Initially there is nothing of much worth. Basically a normal webcam has two parts one is: The PCB part with the CMOS sensor. (Exactly the PCB has a CMOS sensor mounted on it which receives the image from the lens and it projects a very tiny image on the CMOS.)The other part is the lens which receives the picture from the front side and the makes it very small at the other side so that it can be projected at the CMOS sensor. Now what we are doing right now is we just invert the lens (means upside down) and now install it on the CMOS sensor back again. Now the smaller side of the lens receives the image form outside and the bigger side projects it on the CMOS sensor.In this case the inverse happens the smaller side of the lens magnifies the image (which is outside or the object under observation) to a big level and the projects the magnified image to the CMOS sensor. This is the whole concept. Well what i used in this project is a bus security camera but now you know the concept it can be still applied in any camera or even webcam having a detachable lens.Though good camera has a good quality image but still you can use a cheap camera too.



IMPORTANT: Now there are two factors on which the quality of the image depends these are:



Distance of the object under observation from the outer or the smaller side of the lens.

This is the most important factor if the distance will be more the image will be inverted and if it will be too close the image will be blurry. So it's important to keep a perfect distance you can yourself adjust it according to you to get a good image.

Light

There should be a proper light to watch the object this is also an important factor the lower the light the worse is the image quality.

Quality of the camera

The better the quality the better the image.