Apparatus for use with a blood sample and an output device, the apparatus comprising: a microscope system configured to acquire: a first image of the blood sample, and a second image of the blood sample, there being a time interval between acquisitions of the first and second images; and a computer processor configured to: identify an entity within the first image that is disposed in a vicinity of an erythrocyte, and which has dimensions that indicate that the entity could be a platelet or could be an intra-erythrocytic parasite, by analyzing the first image of the blood sample, based upon identifying the entity: select to compare the first and second images of the blood sample to one another, and determine that the entity is a platelet, by identifying relative motion between the entity and the erythrocyte between the first and second images, and perform a complete blood count or part of a blood count, which includes a count of platelets, using as data the determination that the entity is a platelet, and generate an output in response to the count performed. a microscope system configured to acquire: a first image of the blood sample, and a second image of the blood sample, there being a time interval between acquisitions of the first and second images; and a first image of the blood sample, and a second image of the blood sample, there being a time interval between acquisitions of the first and second images; and a computer processor configured to: identify an entity within the first image that is disposed in a vicinity of an erythrocyte, and which has dimensions that indicate that the entity could be a platelet or could be an intra-erythrocytic parasite, by analyzing the first image of the blood sample, based upon identifying the entity: select to compare the first and second images of the blood sample to one another, and determine that the entity is a platelet, by identifying relative motion between the entity and the erythrocyte between the first and second images, and perform a complete blood count or part of a blood count, which includes a count of platelets, using as data the determination that the entity is a platelet, and generate an output in response to the count performed. identify an entity within the first image that is disposed in a vicinity of an erythrocyte, and which has dimensions that indicate that the entity could be a platelet or could be an intra-erythrocytic parasite, by analyzing the first image of the blood sample, based upon identifying the entity: select to compare the first and second images of the blood sample to one another, and determine that the entity is a platelet, by identifying relative motion between the entity and the erythrocyte between the first and second images, and select to compare the first and second images of the blood sample to one another, and determine that the entity is a platelet, by identifying relative motion between the entity and the erythrocyte between the first and second images, and perform a complete blood count or part of a blood count, which includes a count of platelets, using as data the determination that the entity is a platelet, and generate an output in response to the count performed.