Portuguese visa photo requirements are the same as all Schengen visa requirements. 

You will need the following:

• Two photos that are not older than 6 months
• Photo size should be 35x45mm
• Photos should be in colour
• The applicant’s head should be at least 70% of the photo
• The applicant should look straight at the camera
• The applicant must have a neutral face expression (no smiles)
• If you wear glasses, avoid flash glare
• Avoid clothing matching the background

 Should you not match this criteria, it’s likely your application could be rejected. This could add delays and costs of your application.