Patent ID: 7736588

Claim:
A detection arrangement for detecting presence of a residue in a sample in relation to a threshold value of a selected composite parameter Z, wherein the detection arrangement comprises: a processor, a memory, a display, and a scanner, said memory, said display and said scanner being arranged to communicate with said processor, said scanner being arranged to generate light signals, to send said light signals to said sample, to receive reflected light signals back from said sample, to convert said reflected light signals into color signals and to send said color signals to said processor, said processor being operated by instructions stored in said memory and being arranged to display at least one color value on said display in accordance with said color signal, said at least one color value being associated with an L*a*b color model, wherein said processor calculates a value of a composite parameter Z in response to said instructions in accordance with a following equation: Z=w L ·L+w a ·a+w b ·b wherein w L , w a , and w b , are weighting factors indicative of residue concentration in a selected range, wherein w L , w a , and w b , are not identical to one another and w a , and w b , are between 0.1 and 0.9, and wherein the weighting factors w L , w a , and w b , are calculated by discriminate analysis and the composite parameter Z is calculated for optimal power of discernment, and wherein said processor determines whether or not the calculated composite parameter Z is more or less than the threshold value of the selected composite parameter Z to thereby determine the presence or absence, respectively, of the residue in the sample, and wherein said processor as operated by said instructions, calculates at least an absolute or a relative quantity of said residue in the selected range in said sample in dependence on said value of said calculated composite parameter Z.