Go To : Appearance > Customize > Header > Logo
Select Image or Text logo and specify other settings as per requirement.

Retina Logo

Based on retina.js
Optional. Can be enabled via customizer.

Go To : Appearance > Customize > Header > Logo
You will get retina logo image upload field once ‘Retina Logo Support’ enabled.

Needs to create two logo images

• 1st : Normal size [ logo.png ]
• 2nd : Double size with same name and @2x suffix [ logo@2x.png ]

Specify normal size and retina logo, in respective fields

Make sure you are uploading retina logo, if its support enabled. Otherwise it will give 404 error.

For extensive retina settings for images other than logo you could OFF this via customizer and activate any preferred plugin.