Campaigns

Round-robin image comparison

Respondents see pairs of your images side-by-side and pick a favorite. Membrane generates every unique pair — a clean way to surface a clear winner from a small set.

Best for: choosing a winnerMin 2 images

When to use it

Round-robin is the right format when you have a small set of options and want a decisive outcome. It's especially good when every option is “pretty good” — forcing a pairwise pick surfaces preferences that a yes/no vote would miss.

Pick a winner

Ad creative, packaging design, thumbnails — give respondents a direct head-to-head.

Reveal subtle preferences

Pairwise framing surfaces differences that might not show up in a straight Yes/No vote.

Small, focused comparisons

Ideal for 3–6 images. Ranking scales quickly — see the pair math below.

The upload flow

Images go from your browser, not the AI

The AI generates a private upload link, you drop your images on the page, then come back and tell it you're done.

Step 1
AI sends you an upload link
Describe the campaign and the AI generates a private upload page for you.
Step 2
You upload your images
Open the link, drag files onto the page, and click “Done — Return to chat” when it's all up.
Step 3
You tell the AI you're done
Back in chat, say “uploaded”. The AI verifies and creates the campaign.

Prep

What you'll need

At least 2 images — PNG, JPEG, or WebP, up to 10 MB each. Most comparisons use 3–6.
A campaign title and description, plus a short tagline and category label.
The comparison questionrespondents will see above each pair (e.g., “Which feels more premium?”).
A reward amount — positive number.
A landing-page link.

How many comparisons respondents see

The pair count grows fast

With N images, respondents see N × (N − 1) ÷ 2 unique pairs. A set of 5 is still quick; a set of 10 is a longer ask.

Images	Unique pairs	Feels like
3	3 pairs	Quick — under a minute for most respondents
4	6 pairs	Comfortable — the sweet spot for most tests
5	10 pairs	Still fast — about 2 minutes
6	15 pairs	Noticeably longer; consider higher reward
8	28 pairs	Getting tiring — use only when decisive data is worth it
10	45 pairs	Long. Split into two round-robins if possible

Rule of thumb: keep it to 6 or fewer images. If you have more, split the set into two rounds or switch to a binary (Yes/No) survey.

How it works

Describe the comparison. Upload. Go live.

Example conversation

I want to run a pairwise comparison on our four new packaging designs. Call it “Spring packaging — head to head”. Question: “Which feels more premium?” Category: packaging. Reward: 75.
Got it. Here's your upload link — drop your four images there and name them if you want (e.g., Matte Black, Glossy White). Let me know once you're done.
https://mcp.nfthing.com/upload?session=…
Done — uploaded all four.
Confirmed. With 4 images, respondents will see 6 unique pairs. Creating the campaign now. Start it live, or hold for review?
Start it live.
Spring packaging — head to head is live. Ask me for a winner summary anytime.

Naming your images

Give each image a readable name on the upload page.

On the upload page, type a short name into the field next to each image (e.g., 'Matte black', 'Glossy white'). These names appear in your results report, so you can see exactly which option won.

Try these prompts

Copy, paste, and tweak

Pick a thumbnail

“Set up a round-robin comparison called 'New video thumbnail'. Question: 'Which one makes you want to click?'. Category: content. Reward: 30. Give me the upload link — I have four options to upload.”

Packaging head-to-head

“Run a round-robin on our five candidate packaging designs. Call it 'Packaging finalists'. Ask: 'Which feels more premium?'. Category: packaging. Reward: 75. After I upload, turn it on.”

Ad creative bake-off

“Compare three ad creatives for our app launch. Question: 'Which would you tap?'. Category: mobile apps. Reward: 40. Campaign name: 'App launch — creative test'. Send me the upload link.”

Get the winner

“My 'Packaging finalists' round-robin has been live for two days. Which design is winning, and what's the margin between the top two?”

Good to know

A few things worth knowing

Minimum images

10 MB

Max per image

PNG / JPEG / WebP

Accepted formats

Instant

Goes live after upload

Pair count scales quadratically

Each extra image adds several new pair comparisons. Keep sets small and tight — quality of attention drops as pairs pile up.

Live instantly after creation

No processing wait — flip the campaign live and responses start flowing immediately.

Name your images

Respondents don't see the names, but you do in your results. A file called “IMG_4823.png” is useless in a report — rename it on the upload page.

Pairs are randomized per respondent

Each respondent sees pairs in a different order to avoid position bias. You don't need to think about ordering.

If something goes wrong

Only one image uploaded — round-robin needs at least two. Upload at least one more and retry.
Upload link expired — ask the AI for a fresh link (one-hour window).
File type not supported — PNG, JPEG, or WebP only. Convert and retry.

Next: Binary (Yes / No)See other campaign types