If the tool sent your photo back with a note about the background, one of three things happened. All three are fixed by moving, not by editing.
A shadow on the wall behind you
This is the most common one by far. You were standing too close to the wall, or a lamp was above and behind you. Document offices treat the background as a surface that must be one flat, even colour, and a shadow is a second colour.
The fix: step about a metre away from the wall and turn so the light comes from in front of you. We replace the background colour itself, but a shadow sits on you as much as on the wall, and removing it would mean repainting the edge of your face.
The background is not plain
A bookshelf, a curtain, a doorframe, a second person walking past — anything with an edge in it confuses the cut-out exactly where it matters most, around the hair. The result looks acceptable when small and falls apart when the office prints it.
Find a plain wall, or stand further from whatever is behind you so it falls out of frame.
Your head or shoulders are cut off
The frame was too tight. Every specification fixes how much of the head must fill the picture, and we can crop inwards but never outwards: the pixels above the crown simply do not exist. Step back, leave a hand's width of space above your head, and include the top of your shoulders.
How many tries do you get?
Re-uploading is free. You can replace the photo on the same order five times before we put it on hold and ask you to write to us, so there is no cost to trying again with better light.
Nothing is charged until a photo has passed the checks, and the preview you see before paying carries a watermark — so you always know what you are buying. If you think a check is wrong about your photo, contact us with the order number and a person will look at it.