Alt Texts from the Picture
An alt text is the sentence a screen reader reads out, an image search indexes and a browser shows when the picture does not load. The SEO Engine writes it from the picture itself: a vision model looks at every gallery picture, and a sentence is written only for pictures that demonstrably show their item.
Two sentences describe the procedure:
No alt text for a picture that does not fit. If a picture shows something other than the item — a headset on a charging cradle, a label roll with another part number — it is held back, and no sentence is written for it at all.
No sentence reaches a picture without a human. Every proposal waits in the Alt Text Review until somebody accepts it.
Preview
The feature is registered as Preview. It is fully usable; the label says it may still change after the first catalogue runs.
Prerequisites
- A vision model as a deployment of its own in the merchantCENTRAL AI Setup, for example
gpt-6-sol, with Accepts Images and — for reasoning models — Reasoning Model. Check it with Test Connection. - Under Model per Feature, assign the feature Image Alt Texts to that deployment. The listing drafts keep their model.
- The feature Image Alt Texts is active under Copilot & AI Capabilities (it is after installation).
Without the assignment the feature does not fall back to the standard model; it says what is missing.
The procedure
For every item, in five stages:
| Stage | What happens |
|---|---|
| 1. Blind analysis | The model sees only the picture, not the item — so it cannot see what it expects. It reports the kind of picture, the view, the object, visible parts, legible text, colours and background. The picture is scaled down to at most 1024 pixels first. The analysis is stored per file; the same file on many items is paid for once. |
| 2. Fit check | A separate call compares every analysis with the item data and judges: fits, does not fit or unclear. Reasons for "does not fit": another product type, a different brand or type number, a clearly different body colour, a sample or prototype notice. Packaging, scope of delivery, drawings and logos count as fitting. |
| 3. Writing | Only pictures that fit go on. The writing call gives its own verdict first, then the sentence. If it disagrees with the fit check, the picture is held back. |
| 4. Code checks | At most 125 characters, the product name included, no plain background, no "picture of …", no conflict note in the sentence; different files get different sentences, the same file the same one. On a violation there is one repair round. |
| 5. Approval | The proposal waits in the Alt Text Review for Accept. |
A missing verdict, an unreadable answer or a picture left out of the answer counts as unclear — the picture is held back.
What the model gets
- In the analysis: the picture — nothing else.
- In the fit check and writing: brand, manufacturer, manufacturer part number, marketplace category, current title, item description, item category, item attributes and the analyses of the pictures. When writing, also the existing alt texts of the gallery as the house style, and your style instructions from the setup.
No prices, no stock, no customer or vendor data. The picture and the item data never go to the model in the same call.
Status per picture
| Status | Meaning | Alt text in the shop |
|---|---|---|
| New | Not checked yet, or the check failed (picture not reachable, the AI did not answer). The job tries up to three times. | unchanged |
| Review Image | The fit check or the writer says "does not fit" or "unclear". No sentence is written. | unchanged |
| Review Text | The sentence still breaks a rule after the repair. | unchanged |
| Proposal | Every check passed. | unchanged until accepted |
| Accepted | Approved and written to the item picture, source AI. | new text |
| Rejected | Discarded. Proposed again only when the picture file changes or somebody drafts again. | unchanged |
| Kept | The picture fits and already has an alt text, which stays. | unchanged |
The Alt Text Review
Via search: Alt Text Review. The page first shows everything waiting for a person; the views Pictures to Review and Proposals narrow it down.
| Action | Effect |
|---|---|
| Accept | Writes the proposal to every marked picture. Rows without a proposal, and pictures whose file or alt text changed since the check, are skipped. |
| Reject | Discards the marked proposals. |
| Picture Fits | For a false alarm: confirms that the picture shows the item and drafts the sentence right away. The confirmation holds for this file on this item; later checks do not ask again. |
| Draft Again | Checks all pictures of the marked items again and writes new sentences — also for pictures that already have an alt text. |
| Show Picture | Opens the picture in the browser. |
| Item | Opens the item — to remove a wrong picture, or to correct wrong item data. |
You can correct a proposal in Proposed Alt Text before accepting it; a sentence in Review Text can be fixed the same way and then accepted. The column Items Using the File shows how many items share the same file — a wrong photo on 42 items is found at once.
When the picture is right and the data is not
A white scanner with the colour attribute "anthracite" ends up in Review Image although the picture is right. Correct the attribute on the item then; the next run checks again.
When it runs
- For one item: marketplace item card → Draft Alt Texts with Copilot. The review then opens for that item.
- For the catalogue and new pictures: the alt text job queue entry, created in the setup. It runs every quarter of an hour, takes up to Pictures per Run pictures and continues on the next run. A picture is due when it has never been checked or its file changed. After three failed items in a row the run ends and tries again next time.
Setup
| Field | Meaning |
|---|---|
| Draft Alt Texts from Pictures | Switches the background job on. Off by default: the first catalogue run costs real money. |
| Picture Size for the AI (px) | The longer side pictures are scaled down to. Default 1024. |
| Picture Detail for the AI | High reads small print — which is what catches a wrong type number. Low costs a fraction. |
| Replace Existing Alt Texts | Off by default: pictures with an alt text are only checked for whether they fit and keep their sentence. |
| Accept Flawless Proposals Automatically | Off by default. Not recommended for the first catalogue run. Held-back pictures and sentences that broke a rule always wait for a person. |
| Pictures per Run | How many pictures one run of the job checks at most. |
Cost
Measured in the pilot with gpt-6-sol at 1024 pixels: about 0.3 cents per file for the analysis and around 0.8 cents per item for the fit check and writing. A new picture therefore costs about 1.2 cents, including the new sentences for its item. Every call appears in the AI usage log with model, picture count and cost, and counts against the token and the cost budget.