How did nineteenth-century painters respond to the intense competition that arose from the development of the hugely popular camera?

Because of the invention of photography, people no longer needed painters to depict realistic scenes. Therefore, art had to give people something that photography couldn't - and this was achieved in non-realistic paintings, for example, in impressionism. Claude Monet and Vincent van Gogh are good examples of impressionist painters as their paintings were not realistic but conveyed feelings - they were usually more dramatic than realistic paintings