Why tweak (modify) Piwigo?
By default Piwigo has a lot of functionality, which can be extended by freely available plugins. The layout of Piwigo photo galleries can be changed by selecting another theme. It is possible that this is not enough for the purpose you have for your photo gallery. In my case I missed:
- the lack of display of all metadata (EXIF, IPTC, XMP) I enter in Adobe Lightroom, but was not visible next to my photos in Piwigo.
- a nice and clear layout
So I started tweaking Piwigo.