less-noisy image, given this noisy image?"
The model learns μ_θ (the mean) through training, predicting where the signal is likely hiding in the noise.
How quickly noise is added/removed follows a "schedule":
Different schedules affect generation quality and speed.
How text guides image generation:
Understanding diffusion models helps you:
Experience diffusion models in action with CubistAI:
Diffusion models represent a fundamental breakthrough in AI image generation:
From random static to stunning artwork, diffusion models transform text into visual reality through elegant mathematics and massive training.
Ready to see diffusion in action? Visit CubistAI and watch your prompts transform into images through the power of diffusion models!
Learn to harness this technology better with our prompt engineering masterclass or explore SDXL-Lightning technology for the fastest generation experience.

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