Completed in April 1973, Chroma was commissioned by the Edward Johnson Music Foundation, with the help of a grant from the Canada Council, and was premiered as part of the Guelph Spring Festival on May 5, 1973, by the Orchestre symphonique de Québec under the direction of Pierre Dervaux. Clermont Pépin describes his work as follows:

Chroma (from the Greek «colours») is a display of tone colours, pulsations and rhythmic lines. From groups of pulsations stems a play of tone colours, of sinuous rhythmic lines, arranged in different fragments of varying length and grouped intro three large sections.

1) Sprays of Sounds. Dialogue between instruments or groups of instruments, outbursts of pulsations and clusters, division of the organisation of sound into irrational and approximate fragments. Some of these fragments include quarter tone motives played in a tempo left to the interpreter’s fancy.

2) Rhythmic Cannons. Counterpoints and mutations of rhythms, time-values and tone-colours, separated by long rests and stressed by the contrasting tone quality and the range of each instrument.

3) Post-Cannon. Conclusion of the two previous sections, with intermittent recalls of the sprays of sounds of the first section: pulsations, outbursts, dialogues. A commentary by the strings with a few brief interventions of the flutes and the harp completes the work.