Ams High-sensitivity Optical Sensor Eliminates Flicker Artifacts

ams, a worldwide supplier of high-performance sensor
solutions, has introduced a sensor solution that enables smartphone
world-facing cameras with rolling shutter image sensors to eliminate unwanted
image artifacts - such as banding - that are caused by the flickering of
artificial light sources.

With the wide-spread usage of LED lighting, photography
increasingly suffers from what is known as flicker from the lighting source.
The higher accuracy and sensitivity of the new TCS3408 color sensor, which
measures the color and brightness of ambient light as well as detecting photometric
flicker, enables a phone's camera-enhancement imaging system to eliminate
flawed artifacts caused by artificial lighting environments. It delivers the
industry's highest level of on-chip ambient-light flicker sensitivity, which is
three times greater than the prior generation TCS3707.

David Moon, Senior Product Marketing Manager in the
Integrated Optical Sensors business line at ams, says: “The increasing pixel
count of today's high-resolution smartphone cameras enables image capture with
extraordinary detail and clarity, however pictures and videos can often be
ruined with unsightly banding distortion effects from flickering light sources.
Smartphones can now capture vibrant, detailed and artifact-free images in all
lighting conditions, thanks to the TCS3408 high-sensitivity flicker
sensor.”

Color sensing for the real world

Mobile phone cameras today typically use basic three-channel
Red/Green/Blue (RGB) sensors to approximate color balancing in the image
enhancement system, and have no means of measuring flicker detection. The
TCS3408, with on-chip flicker detection, provides an accurate measurement of
color and brightness thanks to five concurrent-reading ambient light sensing
channels - a wideband and a clear reference channel in addition to the RGB
channels. The TCS3408 also provides an option to store a sequence of flicker
measurements in its internal memory to allow the smartphone's camera's video
processor to detect higher-order flicker frequencies up to 2kHz.These flicker
frequencies are typically found in modern Pulse-Width Modulated (PWM) LED
lighting systems now available and becoming increasingly popular in virtually
all lighting environments.

How the TCS3408 reduces flicker artifacts

When visible light modulations from flickering lights are
captured while a camera's rolling shutter is in operation, the resulting effect
is an image or video with distorted banding artifacts. The TCS3408 device
incorporates a flicker detection engine that detects the presence or absence of
50Hz or 60Hz flicker typically generated from incandescent or fluorescent
lights. When flicker is detected, it is captured and reported through internal
status registers of the device and the digital I2C interface enables fast
reporting of output information with external processing. Knowing that flicker
is present, the camera's video processor synchronizes the shutter with the “on”
portion of the relative ambient light output in a scene. With this additional
information from the TCS3408, the video processor can eliminate the distorting
banding artifacts and produce images that truly represent the image seen by the
user.

ams optical sensing expertise

The TCS3408 is the latest in a line of intelligent optical
sensors from ams for use in mobile phones for display color and brightness
management to enhance a cameras image enhancement. It offers ultra-high color
and 10X ALS sensitivity and half the operating power consumption versus
competition. The development of color sensors with on-chip flicker detection
capability for the detection of modern light source flicker are the key reasons
why smartphone manufacturers trust ams for delivering the industry's best
performing optical sensing solutions to help them differentiate their products.

The TCS3408 is available now in production volumes. Unit
pricing is $1.25 in an order quantity of 1,000 units.