Assay reading method

A computer implemented method for reading a test region of an assay, the method comprising: (i) providing digital image data of a first assay 201; (ii) inputting the digital image data into a trained convolutional neural network (Figure 6, 602) configured to output a first probability, based on the input digital image data, that a first region of pixels of the digital image data corresponds to a first test region of the assay; (iii) if the first probability is at or above a first predetermined threshold, accepting the first region of pixels as a first region of interest associated with the first test region (Figure 6, 603): and (iv) estimating an intensity value of a portion of the first test region in the first region of interest (Figure 6, 604). There may be a plurality of test regions in a single image and the test regions may be not be aligned parallel one another. The assay may comprise a housing and may be a lateral test flow device. Further disclosed is an associated apparatus, computer program and computer readable storage medium.