Best photo for image to video: check yours before you spend credits

Most "best photo" pages say "use a high-resolution image" and stop. This page gives you a checker to run on your own photo, with every hard limit taken from vendor docs.

Check your photo for image to video

The checker below tests one photo against the published input limits plus a sharpness score and a face-size score. It runs in your browser and never uploads the file.

Green lines pass. Yellow lines are worth fixing. Red lines break a published limit or flag a blurry photo.

What are the image to video photo requirements?

The hard image to video photo requirements are a supported format, a file under the size limit, a minimum side length on some models and an aspect ratio inside the model's range.

These numbers come from Runway's API input page, which covers Runway's own models and the third-party models it hosts. Apps that call a vendor directly can use different limits.

Other models on that page state no minimum, but Runway advises against reference images under 640 x 640 px or above 4K. Treat 640 px as your working floor.

What is the best aspect ratio for an image to video photo?

The best aspect ratio is the one you plan to publish in, because a photo with a different ratio is cropped from the center.

Runway's docs say that if the input is not exactly the requested ratio, the model auto-crops it from the center. Third-party models on the same page, including Veo 3.1, Kling 4.0 and MiniMax H3 Max, may crop or resize in other ways. Seedance models do not reject images outside 0.4 to 2.5. They pad them with black bars, top and bottom for wide images and left and right for narrow ones.

Worked example: a phone portrait made into 16:9

This is the math for a center crop, the default on Runway's API. A 3000 x 4000 portrait has a ratio of 0.75. A 16:9 video has a ratio of 1.778.

1. Width stays at 3000 px.
2. The 16:9 frame needs a height of 3000 / 1.778 = 1,687.5 px.
3. The model keeps 1,687.5 of 4,000 rows, which is 42%.
4. The top 1,156 rows and the bottom 1,156 rows are cut away.

If the face sits in the top third of that portrait, a center crop can cut it off. Request 9:16 instead (0.5625) and the photo is cropped on the sides: 4,000 x 0.5625 = 2,250 px of the 3,000 px width stay, which is 75%. The checker shows these percentages for 16:9, 9:16 and 1:1.

Does blur or face size matter for character image to video?

For character image to video, a blurry photo or a very small face gives the model little detail to hold, so the face is more likely to change during the clip.

Runway's input page gives no blur score or face-size threshold, so the checker scores both itself. The sharpness score is the variance of a Laplacian filter on a 512 px grayscale copy of your photo, where lower means softer. The cut-offs of 20 and 60 are starting points for comparing photos. Score two photos of the same subject and pick the higher one.

Face size works the same way. The checker uses your browser's face detector when it has one and measures the face box as a share of the photo. Under 1% it warns you. A tighter crop with the face and shoulders in frame gives the model more pixels of the face.

Which photos are best for AI video?

The best photos for AI video show one clear subject, even light, a plain or simple background and room around the subject for movement.

Use this checklist before you generate:

• The file is JPEG, PNG or WebP and under the size limit for how you upload it.
• The shorter side is at least 640 px, and never under 300 px (256 px for MiniMax H3 Max keyframes).
• The ratio is inside the model's range and close to the ratio you will publish.
• The face, hands or product you want to animate are inside the center crop.
• The subject is sharp. Motion blur and heavy beauty filters give the model little to work with.
• There is one main person. Group photos let the model pick who moves.
• You have the right to use the face and any characters in the picture.

Can I use a photo of a real person or a cartoon character?

Use your own photos, people who agreed, and characters you created. Each platform sets its own limits on likeness and copyrighted characters.

Runway's API moderates requests with recognizable public figures by default, and a moderated generation costs the same credits as a successful one. A rejected celebrity photo is a paid mistake. A dance or movie-scene trend that uses someone's face or a copyrighted character runs on that person's consent or the rights holder's terms, and the rules vary by country and use. The platform's policy page lists its exact categories.

How do I fix a photo that fails the check?

Fix the first red line, then run the checker again, because one fix often clears the others.

1. Wrong format: export a JPEG or PNG from your photo app.
2. Too large: resize to about 2,000 px on the long side and export at medium quality. A 3.3MB file fits as a data URI.
3. Ratio out of range: crop to the ratio you will publish, with the subject centered.
4. Too soft: use the original file, not a screenshot or a chat-app copy.
5. Face too small: crop to head and shoulders.

When the photo passes, pick a model and write the motion prompt. The image-to-video guide for Kling covers one model in detail, the prompt generator helps with the motion text, and the model finder narrows the choice. To budget retries, use the cost calculator. All guides are listed on the Learn hub.

What the checker covers

The checker validates the limits Runway published as of 2026-10-27: format, file size, minimum side and aspect range per model. It adds a sharpness and face-size score so you can pick the better of two photos. Moderation decisions happen at generation time, so check the moderation page for what Runway blocks.