Make a picture transparent

An ordinary photograph is three numbers per pixel: how much red, how much green, how much blue. A transparent PNG is four. The fourth runs from nought to two hundred and fifty-five and means opacity — nought is a pixel that is not there at all, two hundred and fifty-five is a pixel that is entirely there, and everything between is a pixel that is partly there, which is what a strand of hair or the edge of a shadow actually is.

Nothing displays a fourth channel directly. Every program that shows you the file picks something to put behind it and blends. A browser uses the page. An image viewer usually uses a checkerboard so you can see the channel is doing something. A word processor almost always uses the paper. None of them is wrong, and none of them is looking at a different file from the others.

The backing swatches on step 3 are the reason this page is worth using over one that just hands you a file. A cutout checked only against a checkerboard hides two faults: a pale fringe, which disappears into the light squares, and a dark one, which disappears into the dark squares. Put the cutout on near-black and a pale halo becomes obvious instantly; put it on paper and a dark rim does the same. Neither swatch is written to the file — it is a light held behind the work, and the export panel offers exactly one thing regardless of what you were looking at.

The other thing worth doing before you save is turning feather down to nought for a moment. A soft edge flatters everything; a hard one shows you precisely where the boundary was decided, including the places it was decided badly. Fix those with the brush, then put the feather back.

Is transparent the same as white?

They are opposites, and confusing them is the single most common thing that goes wrong with these files. White is a colour a pixel has. Transparent is a pixel having no colour of its own and letting whatever is underneath show instead. A cutout on white looks identical to a cutout on transparency until you put it on a coloured slide, at which point the white one arrives inside a rectangle.

Which formats can actually hold it?

PNG holds it properly and is what this page writes. GIF has a crude version — one colour in the palette is nominated as see-through, so an edge is either fully there or fully gone and anything soft goes jagged. WebP and AVIF hold it well and are handled inconsistently by the places people paste. JPG has no alpha channel of any kind, so re-saving a cutout as a JPG is a one-way loss.

I need a white ground for a form that rejected my photo.

Then transparency is not what that form wants and this is not the page for it. A portal asking for a plain white ground is asking for a colour to be present, not absent, and a transparent PNG sent to one usually arrives as a black rectangle because of how the form flattens it. That is a different job from the one here.

Does making it transparent make the file smaller?

Generally the opposite. PNG-32 carries a fourth channel and compresses without loss, so a photographic subject saved this way is often larger than the JPG you started from. The tight crop on step 4 is the lever that matters — a cutout trimmed to its own bounding box can be a fraction of the frame it came out of.

• Why a transparent PNG can still look whiteTransparency is a channel, and every app you paste into decides what sits behind it.
• Cut out hair and furA wider uncertain band and a softer ramp, set that way before you arrive.
• Lift a signature off a scanInk on paper, measured against the paper rather than mistaken for an object.
• Hair, fur and every other soft edgeWhat the uncertain band is, what widening it costs, and the edges nobody wins.