Much higher quality images are available on the NASA Image Library:

Dark Side of the Earth: https://www.nasa.gov/image-detail/amf-art002e000193/

Hello World: https://www.nasa.gov/image-detail/fd02_for-pao/

On images-assets.nasa.gov, we can find the 5567x3712 resolution versions of these pictures:

Dark Side of the Earth: https://images-assets.nasa.gov/image/art002e000193/art002e00...

Hello World: https://images-assets.nasa.gov/image/art002e000192/art002e00...