Gallery owner Pauline Bellamy said the past 20 years in the gallery had been amazing.
''It has not felt like work at all - more like an adventure.''
She and husband John opened the gallery in a garage in Greenacres St after she had a ''health scare'' with cancer.
''I decided I had to get into something substantial to take my mind off it. It made me look into the future and keep on going.''
The gallery quickly outgrew the garage and it moved to the Portobello Rd gallery in 1995 and the gallery floorspace had tripled in size, she said.
To celebrate the festival and the milestone year for the gallery the exhibition Swell includes work by herself and her husband and sons Manu Berry and Max Bellamy, and Max's partner, Emma Chalmers.
Her husband had made a relief print by using rough-sawn macrocarpa wood to mark abstract ink shapes on A2 paper.
''It's pretty exciting that he's involved because he's usually doing the framing for the rest of us.''
She is exhibiting oil paintings and etchings of Milford Sound after being inspired on a road trip to Fiordland with her husband about a month ago.
Max has an art installation video in the exhibition and photographs of Tautuku in the Catlins and abstract photos.
Emma Chalmers' work includes an abstract gouache seascape and Berry is exhibiting an abstract woodcut based on a spring blossom.
