The invention provides an improved method for sensitive and specific detection of target molecules, cells, or viruses. The inventive method uses large area imaging to detect individual labeled targets complexed with a target-specific selection moiety. The invention eliminates wash steps through the use of target-specific selection through one or more liquid layers that can contain optical dye and density agents. By eliminating washes the invention simplifies instrumentation engineering and minimizes user steps and costs. The invention uses sensitive image analysis to enumerate individual targets in a large area, is scalable, and can be deployed in systems ranging in complexity from manual to highly automated.
