Dr Albert Theuwissen shares his thoughts on alternative functions for pixels and implemention

Dr Albert Theuwissen, Consultant at Harvest Imaging speaks exclusively with Image Sensors director Rob Stead in the lead up to his workshop at the 2014 Image Sensors Conference.

Q. We are pleased you are able to return to Image Sensors to deliver a workshop once again this year. How have you seen the event change over the years?

"Thanks. What I do see is a growth of the number of people attending the conference. I guess this is due to the improving organization and especially to the focus the conference is giving to the right subjects and topics in the rapidly changing landscape of image sensors. A new organization in a new technical field needed to find its way to the right people, and apparently after a couple of years, this is the case. More and more people involved in solid-state imaging associate London with the Image Sensors conference."

Q. Your workshop focusses on alternative functions for pixels - what are these potential functions?

"There are several examples such as: auto-focus pixels, light metering, digital zoom, implementation of high-dynamic range options, and several others. Of course they will be discussed during the workshop, advantages, limitations and implementation of these various functions will be explained in detail during the workshop, with lots of opportunity for discussion."

Q. What are the advantages of using pixels in a multifunctional way like this?

"In short, if you can implement these kinds of functions on the sensor itself, it will make the overall system more compact, less power hungry, faster, and last but not least much cheaper!"

Q. To what extent are these methods being implemented in commercial applications?

"If we look to the field of digital photography, then we do have products on the market that have auto-focus pixels implemented on the sensor focal plane. Also high dynamic range options are present in existing products. Digital zoom is very popular in mobile phone cameras because an optical zoom is very hard to implement, not to say impossible in a module for a mobile phone. That said, there are many more potential applications and I'm sure we'll implemented in the future."

Q. What are the challenges for commercial sensor producers developing multifunctional pixel arrays?

"For some of the applications, the multifunctional pixel needs a dedicated design (e.g. auto-focus pixels). For other applications these multifunctional pixels can have the same layout as all standard pixels, but then they need a dedicated way of reading the sensor or a dedicated way of processing the data delivered by the sensor. So, in some cases the challenges are shifted to the sensor designer, in other cases the challenges are shifted to the camera designer."

Q. And finally, who do you think would benefit from attending your workshop?

"By the incorporation of the multifunctional pixels on the focal plane, existing functionalities will improve (speed, power, cost), and new functionalities can be added to the sensor/camera. So the answer to your question could be: everyone who is interested in future developments of smart image sensors and cameras that employ these devices. Application fields will range from medical to mobile phone sensors/cameras, from machine vision to digital still sensors/cameras and depth of content will be suitable for relative newcomers and experts alike."