This paper describes camera based systems and image processing technique as a monitoring tool for farm animals. Image based systems were used to automatic measure the activity and occupation indexes of piglets and broilers chickens. Experimental results were presented in a form of two case studies: 1) Understanding the effect of environmental enrichment in piglet’s activities - the study was conducted in two selected pens of a fattening room. The activity of 14 Dalland piglets was recorded continuously for a total of 5 days. On the second day environmental enrichments were introduced in the form of two wooden logs and a chain. 2) Understanding the effect of light intensity on broiler chicken’s activities - in a total of 62 Ross 308 broiler chickens (equal number of female and male) kept on a 16 h photoperiod treatments. The light intensity schedule varied according to the age of the chickens. For chickens with 15 days old the light-dark schedule alternate every 4 hours between 5 lx and 100 lx. For chickens with around 21 and 40 days old the light conditions alternated every 2 hours. In both study cases the activity index recorded the total amount of movement at a group level. Piglets increased their movements and playing behaviour when environmental enrichments (wood logs and chain) were introduced to the pens. Broiler chickens showed higher activity indexes during periods of 100 lx than 5 lx when light intensity alternated. ; status: published