Check the real image format when a background remover rejects HEIC, GIF, SVG or a file with a misleading extension.
Read what the tool accepts
ToolNivo's background remover accepts JPG, PNG and WebP. Other formats need conversion before selection. A photo from a phone may be HEIC even if it looks like an ordinary photograph in the gallery. A graphic downloaded from a website might be SVG, GIF or even an HTML page rather than one of the supported raster formats.
Convert the contents, not the name
Open the original in an application that supports it and export a supported format. Renaming picture.heic to picture.jpg does not change the encoded image. Likewise, adding .png to a webpage does not make it a picture. After conversion, reopen the new file locally and verify its dimensions and appearance.
For an animated GIF, decide which single frame you actually want. The background remover is for a still image; it does not process an animation frame by frame or export an animated transparent result.
Protect existing quality
Keep the original and avoid screenshots when a proper export is available. If the image already contains transparency, prefer an export that preserves it. Check file size and pixel limits after conversion because PNG may occupy more storage than the original format. Once the supported image opens successfully in the tool, inspect the original preview before starting removal so a conversion problem is not mistaken for an AI masking error.