Every image going into Wan 3.0 has to sit inside three constraints at once:
None of them is unreasonable. Together they exclude a surprising amount of what a real project has in its assets folder.
Icons and favicons. A 128 px mark is under the floor. So is most of what a design system exports as "small".
Thumbnails pulled from a CMS. Content systems love a 200 px derivative, and that derivative is frequently what an integration grabs because it is the one in the API response.
Cropped faces. Someone crops a head out of a group photo to use as a character reference, and the crop comes out 190 px tall.
The last one is the expensive failure, because it happens at the moment the user is doing something clever. Upscaling is the fix, but it is worth being honest in the interface that an upscaled 190 px crop is a weak reference regardless of whether it passes validation.
The 8:1 window is generous for anything photographic. It is not generous for graphics:
The fix is padding, not cropping. Composite the wide asset onto a canvas that brings the ratio inside the window, with the background you actually want the model to read, and you have satisfied the validator without throwing away part of the asset.
8000 px is high enough that almost nothing hits it, with one exception worth naming: scanned and stitched material. Panoramas, poster scans, and anything that came out of a flatbed at 600 dpi. These also tend to blow the 20 MB cap at the same time, which at least produces two signals instead of one.
The habit worth building here is reporting every violated constraint at once rather than the first one you find.
An asset that is 190 × 2400 violates the floor and the ratio. A validator that stops at the first failure sends the user off to upscale, and then rejects the upscaled version for the ratio. Two round trips for one bad file, and the second rejection feels like the tool is moving the goalposts.
It is worth saying plainly that these numbers are not a quality judgement. A 240 px floor is not the model telling you the image is too small to be useful — it is a preprocessing constraint. Plenty of images that pass are still bad references, and the interface should not imply otherwise by treating validation as approval.
The more useful question, once an image is legal, is what the model will actually do with it: whether it becomes the literal first frame, or a style and identity hint the shot is composed around. Those are two different routes with two different sets of expectations, and what a starting photograph does and does not fix is the distinction worth getting right before you spend time resizing anything.
Dimension and ratio limits on this page were read from Alibaba Cloud Model Studio's Wan 3.0 API reference on 2026-08-25.