hello im willing to use the QTR-8A sensor array to detect white line on different color back ground
is it possible ?

any consideration shall i take with the Arduino library ?

Thank you


What will probably be more important than the color is the difference in the IR reflectivity between the two colors. As long as your white line is significantly more reflective than the background color, it should work (black usually works well as a background color). You should not need to modify the Arduino library at all.


there is blue ,red and green back and there is whitish blue i think its going to be the problem

its ACI is 4 (automatic cad color index )


The automatic cad color index you mentioned is for the visible light spectrum and will have no real bearing on its IR reflectance. Although you will probably be able to distinguish between white and some other color, you may not be able to tell the difference between colors such as green and blue. These sensors are only capable of sensing the amount of IR light reflecting from a surface.


what im understanding now … that i will be able to detect my white line whatever the background is
am i right ??and there is no need to modify the code

You should not need to modify your code. However, you may not be able to detect a white line on a nearly white background such as the whitish-blue color you mentioned earlier. More importantly, what you see with your eyes might not correspond to what the sensor detects. If the background is glossy yellow and reflects a lot of IR light and your line is a matte white, it is possible the background could reflect more IR light than the line. In general, if you stick to high contrast colors with similar surface characteristics (e.g. matte or glossy) you should have good results with this type of sensor.


the sensors work pretty well with White and black

other than those colors its so close to white color reading it feels too bad actually :frowning:
and the calibration is a miss with readings so close to each other