Exam photo uploads

Three numbers that are not the same thing

A digital photo has a pixel size: how many dots wide and tall it is, such as 276 by 354. It has a file size: how many bytes it takes on disk, such as 38 KB. And it may carry a DPI value: a note in the file saying how many of those dots should be printed per inch.

They move independently. The same 276 by 354 picture can be 12 KB or 90 KB depending on how hard it is compressed. The same 38 KB file can say 72 DPI or 300 DPI without a single pixel changing. A notice that gives a size in centimetres is talking about pixels and DPI together: 3.5 cm at 200 DPI is 3.5 ÷ 2.54 × 200, which is 276 pixels.

The usual reasons a portal says no

• Too big in KB. A phone photo is 2 to 5 MB; the form wants under 50 KB. Shrinking the pixels alone often is not enough, because a large, sharp photo at high quality stays heavy.
• Too small in KB. Some portals also set a minimum, often 10 or 20 KB, to stop blank or broken uploads. An over-compressed photo of a plain background can fall under it.
• Wrong pixel size. Portals that check dimensions usually want them within a range, not to the pixel. Check whether the notice gives pixels or centimetres.
• Wrong format. Most want JPEG. A PNG renamed to .jpg is still a PNG inside, and a careful portal reads the bytes, not the name.
• A KB that means 1,000 bytes. Some portals count a kilobyte as 1,000 bytes, others as 1,024. A file of 50,500 bytes is 49.3 KB one way and 50.5 KB the other. Aim a little under the limit.

Meeting all three at once

Work in this order. First the pixel size, from the notice: if it gives centimetres, multiply by the DPI it states, or by 200 to 300 if it states none. Then the file size: lower the JPEG quality until the file fits, and only if quality has to go very low, make the picture slightly smaller instead. Last, write the DPI into the file, so a portal that reads it, or a person who prints it, sees the size the notice asked for.

The exam photo and signature resizer does exactly this for a photo and a signature together, with a pass or fail check against each form's range, and the KB resizer does the file-size step for any number of pictures. What DPI does and does not change is on the change DPI page.

What the photo itself needs

Size rules are checked by software; the photo is checked by a person, sometimes months later. Most notices ask for the same things: a recent photo, face centred and filling most of the frame, a plain light background, no shadows across the face, no dark glasses. A resizer cannot fix any of those, so check them before you start.