Opacity is its own picture
A PNG carries four numbers per pixel, and the fourth — how opaque the pixel is — matters as much as the colour when the words sit over the edge of a sticker or across a cut-out. Filling colour alone over a transparent area paints solid pixels where there should be none; filling opacity with the colour fill smears it. This route rebuilds the opacity by diffusion and the colour with the fill you pick, and puts them back together.
Where this mode goes wrong
- Words that are the only thing in the picture.With nothing around them, there is no edge to continue; the area comes back transparent.
- Detailed or curved edges under the words.Hair, fur or a curved outline under long lettering is continued as a smooth guess, not traced; keep Letters only and check the edge at 1:1.
- Saving as JPG.Transparency is lost in JPG by definition; the page warns before you do it.
What stays on this device
The PNG is decoded and cleared in this tab and written back by your browser. Nothing is uploaded or stored.
Questions about PNG files
Is transparency kept?
Yes. Every pixel's opacity is read from the file, and inside the cleared area it is rebuilt on its own by diffusion from the opacity around it. Outside the cleared area, colour and opacity come back byte for byte. The stage shows a checkerboard behind see-through pixels so you can see the result before saving.
Why not save as JPG?
JPG has no transparency: every see-through pixel would be written as solid black. This route opens with PNG selected, which keeps every level of opacity; WebP keeps transparency too and is offered where your browser can write it.
What happens at semi-transparent edges?
Colour is rebuilt on premultiplied values — each pixel's colour weighted by its opacity — and then divided back out by the rebuilt opacity. A half-transparent edge pixel therefore contributes half its colour and a fully transparent one none, so the fill does not drag a grey or black fringe in from the empty areas.
How is lettering found on a transparent picture?
Black letters on a transparent background have the same colour bytes as the background; only their opacity differs. For finding and masking, the picture is read as if laid over mid grey, so both dark and light letters stand out. The fill itself works on the real pixels.
Where the job goes next
- Screenshots, by the folder Flat ground and sharp edges, PNG in and PNG out, and the queue for a set of frames is on by default.
- Remove text from a JPG Saved back at the quality the file was made at, read from its own tables, with the size before and after.
- ImageTextRemover Draw a box over the lettering, keep the boxes you meant, and get the picture back with the ground painted across them.
