Patna Kalam is regarded as an off-shoot of Mughal painting, with influences from Persian and Company (British) styles. The portraits can be clearly seen having colours and linings from Mughal style, and the shading can be seen to be adopted from the British style. Diverging from the Mughal and Persian style of wide and exquisitely decorated borders, Patna Kalam primarily focused on the subject of the painting.
Unlike Mughal painting, which focused on the royalty and court scenes, flag bearers of Patna Kalam were deeply influenced by daily life of common man. Their main subjects were local festivals, ceremonies, bazaar scenes, local rulers, and domestic activities. The paintings were done on diverse surfaces such as paper, mica, and even ivory diskettes, that were used as brooches.
Tamtam (Horse drawn carriage) -by Shiv Lal
A distinguishing characteristic of Patna Kalam is lack of any landscape, foreground or background. Another characteristic was the development in the shading of solid forms. Patna Kalam paintings are painted straightway with the brush without marking with pencil to delineate the contours of the picture and the procedure of painting is popularly known as 'Kajli Seahi.' Wikipedia