ope this helps...

Photo Size should be between 10 Kb to 100 Kb
Photograph Size Photo Dimension allowed Size of photo: 35 x 45 mm (5 x 5 cm, 3.5 x 4.5 cm, 3.5 x 3.5 cm) 
Photograph Background should be White andand not use any other background 
Details on Photo are to be followed. Photograph having a white background with the clearly mentioned name of the candidate along with the date of taking photograph below must be used.
Photo must be taken on or after 1 Oct 2018.Photo should not have cap or goggles. Spectacles are allowed if used regularly.

Photographs will be mandatory and white background is must with name and date written on it. 

Size should be from 10kb to 100kb maximum if it smore you can compress it and upload. 

Jpg format photograph is required secondly. 

https://medicine.careers360.com/articles/neet-application-form