Runway Gen-4.5: Animate One Part of an Image (2026)
🚀 Quick start
- Upload a clean static photo or AI image into Runway Gen-4.5 Image-to-Video.
- Describe motion exclusively for the moving element (e.g., 'only the river flows, water ripples rapidly').
- Add negative constraints in your prompt: 'camera locked, static background, no trees moving' to isolate movement.
- Budget credits: Gen-4.5 burns 12 credits/second (60 credits for 5s, 120 credits for 10s). Standard ($15/mo) gives 625 credits/mo.
💡 Why use Runway for this
Animating still photographs or product renders normally requires complex After Effects masking, particle plugins, or 3D camera projection. Runway Gen-4.5 interprets image physics and depth directly from your input frame, allowing you to generate subtle, realistic motion (like flowing water, steam rising, or blinking eyes) in under 60 seconds with simple text instructions.
📋 What you need
A Runway account (Free tier gives 125 one-time credits; Standard $15/mo unlocks Gen-4.5 and watermark-free exports), a high-resolution static PNG or JPEG image, and clear prompt instructions.
🛠️ How to Animate One Part of an Image (5 steps)
Step 1
Open Gen-4.5 Image-to-Video: In your Runway dashboard, navigate to the video generation studio and select Gen-4.5. Select 'Image + Description' mode rather than pure text-to-video.
Step 2
Upload your static master frame: Drag and drop your image into the master input box. For cleanest motion isolation, pick an image where the subject you want to animate has clear visual boundaries from the background (e.g. a river between stone banks, or steam above a coffee cup).
Step 3
Write an isolated motion prompt: In the prompt field, describe ONLY the motion of the moving element, followed by explicit lock statements for the rest of the frame. For example: 'Only the river flows swiftly to the right. Static camera, no camera pan, background trees and rocks remain completely frozen and still.' Do not look for the retired Gen-2 Motion Brush tool.
Step 4
Set duration and aspect ratio: Choose a 5-second duration for your initial test (burning 60 credits at 12 credits/sec) rather than committing 120 credits to a 10-second render. Keep Camera Motion set to fixed (Static).
Step 5
Generate and review: Click 'Generate'. Review the 720p output. If background elements warp, increase the weight of your negative prompt: 'completely motionless background, locked tripod shot'. Download the MP4 when satisfied.
📦 What you'll get
A 5-second 720p MP4 clip where the selected element (e.g. water or smoke) animates smoothly with natural physics while the rest of the photo stays entirely still as a locked tripod shot.
💰 Pricing (checked 2026-10-15)
| Plan | Price | What you get for this workflow | Official link |
|---|---|---|---|
| Runway Free | $0 |
125 one-time credits (approx. two 5s clips), watermarked exports, 5GB storage | pricing ↗ |
| Runway Standard | $15/mo monthly, $12/mo yearly ($144/yr) |
625 credits/mo (~10 five-sec Gen-4.5 clips), watermark-free, 100GB storage, all models unlocked | pricing ↗ |
| Runway Pro | $35/mo monthly, $28/mo yearly ($336/yr) |
2,250 credits/mo (~37 five-sec Gen-4.5 clips), 500GB storage, faster priority generation queue | pricing ↗ |
| Runway Max | $95/mo monthly, $76/mo yearly ($912/yr) |
9,500 credits/mo (~158 five-sec clips), ProRes export options, 1-month credit rollover | pricing ↗ |
| Kling AI Standard | $10/mo |
660 credits/mo, includes manual Motion Brush tool for selective masking | pricing ↗ |
📋 Copy-paste prompts
"Only the water in the river flows rapidly downstream towards the right side of the frame. Subtle foam ripples on surface. Completely static camera, locked tripod shot, all surrounding mountains, trees, and stones remain perfectly motionless.""Only the steam rises gently from the coffee mug in soft wisps upward. Static camera, warm ambient lighting. Coffee mug, table, and background remain completely frozen and still, no camera drift.""Only the flame of the candle flickers gently with subtle wind agitation. Soft cast shadows oscillate. The candle wax, candle holder, and surrounding wooden table remain completely static. Locked camera."⚠️ Common mistakes
⚖️ Runway vs Alternatives
Kling AI (Standard $10/mo) and Luma Dream Machine ($29.99/mo) are the main alternatives. Kling AI still features a dedicated Motion Brush mask tool if you need to manually paint pixels on screen. However, Runway Gen-4.5 delivers superior natural fluid dynamics, lighting consistency, and prompt fidelity when directed with prompt-isolated motion. Pika 2.1 ($10/mo) is another option, though geared more towards playful visual effects than cinematic realism.
💡 Pro tips & power tricks
- Always specify 'camera locked, static tripod shot' when animating a single element so the camera doesn't drift.
- Start with 5-second generations (60 credits) instead of 10-second renders (120 credits) while testing prompts.
- Pick source images with strong contrast between the moving subject and the surrounding static scene.
❓ Frequently Asked Questions
Q: Does Runway still have Motion Brush?
No. Motion Brush was exclusive to Gen-2, which Runway retired and shut down in May 2025. In Gen-4.5, motion is controlled through prompt isolation.
Q: How many credits does Gen-4.5 use per second?
Gen-4.5 uses 12 credits per second of video. A standard 5-second clip costs 60 credits, and a 10-second clip costs 120 credits.
Q: What video resolution does Gen-4.5 export?
Gen-4.5 exports at 720p HD resolution as standard MP4 files. Pro and Max plans offer higher priority generation and ProRes exports on select workflows.
Q: Can I animate an image for free on Runway?
Yes, using Runway's 125 one-time free credits, which gives you enough credits to generate two 5-second clips. Free exports carry a watermark.
Q: Do Runway credits roll over every month?
Monthly credits on Standard and Pro plans do not roll over; they reset each billing period. The Max plan ($95/mo) allows 1 month of unused credit rollover.
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