My iPhone has an "auto-brightness" setting (although I cannot see any effect - perhaps my case blocks the sensor). What I don't understand from the article is how the RGB information would be used. Is the point that with light source information it would be possible to selectively brighten the colors that are being washed out by the ambient light while keeping the colors that are not present in the ambient light dim? How well does this work in practice? The human eye is very good at color correcting based upon the ambient light color temperature. If incandescent light is shifting the ambient colors towards the red end of the spectrum, the blue components of an image are "auto enhanced" and need not be so bright. If the Intersil technology utilizes this effect, it might save energy.
The digital ALS has built in amplifiers, ADCs and I2C resources to interface directly to a SoC or any uC, making ALS implementation efficient, as compared to a standalone photodiode. ISL29125 do provide independent RGB information of the light source, which is used to measure correlated color temperature (CCT) along with Lux value.
This is Naresh Shetty with Intersil. I wanted to take the opportunity to answer a couple of questions that were raised in the article. Today, ALS is used for ambient light intensity – as opposed to light source information – to manage brightness. Since device displays are translucent, a user's color perception changes depending on the source rather than intensity. RGB is currently the only way to identify light source (sunlight, fluorescent, incandescent, etc.) and therefore remains the only way to effectively adapt a display based on light. With respect to OLED solutions specifically, RGB is particularly useful for improving aging OLED display characteristics on large screens. Today, it's true that RGB is not as cost-effective for smartphone screens for the purposes of monitoring/adapting to OLED ageing.
Can you in any way substantiate your first-sentence remark, "After being off the tech radar in recent years" re Intersil? It seems very unfair to them to make such a blanket statement, and then not back it up at all in the article. It's a "dig" at them without backup. (I have no vested interest or pro/con bias with respect to Intersil, I just don't like to see such broad statements made so casually.)
Of course, measurinig ambient light for the purpose of intelligently dimming and brightening the display backlight is important. Unfortunately, this article does not make clear we do this already. The measurement is typically done with a single sensor, most commonly a photodiode, that more or less mimics the spectral response of the human eye.
What these ambient light sensors (ALSs) do not do is measure red, green, and blue light independently. So the question is whether the Intersil sensor can produce sufficiently increased user satisfaction to justify its (presumably) higher cost. The answer to that question is not at all clear.
Both low-power and sensor technologies are trending heavily these days. Obviously, mobile devices are still booming for the fourth or fifth year in a row--so a confluence of interests makes sense here.
A Book For All Reasons Bernard Cole1 Comment Robert Oshana's recent book "Software Engineering for Embedded Systems (Newnes/Elsevier)," written and edited with Mark Kraeling, is a 'book for all reasons.' At almost 1,200 pages, it ...