Why check before you upload
Most rejections are not mysterious. A file is a few kilobytes over the ceiling, or it is a PNG where the portal wants a JPEG, or it is an iPhone HEIC that was renamed to .jpg and never actually converted. All of those are visible in the file itself before you go anywhere near the application form, and all of them are quicker to find here than to discover from an error message at the end of a long form.
The reason to check rather than simply resize is that resizing a file that is already correct can only make it worse. Every JPEG save loses a little detail, so if the photograph a studio gave you already lands inside the window there is nothing to gain by re-encoding it. This tells you which situation you are in.
What is checked, and what cannot be
Four things are measured, and each is reported against what the notification asks for:
- Format. Read from the file’s own signature bytes rather than its name, because renaming a HEIC to
.jpgchanges nothing about its contents. This is the check that catches the most confusing rejections, since the file looks like a photo everywhere except the portal. - File size. Against both the floor and the ceiling. Portals disagree on whether a kilobyte is 1000 or 1024 bytes, so the window used here is the overlap of both readings and a file that passes will pass either validator.
- Dimensions. Exactly as the body states them, which differs more than you would expect: some give one fixed size, some a window that applies to both sides, some independent bounds per side, and some only a print size in centimetres.
- Shape. Kept separate from dimensions, because a file can be inside every pixel bound and still be the wrong proportion. Where an exam states the allowed ratio, as GATE does, being outside it is a failure. Where the ratio is only implied by a print size, a small deviation is flagged as worth knowing rather than called a rejection.
What cannot be checked is the picture. No tool can see whether the background is plain, the face is unobscured, the light is even, or the photograph was taken this year rather than five years ago, and every one of those is a documented reason for refusal. A pass here means the file is technically correct, which is necessary and not sufficient.
One photo, several exams
Candidates rarely apply to a single exam in a season, and the requirements almost never match: the same face has to arrive as 200 by 230 pixels for one body and somewhere between 200 and 530 pixels wide for another. Add your file once and change the exam in the selector, and it is re-checked against the new rule straight away, so you can see at a glance which applications you already have a usable file for.