e g reach zero the palm and arm identifier 125 also may determine the perimeter of the selected blob by detecting where the capacitance readings drop below a particular threshold other than zero the palm and arm identifier 125 then compares the area of the selected blob to particular thresholds 325 and 345 if the area is above an upper threshold then the blob is labeled as likely corresponding to a resting body part 330 if the area is below a lower threshold then the selected blob is labeled as not likely corresponding to a resting body 350 for example the palm and arm identifier 125 may set the upper threshold as twenty square centimeters and a lower threshold at three square centimeters if the selected blob has an area of one square centimeter then it is labeled as likely not corresponding to a resting body part if the selected blob has an area of twenty five square centimeters then it is labeled as likely corresponding to a resting body part if the selected blob has an area of ten square centimeters then the selected blob proceeds to the next calculation in some implementations a confidence score is assigned to the blob where the confidence score reflects how likely it is that the selected blob corresponds to a resting body part in some implementations if the area is a percentage above the upper threshold then that percentage is translated into a confidence score if the area is a percentage below the lower threshold then that percentage is translated into a confidence score for example if the upper threshold is eight square centimeters then any blob with an area above that would be labeled as likely corresponding to a resting body part a different confidence score could be assigned to.