Born in 1932 in Quebec, Dumas has always been a man of visual communication. From the age of seven he practiced art, mastering perspective and drawing his environment with a sure hand.
As a teenager, his drawings were identified by English scripts or large serif capitals. His interest in letters is still evident during his years of teaching when his grade tables are displayed with beautiful handwritten letters to the delight of his students.
Passionate about new knowledge, Dumas made his first long trip to Europe before entering the School of Fine Arts in Quebec in 1954. By bringing his sketchbook with him, he developed his plastic sense. Already, he displays the main characteristics of his style: graphic schematization, sense of anecdote, strongly structured composition and profusion of light and color. His work holds a critical discourse on society. It is characterized by the use of large areas and luminous colours as well as an attention to detail which highlights a main idea, an emotion, a message.
Dumas is a man of images, it is his way of expressing his ideas. He graduated in 1958 while holding two careers, that of a painter and of a graphic designer at the largest advertising agency in Quebec. He then established himself on his own and actively worked as an illustrator. He held his first solo exhibition in 1968 and the Musée du Québec opened its doors to him for a traveling exhibition in 1973. He taught at the École des beaux-arts from 1960 and became a career teacher there two years later.