fill factor (image sensor)
The fill factor of an image sensor array is the ratio of a pixel's light sensitive area to its total area.
For pixels without microlenses, the fill factor is the ratio of photodiode area to total pixel area,
{{cite book
| url = https://books.google.com/books?id=K5aOhnvGJToC&pg=PA12
| page = 12
| title = Image Processing for Embedded Devices: From CFA Data to Image/video Coding
|editor1=Sebastiano Battiato |editor2=Arcangelo Ranieri Bruna |editor3=Giuseppe Messina |editor4=Giovanni Puglisi | publisher = Bentham Science Publishers
| year = 2010
| isbn = 9781608051700}}
but the use of microlenses increases the effective fill factor, often to nearly 100%, by converging light from the whole pixel area into the photodiode.
{{cite book
| url = https://books.google.com/books?id=K5aOhnvGJToC&pg=PA29
| page = 29
| title = Image Processing for Embedded Devices: From CFA Data to Image/video Coding
|editor1=Sebastiano Battiato |editor2=Arcangelo Ranieri Bruna |editor3=Giuseppe Messina |editor4=Giovanni Puglisi | publisher = Bentham Science Publishers
| year = 2010
| isbn = 9781608051700}}
Another case that reduces the fill factor of an image is to add additional memory beside each pixel, so as to achieve a global shutter on CMOS sensors.{{Cite web|url=http://www.personal-view.com/talks/discussion/2923/sensors-global-shutter/p1|title=Sensors: Global shutter - Personal View Talks|website=www.personal-view.com|access-date=2017-07-29}}
File:Additional_memory_to_achieve_global_shutter_effect_for_CMOS_sensor.jpg
