A data collection device configured to be attached to, or releasably receive at least part of, a medicament delivery device, the data collection device comprising: at least two optical sensors, each arranged to detect light from a respective detection area; a processing arrangement; a display; and a camera; wherein: the optical sensors are configured to detect tick marks of a medicament dose indicator of the medicament delivery device in their respective detection areas; the camera is configured to capture an image of at least a part of the medicament dosage indicator; the processing arrangement is configured to: determine an initial medicament dosage displayed by the medicament dosage indicator by identifying at least one character or mark shown in said image; determine whether a current medicament dosage programmed into said medicament delivery device is increasing or decreasing, based on an order in which the optical sensors detect tick marks in said respective detection areas; determine a current medicament dosage programmed into said medicament delivery device based on the initial medicament dosage, a count of the tick marks that pass through the detection areas of the optical sensors during programming of said medicament dosage into said medicament delivery device and the order in which the optical sensors detect tick marks in said respective detection areas; and the display is configured to display the current medicament dosage in response to a change in the count. at least two optical sensors, each arranged to detect light from a respective detection area; a processing arrangement; a display; and a camera; wherein: the optical sensors are configured to detect tick marks of a medicament dose indicator of the medicament delivery device in their respective detection areas; the camera is configured to capture an image of at least a part of the medicament dosage indicator; the processing arrangement is configured to: determine an initial medicament dosage displayed by the medicament dosage indicator by identifying at least one character or mark shown in said image; determine whether a current medicament dosage programmed into said medicament delivery device is increasing or decreasing, based on an order in which the optical sensors detect tick marks in said respective detection areas; determine a current medicament dosage programmed into said medicament delivery device based on the initial medicament dosage, a count of the tick marks that pass through the detection areas of the optical sensors during programming of said medicament dosage into said medicament delivery device and the order in which the optical sensors detect tick marks in said respective detection areas; and the display is configured to display the current medicament dosage in response to a change in the count. the optical sensors are configured to detect tick marks of a medicament dose indicator of the medicament delivery device in their respective detection areas; the camera is configured to capture an image of at least a part of the medicament dosage indicator; the processing arrangement is configured to: determine an initial medicament dosage displayed by the medicament dosage indicator by identifying at least one character or mark shown in said image; determine whether a current medicament dosage programmed into said medicament delivery device is increasing or decreasing, based on an order in which the optical sensors detect tick marks in said respective detection areas; determine a current medicament dosage programmed into said medicament delivery device based on the initial medicament dosage, a count of the tick marks that pass through the detection areas of the optical sensors during programming of said medicament dosage into said medicament delivery device and the order in which the optical sensors detect tick marks in said respective detection areas; and the display is configured to display the current medicament dosage in response to a change in the count. determine an initial medicament dosage displayed by the medicament dosage indicator by identifying at least one character or mark shown in said image; determine whether a current medicament dosage programmed into said medicament delivery device is increasing or decreasing, based on an order in which the optical sensors detect tick marks in said respective detection areas; determine a current medicament dosage programmed into said medicament delivery device based on the initial medicament dosage, a count of the tick marks that pass through the detection areas of the optical sensors during programming of said medicament dosage into said medicament delivery device and the order in which the optical sensors detect tick marks in said respective detection areas; and the display is configured to display the current medicament dosage in response to a change in the count.