An ID photo is a crop, a size and a background — and photo shops charge for all three. Start from a picture you already have, drag it into the frame against the head and eye guides, pick the standard you have been asked for, and save it at 300 dpi. There is also a sheet layout that fills a single 4×6 print with as many copies as will fit, so a print shop charges you for one photo instead of a set.
The size, the resolution and the background will be right; the pose is on you. Authorities reject on things this tool cannot check — a smile, hair across the eyes, glare on glasses, a shadow behind the head, a picture more than six months old. Get the source picture right and the crop here will not be what fails it.
Because it is what print needs. A 35×45mm photo at 300 dpi is 413×531 pixels, and anything less is visibly soft once it is on paper at that size. Screens do not care, but the photo you print does, and the same file works for both.
A photo shop charges per print, not per face. One 4×6 print holds six 35×45mm photos with room to cut between them — or nine of the smaller 30×40mm size — so you pay for a single picture and come away with a set. The button tells you how many the size you picked will fit, the sheet is laid out whichever way round the paper holds more, and hairline cut guides are printed around each copy. It is the same file whether you print it at a shop kiosk or at home.
No. The picture is read into a canvas element in this tab, and every crop, colour change and export happens there. Nothing is sent to a server, which is worth caring about when the photo is going onto an identity document.
That is the limit of what a colour-based fill can do — it can tell a wall from a face, but individual strands sit somewhere between the two. Lowering the sensitivity keeps more of your hair at the cost of leaving more of the wall. If the result still is not clean, the background remover on this site separates subject from backdrop properly; run the photo through it, then bring the transparent PNG back here to crop and size it.