surface is above the dew point in the sample cavity 21 after the condensation surface has been heated an initial reference image from the imaging system is being delivered to the analysis system 22 amp 23 this initial image is used to define the location of the condensation surface within the image by applying an analysis algorithm for example an edge detection algorithm 24 the edge detection algorithm operates by defining deviations in the brightness reading for each pixel within the generated image the brightness level of each pixel is described using an 8 bit greyscale a pixel that is receiving no light and is completely black has a greyscale value of 0 while a pixel that is saturated with light and is completely white has a greyscale value of 255 once located 25 the perimeter of the condensation surface is geometrically defined and the area inside the perimeter of the condensation surface is defined as the region of interest roi for all subsequent analysis 26 immediately following the definition of the roi a reference image of the region is stored in the system memory for subsequent comparison 27 once defined the roi of subsequent images is analyzed using an analysis algorithm for.