Instead of dancing at dub-reggae clubs, Grenada-born British artist Denzil Forrester makes sketches. “I go drawing at night and during the day I paint.” It started in the late 1970s, when Forrester began scribbling down images of D.J.s, dancers, and MCs, racing to get them onto A1 paper in the time it took the D.J. to play the track. The resulting works, which pulse with explosive energy, were named after the songs that inspired them. “Itchin & Scratchin,” a comprehensive show that has been touring for 40 years, displays these colorful renditions of British nightlife. —E.C.