Increased Dynamic Range

The promise of near-limitless highlight capture

The poor dynamic range found in normal cameras that so restricts the quality of stained glass window photography was the primary obstacle I had to overcome in my research.  However, a recent publication by German researchers from the Institut für Mikroelektronik Stuttgart (HERE) reveals a pixel design for massively increased dynamic range.

Existing CMOS chips ‘clip’ when they become saturated with light.  However, their ‘self-resetting pixel’ resets and has a circuit that counts how many times it has had to reset during the exposure.  It also contains a conventional analogue-to-digital conversion circuit, so it is also able to measure the remaining charge at the end of the exposure.

Such technology would mark an end to the need to limit exposure to protect highlight data.  Instead, optimal exposures for capturing the subject could be set, safe in the knowledge that this will not result in blown-out highlights.


Realised CMOS tests chip: (a) the packaged chip, (b) the layout

Currently the work is focussed on video for industrial applications and is at a fairly early stage.  However, it should be transferable to still photography and would greatly improve the dynamic range of cameras, making it easier to photograph the interior of a church while maintaining the vibrant appearance of the stained glass windows.

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