Using Wikidata Query Service

Wikidata has a query service with examples like cats, with pictures

#Cats, with pictures
#defaultView:ImageGrid
SELECT ?item ?itemLabel ?pic
WHERE
{
?item wdt:P31 wd:Q146 .
?item wdt:P18 ?pic
SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en" }
}

The first line is read as 4 components:

• ?item means
• wdt:P31 means “instance of”
• wd:Q146 . means
• wdt:P18 means

The first step to finding images I want is to go backwards and inspect the properties of an image found already (from the Commons: Featured pictures link above)

• An example of such a picture is Scheme of a submarine eruption
  • This is a SVG but every SVG has a PNG (e.g. here it's this 1080x1080px PNG)
  • Clicking "More details" gives the details page
• The property for a Wikimedia Commons featured picture is Q63348049