What background colour does a passport photo need?
Almost every country requires a plain, light background — India's Passport Seva asks for a plain white or light-coloured background, and the US asks for white or off-white. A photographed wall with shadows or colour cast is the usual reason for rejection; a digitally applied flat white passes.
Requirements differ in size, not much in colour: India uses 2×2 inches (51×51 mm) for Passport Seva and 35×45 mm for most other forms; the US uses 2×2 inches; Schengen visas use 35×45 mm. Always check the current guideline for the specific application before you print.
Get the colour right first, then crop: remove the background on bgclear, choose White in the editor, download, and crop to the required size in your phone's photo app. The passport-size photo guide (also in Hindi) has the steps and the common rejection reasons.
Some forms specify light blue instead — certain Indian exam and bank portals, school IDs and a few national ID systems abroad. The passport photo background page covers which blue to use (a flat light blue such as #C6E0F0, never a photographed cloth) and how to apply it with the editor's swatch or custom colour picker.