An activity recognition device, the device comprising: a port configured to receive a video stream from a video source configured to provide video of an interior view of a vehicle operated with at least one occupant in the vehicle's cabin, so that the video stream includes image frames of at least a first object and a second object present in the cabin, wherein the first object comprises a hand of the at least one occupant and the second object comprises an object other than the hand with which the hand is interacting; a memory configured to store instructions and the image frames of the video stream; and one or more processors, wherein the one or more processors execute the instructions stored in the memory, characterized in that the one or more processors are configured to detect a global area of interest, ROI, based on presence of the first object by detecting the first object in the image frames by recognizing features that represent a human hand in each respective image frame, wherein the ROI contains at least one detected hand area and at least one object surrounding the hand area within a range of the hand area, and wherein the ROI is a selected portion of the respective image frame; determine an activity active area, AAA, within the selected portion of a respective image frame, wherein a location of the first object in the respective video frame is bounded by the determined AAA, and wherein the AAA is recurrently sized to have minimum window size still completely including an image of the hand; determine motion of the first object, by tracking its location in a previous, first image frame versus a current, second image frame, and locations of the second object within the AAA of the image frames; and identify an activity according to the determined motion and locations of the second object, and generate an alert according to the identified activity. a port configured to receive a video stream from a video source configured to provide video of an interior view of a vehicle operated with at least one occupant in the vehicle's cabin, so that the video stream includes image frames of at least a first object and a second object present in the cabin, wherein the first object comprises a hand of the at least one occupant and the second object comprises an object other than the hand with which the hand is interacting; a memory configured to store instructions and the image frames of the video stream; and one or more processors, wherein the one or more processors execute the instructions stored in the memory, characterized in that the one or more processors are configured to detect a global area of interest, ROI, based on presence of the first object by detecting the first object in the image frames by recognizing features that represent a human hand in each respective image frame, wherein the ROI contains at least one detected hand area and at least one object surrounding the hand area within a range of the hand area, and wherein the ROI is a selected portion of the respective image frame; determine an activity active area, AAA, within the selected portion of a respective image frame, wherein a location of the first object in the respective video frame is bounded by the determined AAA, and wherein the AAA is recurrently sized to have minimum window size still completely including an image of the hand; determine motion of the first object, by tracking its location in a previous, first image frame versus a current, second image frame, and locations of the second object within the AAA of the image frames; and identify an activity according to the determined motion and locations of the second object, and generate an alert according to the identified activity. detect a global area of interest, ROI, based on presence of the first object by detecting the first object in the image frames by recognizing features that represent a human hand in each respective image frame, wherein the ROI contains at least one detected hand area and at least one object surrounding the hand area within a range of the hand area, and wherein the ROI is a selected portion of the respective image frame; determine an activity active area, AAA, within the selected portion of a respective image frame, wherein a location of the first object in the respective video frame is bounded by the determined AAA, and wherein the AAA is recurrently sized to have minimum window size still completely including an image of the hand; determine motion of the first object, by tracking its location in a previous, first image frame versus a current, second image frame, and locations of the second object within the AAA of the image frames; and identify an activity according to the determined motion and locations of the second object, and generate an alert according to the identified activity.