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equation:

abs(new_reading - calibrating_reading)/calibrated_reading * 100 = similarity




now using our numbers:


grey floor = (108 - 95)/95 * 100 = 13.7% different


white line = (108 - 112)/112 * 100= 3.6% different




compare: white line < grey floor


therefore the sensor sees a white line

if you wanted three different colors it would look something like this:

Set one straightened paper clip aside, you will use it at the
end. Bend the two tips of one of the two paper clips as shown.

Put it in through the fuse clip like this, but make sure the
notch in the fuse clip is facing out. (The clip has one edge bent inwards. This
is the part that has to face outwards). Study this next picture closely.

From the position above, bend the paper clip up and then
around the lead of the fuse clip as in the next picture.

Bend the paper clip under the fuse clip...

then up and over the fuse clip:

then around its other lead and you're almost done with the
first fuse clip.

First clip -- wire is on the RIGHT side of the fuse clip
leads...

Second Clip -- wire is on the LEFT side of the fuse clip
leads... But remember to make sure the notch in the fuse clip is facing out.
(The clip has one edge bent inwards. This is the part that has to face
outwards). 

Follow all the steps above with the second clip and you get
this: