JPEG conversion fills transparency with white, not black

The browser converter paints transparent pixels white before writing JPEG because JPEG has no alpha; keep PNG or WebP to keep a hole.

Image Converter is a Canvas job on your machine. You pick PNG, JPEG, or WebP and a quality slider. When the target is JPEG, the tool fills the canvas #ffffff before it draws your image. Every formerly transparent sample becomes paper. That is not a quality setting and not a failed key. JPEG stores no alpha plane. Something has to occupy those pixels, and this converter chooses white instead of the black an unhandled canvas.toBlob("image/jpeg") usually writes.

JPEG has no hole to keep

PNG keeps an alpha channel. WebP can too. JPEG is YCbCr blocks plus a quality factor. There is no fourth channel, no matte, no "empty." A sticker, a logo with a cut-out, a product on a checkerboard — convert any of those to JPEG and the encoder must invent a colour for every sample that used to be a hole.

Most naive converters skip the fill. The browser composites onto a default black canvas. The logo arrives with a black halo, and someone spends an afternoon blaming the original PNG. The Versely converter paints white first, then draws. White is still a fill. It is a less surprising fill for slides, marketplaces, and anything that assumes a paper background. It is not transparency. If you needed a hole, you asked the wrong format.

The rest of the pipeline does not save you. Re-opening the JPEG in another editor and flooding white to transparent will also eat white in the subject — teeth, packaging, specular hits. The matte is gone. There is no undo. Keep the PNG.

White is a fill, not a background you can delete later

Once the file is written, those pixels are opaque white. The converter is honest about that: it is a local encode, not a model that "understands" a checkerboard. Nothing is uploaded. Network off, it still converts. Quality on JPEG and WebP is a size-for-artefact trade. PNG ignores the slider because PNG is lossless.

Image Compressor is the sibling when you have already accepted a fill and only want fewer bytes. Compression does not restore alpha. If a PNG got larger after a "compress," that is the lossless container adding overhead — change format to WebP if you still need the hole and a smaller file.

Remove the background from a photo is a different job entirely: a generate, billed in credits, driven by generate_image_from_image and a prompt such as "transparent backdrop." That can return a PNG with a hole. JPEG-ing that PNG afterwards is how a paid cutout becomes a white rectangle. Do the cutout last only if the delivery spec is JPEG-on-white. Do it first and keep PNG or WebP if you still need to composite onto a brand colour, a video frame, or a dark UI.

Do not prompt a catalog image row to "export this as JPEG but keep transparency." There is no such encode. You will spend credits on a new picture of a picture.

Keep PNG or WebP when the hole is the product

The converter's three targets are a decision, not a preference:

• WebP — usually the smallest at the same visible quality, and it can keep transparency. Use it for the web unless a downstream tool refuses the container.
• JPEG — the universal still. No alpha. White fill. Use it when the destination is email, a CMS that only takes .jpg, or print that will always sit on white paper.
• PNG — lossless, alpha intact, often smallest for flat logos and type. Keep it for stickers, overlays, and anything that will sit on a colour that is not white.

Pick the format from the destination, not from habit. A marketplace that rejects WebP is a JPEG job. A Recap overlay, a lower-third, a pack shot on a coloured card is a PNG or WebP job. The converter will not warn you that you just painted the hole; it will just write white.

The rest of the free tools shelf is the same class of work: File API, Canvas, on-device. Conversion is the one that looks like a harmless export and quietly fills the checkerboard.

Convert after you know the backdrop

Decide the backdrop first. If the asset will always sit on white — a marketplace thumbnail, a letterhead, a slide — JPEG with a white fill is honest and smaller than a 32-bit PNG of the same photograph. If it will sit on a colour you do not control, keep the hole.

If you already have only a JPEG of a cutout, this tool cannot recover the matte. Re-export from the PNG. If you no longer have the PNG, you are in image-editing, not conversion: a new generate, a new bill, a new chance to get the edge wrong. Text-to-image will not reconstruct an alpha plane you discarded.

A practical order: isolate the subject (generate, paid) → keep PNG/WebP → composite or deliver. JPEG is the last step, and only when the spec has already named a white (or paper) ground. The fill colour is #ffffff. There is no picker for brand cream, no "match the slide." If you need a custom matte, you are drawing one, not converting.

FAQ

Why white instead of black?

Unhandled canvas-to-JPEG usually composites onto black. Logos then grow a black fringe that looks like a failed key. This tool fills white first so the accidental colour is paper, not a void. It is still a solid colour. If you needed empty pixels, do not pick JPEG.

Will WebP keep my transparency?

Yes, when you pick WebP as the target. WebP encodes alpha. JPEG does not. The converter only paints white when the selected type is image/jpeg. PNG keeps the hole as well, lossless.

Can I pick a different fill colour?

Not in this tool. The JPEG fill is #ffffff, and PNG/WebP get no fill. A custom matte is a different editor job — draw it, or composite onto the colour you actually need, then encode.

Should I JPEG a generated cutout to save credits?

No. Conversion is free and local. Credits were already spent on the cutout. Encoding JPEG does not refund anything; it only destroys the alpha you paid to get. Keep the PNG until the delivery spec names JPEG-on-white.