The quick search engine allows you to use boolean operators to refine your search. By default, the search applies to all keywords. Searches are not case sensitive.
Here is a list of actions you can perform:
With keywords
Exact search
"george washington"
Use quotes to search for an exact keyword or phrase.
OR inclusive
john OR bill
Add an OR between words.
Exclude
george washington NOT bush
-george
Add a dash (-) or NOT before a word to exclude from search. Note that NOT acts as a filtering operator so you cannot have a search containing only NOT operators. You cannot combine OR with NOT (john OR NOT bill is not valid)
Grouping ()
(mother OR father) AND (daugther OR son)
Others
Supported numeric operators
=100 equals 100
>100 greater than 100
<100 less than 100
10..100 between 10 and 100 (inclusive)
..100 up to 100 (inclusive)
100.. from 100 and above
These operators can be used with numeric fields such as created:, posted:, width:, height:, size:, ratio:, hits:, score:, filesize:, id:.
tag:
tags:
tag:(john OR bill)
Searches only in tag names without looking at photo titles or descriptions.
photo:
photos:
photo:Tiger
Searches only for photos with the given words in title or description.
file:
file:DSC_
file:*.webp
Searches by file name.
author:
author:John
Searches by author.
created:
taken:
shot:
taken:2003 photos taken in 2003
taken:20035, taken:2003-5, taken:2003-05 photos from may 2003
taken:2003..2008 photos from 2003 to 2008
taken:>2008, taken:2008*, taken:2008.. photos after Jan 1st 2008
Searches photos by taken date.
posted:
posted:2003 photos posted in 2003
Searches photos by posted date. Same principle as for created:.
width:
height:
width:>500 return photos wider than 500px
height:<700 return photos less than 700px high
Searches photos with a given width or height.
size:
size:5m returns photos of 5 megapixels
size:>12m returns photos of 12 megapixels or more
Searches photos by size in pixels.
ratio:
ratio:3/4 OR ratio:4/3
finds photos from compact cameras in portrait or landscape modes
ratio:>16/9 finds panoramas
Searches photos by width/height ratio.
hits:
hits:>1000 return photos with at least 1,000 views
Searches for photos by number of views.
score:
rating:
score:* will give you all photos with at least one note.
score: will give you photos without notes.
Searches photos by rating.
filesize:
filesize:1m..10m finds files between 1MB and 10MB.
Searches photos by file size.
id:
id:123..126
finds photo 123 to 126 (it may find between 0 and 4 photos, because photos can be deleted)
Searches photos by its numeric identifier in Piwigo.
Trinity, Andreas Hellkvist 
Trinty i Vaksala Kyrka.