The referee handles general tournament organization, extraordinary situations on court, and also supervises the other technical officials. Tournament organization includes, among many others, basic scheduling, informing officials and team managers of any tournament-specific details, shuttle testing, checking that courts and equipment are in order, selecting and evaluating umpires etc. . At larger tournaments, there is usually one head referee and multiple deputy referees, working together as a team. The referee team is typically seated next to tournament control. Normally, referees wear red uniforms. Referees come on court in case of injury, significant disputes, and extraordinary misconduct.
Otherwise, the court and its surroundings is the domain of the umpire, clothed in black, and typically sitting on a high umpire chair. The umpire keeps track of the score, calls any faults (e.g. shuttle touching a player, or receiver moving too early) and lets (e.g. receiver not ready, shuttle from another court flying on court), and communicates with the players.
The service judge sits opposite the umpire on a normal chair. As the name indicates, he or she is mainly calling service faults so that the umpire can focus on the receiver. They also hand out new shuttles. Service judges are qualified umpires and thus wear a black uniform; umpires typically take turn in filling in either role.
For more information on the hand signals by the service judge, refer to §7 of the the Instructions To Technical Officials (ITTO). The ITTO also contain lots of guidance for the other officials.
Some large tournaments also had a third umpire per match who is manning the Instant Review System (IRS). When a player challenged a close line call, the IRS umpire made the decision, typically in an aside room or section away from court. These days, the IRS is usually fully automated.
Finally, the team of line judges is responsible for all line calls. At the top tournaments, umpires often fill in as line judges as well, but many international tournaments also have local volunteers. A line judge uniform is typically provided by the tournament organizer, often monochromatic blue or green. Two of the line judges - on at each side of the court - are also responsible for mopping the court in case of excessive sweat/dust/feathers accumulations.
The number of officials varies depending on the tournament importance. The full complement of referee, multiple deputy referees, umpire, service judge, 12 line judges and 2 mopper line judges is only reached at the very top tournaments (SuperSeries and Olympics). If officials are missing, their role is subsumed by another official. For instance, at national-level events, umpire and service judge often function as line judges for the lines they are sitting on, and one line judge presides over the back doubles service line, the back base line, and also mops the court if required. Depending on the tournament organization and/or national federation, shirt colors can also vary.