Text-to-Image vs. Image-to-Image: Understanding AI Generation Modes

AI image generation offers two fundamental modes of operation: text-to-image (txt2img) and image-to-image (img2img). Understanding the differences and strengths of each mode is essential for getting the most out of AI image generation on CrIAr.

Text-to-Image (txt2img)

Text-to-image is the most common form of AI image generation. You provide a text description, and the AI creates an image from scratch based on random noise guided by your prompt.

How It Works

1. The AI starts with random noise (like static on a TV)
2. Your text prompt is encoded into a mathematical representation
3. Step by step, the noise is refined into an image guided by your prompt
4. After all steps, the final image is decoded and displayed

Best Used For

• Creating entirely new images from your imagination
• Exploring ideas and concepts quickly
• When you have no reference image to start from
• Maximum creative freedom

Image-to-Image (img2img)

Image-to-image takes an existing image as a starting point and modifies it based on your prompt. Instead of starting from random noise, the AI starts from a noised version of your input image.

How It Works

1. Your input image is encoded and noise is added to it
2. A "denoising strength" parameter controls how much noise is added (and thus how different the output will be from the input)
3. The AI then denoises the image, guided by your prompt
4. The result blends elements of the original image with new AI-generated content

The Denoising Strength

This is the key parameter in img2img:

• Low (0.1-0.3): Subtle changes — the output looks very similar to the input with minor modifications
• Medium (0.4-0.6): Noticeable changes while keeping the overall structure and composition
• High (0.7-0.9): Major changes — the composition may be preserved but content is significantly altered
• 1.0: Essentially the same as txt2img — starting from scratch

Best Used For

• Refining and improving existing images
• Changing the style of a photo or artwork
• Using sketches as a composition guide
• Enhancing low-resolution images
• Iterative creative refinement

Combining Both Modes

Professional AI artists often combine both modes in a workflow:

1. Generate with txt2img: Create initial concepts and compositions
2. Select the best: Choose the most promising generation
3. Refine with img2img: Use the selected image as input for img2img with a low-medium denoising strength to refine details
4. Final polish: Use AI editing tools like Flux Kontext or Qwen Edit for targeted modifications

CrIAr supports this entire workflow within a single platform, making it easy to move between generation modes and editing tools.

Tips for Each Mode

txt2img Tips

• Use detailed prompts with composition guidance
• Generate multiple images and select the best one
• Experiment with different seeds for variety

img2img Tips

• Start with a clean, well-composed source image
• Adjust denoising strength based on how much change you want
• Use the same prompt style as the source image's model for consistency