An assay reader system incorporating a conventional assay reader, for example a lateral flow reader, and an insert aligned with the reader’s sensor to detect an assay result. Certain novel coated substrates, such as flakes, spheres and porous substrates are disclosed. This compressed bitstream can then be provided to a separate decompression engine that selectively decodes portions of the compressed bitstream based on an access request for image data associated with a desired view from a rendering engine.