254 lines
7.5 KiB
Markdown
254 lines
7.5 KiB
Markdown
# Image Generation Models - Prompting Guide
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This guide covers all available image generation models, helping you choose the right model and write optimal prompts.
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## Model Selection Quick Reference
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| Need | Recommended Model | Tool Name |
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|------|-------------------|-----------|
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| General text-to-image / image editing | Gemini (default) | `nano_banana_image_generation` |
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| Batch image generation | Gemini Batch | `nano_banana_batch_image_generation_v2` |
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| Text embedded in images | Qwen Wanxiang | `qwen_image_generation` |
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| Style transfer / editing | FLUX Kontext | `kontext_image_generation` |
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| Face / character reference | Kling | `kling_image_generation` |
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| Creative illustration / Logo / transparent background | OpenAI GPT-Image | `openai_image_generation` |
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| Artistic quality | Midjourney | `midjourney_image_generation` |
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| Many reference images (up to 14) | Seedream | `seedream_image_generation` |
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---
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## Gemini (nano_banana)
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**Default image model** with the strongest overall capabilities.
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### Model Variants
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| Variant | Model ID | Features |
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|---------|----------|----------|
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| nano_banana | gemini-2.5-flash-image | Fast, good for iteration |
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| nano_banana_2 | gemini-3-pro-image-preview | High quality |
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| nano_banana_2_flash | gemini-3.1-flash-image-preview | Default, balances speed and quality |
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### Prompt Style
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Natural language descriptions, like talking to an artist:
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```
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A serene Japanese garden in autumn, with a wooden bridge over a koi pond.
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Red and golden maple leaves float on the water surface. Soft morning mist
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rises from the pond. Shot in the style of a landscape photograph, natural
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lighting, shallow depth of field focusing on the bridge.
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```
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### Image Editing
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Provide reference images via `image_paths`, then describe the desired changes in the prompt:
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```
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image_paths: [original.jpg]
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prompt: "Change the background to a sunset beach scene, keep the person and their pose exactly the same"
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```
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### Resolution
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Supports 1K / 2K / 4K, default 2K. 2K is sufficient for video first frames.
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---
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## Qwen Wanxiang (qwen)
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**Best choice for embedding text in images**. Only supports image editing (reference image required).
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### Use Cases
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- Adding text titles to images
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- Modifying existing text in images
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- Poster / cover creation
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### Prompt
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```
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image_paths: [background.jpg]
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prompt: "Add the text 'Brightest Star in the Night Sky' in elegant calligraphy style at the center of the image, white text with subtle glow effect"
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```
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---
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## FLUX Kontext (kontext)
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**Best choice for style transfer and image editing**.
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### Strengths
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- Converting photos to specific art styles
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- Changing art style while maintaining composition
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- Multi-image reference fusion
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### Prompt
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```
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image_paths: [photo.jpg]
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prompt: "Transform this photo into Studio Ghibli anime style, maintain the same composition and character pose, soft watercolor textures, warm pastel colors"
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```
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### Aspect Ratios
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Supports a rich set of aspect ratios: 1:1, 16:9, 9:16, 3:2, 2:3, 4:3, 3:4, 4:5, 5:4, 21:9, 7:4, 4:7
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---
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## Kling (kling)
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**Best choice for face and character reference generation**.
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### Reference Modes
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| Mode | Use Case |
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|------|----------|
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| `subject` | Preserves overall appearance (clothing, pose, style) |
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| `face` | Preserves facial features only (can change outfit, scene) |
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### Prompt
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```
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# Face mode: Keep face, change scene
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image_path: face_reference.jpg
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reference_type: face
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prompt: "A woman in a traditional red qipao standing in a lantern-lit ancient Chinese street at night, full body shot, elegant pose, cinematic lighting"
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# Subject mode: Preserve overall appearance
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image_path: character_reference.jpg
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reference_type: subject
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prompt: "The same person standing on a rooftop at sunset, wind blowing through their hair, dramatic sky background, cinematic wide shot"
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```
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### Batch Generation
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`kling_batch_image_generation` supports independent prompt, reference image, reference mode, and aspect ratio for each image.
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---
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## OpenAI GPT-Image (openai)
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**Best choice for creative illustrations, logos, and transparent backgrounds**.
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### Special Capabilities
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- Transparent background images (ideal for logos, stickers, UI elements)
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- Creative concept visualization
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- Abstract art
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### Prompt
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```
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prompt: "A minimalist logo of a phoenix rising from flames, clean vector style, bold lines, gradient from deep red to bright gold"
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size: "1024x1024"
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quality: "high"
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```
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### Image Editing
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```
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image_paths: [original.jpg]
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prompt: "Remove the background and make it transparent, keep only the main subject"
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```
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---
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## Midjourney (midjourney)
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**Best choice for artistic quality and stylization**.
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### Version Selection
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Append version flag at the end of the prompt:
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- `--v 7`: V7 (default), realistic and general purpose
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- `--niji 7`: Niji7, anime/manga style
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### Core Parameters
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| Parameter | Function | Example |
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|-----------|----------|---------|
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| `--ar` | Aspect ratio | `--ar 16:9` |
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| `--sref` | Style reference URL | `--sref https://example.com/style.jpg` |
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| `--cref` | Character reference URL | `--cref https://example.com/char.jpg` |
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| `--cw` | Character reference weight (0-100) | `--cw 50` |
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### Prompt Style
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Midjourney favors **concise, evocative descriptions** — no need to be overly verbose:
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```
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prompt: "ancient samurai meditating under cherry blossoms, moonlit courtyard, atmospheric fog, cinematic lighting, dramatic shadows --ar 16:9 --v 7"
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```
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### Reference Images
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Provide local reference images via `image_paths`:
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```
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image_paths: [reference.jpg]
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prompt: "a warrior in similar armor style standing on a cliff overlooking a vast ocean, epic scale, golden hour --ar 16:9 --v 7"
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```
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---
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## Seedream (seedream)
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**Supports the most reference images** — version 4.5 supports up to 14 reference images.
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### Model Selection
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| Model | Features |
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|-------|----------|
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| doubao-seedream-4-0-250828 | Standard version |
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| doubao-seedream-4-5-251128 | New version, supports up to 14 reference images |
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### Ideal Use Cases
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- Scenarios requiring many reference images to constrain style
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- Multi-character consistency (provide multiple character reference images)
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- Complex scene reconstruction
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### Prompt
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```
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image_paths: [ref1.jpg, ref2.jpg, ref3.jpg, ...]
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prompt: "A group photo of these characters together in a modern office setting, natural lighting, professional photography style, everyone is smiling and looking at the camera"
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```
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---
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## General Prompting Tips
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### 1. Optimizing for Video First Frames
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When generating images intended as video first frames:
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```
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✓ Character's mouth slightly open (helps with lip sync)
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✓ Pose suggests motion (e.g., mid-step, mid-turn)
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✓ Leave room for motion in the frame (don't push subject to edges)
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✓ Avoid extreme perspective (video models struggle to maintain it)
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✗ Don't generate overly static "passport photo" compositions
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```
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### 2. MV First Frame Batch Generation Strategy
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```
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1. Determine art style → select primary image generation model
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2. Use Kling face mode to lock character facial consistency
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3. Batch generate first frames for each scene with the selected model
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4. Use Kontext to unify style (if inconsistencies exist)
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5. After confirmation, send to video model for generation
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```
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### 3. Style Consistency
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Tips for maintaining unified style across a set of images:
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- Use the same style keyword suffix
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- Use Midjourney `--sref` to lock style
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- Use Kling `face` mode to lock character appearance
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- Use Kontext with the same style reference image for all images
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- In batch generation tools (Gemini batch / Kling batch), use the same style description suffix for each image
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