Yesterday at the Google event, the blogging world was surprised to hear that DxOMark, a trusted source for camera reviews, gave the Pixel phone camera a score of 89. Google proudly announced that the Pixel has the world’s most powerful mobile camera. But how exactly did DxOMark reach this score?
- 12.3MP with a Sony digital sensor
- f/2.0 with 1.55μm-sized pixels (bigger pixels can capture more photons)
- Autofocus: phase detection autofocus (PDAF) and laser detection autofocus (LDAF)
- 4K video capture at 30fps
- HD video capture at 240fps (8x slo-mo); full HD video at 120fps (4x slo-mo)
- CRI-90 dual-LED flash (CRI is color rendering index – a measure of its ability to accurately reproduce colors of different objects in comparison with a natural light source)
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- f/2.4 with 1.4µm-sized pixels
- Full HD video capture at 30fps
DxOMark Mobile Score
With a score of 89, the Google Pixel edges out top flagship phones such as the HTC 10, iPhone 7, and Samsung Galaxy S7 Edge. There is a little controversy surrounding the score. The iPhone 7 Plus has not received a score yet, and many think that this phone will match or beat the Pixel score.
In its review, DxOMark noted that the Pixel camera has a high level of detail in its photos, with low noise levels in every tested lighting condition. The photos have accurate exposure with good contrast and white balance and fast autofocus.
Color accuracy in photography is extremely important. You want to make sure that your camera – as well as your computer and smartphone screens – are accurately representing color. You can do this with color calibration, but you’ll also want to find out how your camera handles white balance.
DxOMark notes that the Pixel “produced some of the most natural-looking outdoor images we have ever seen in our tests.” The article also mentions outdoor photos with the Pixel have rich colors, life-like white balance, and great rendering of highlights and shadows.
Low Light & Indoor Scenes
In tests to see how the Pixel fares under low light, as well as indoor shooting, DxOMark used Tungsten lighting rated at 5 lux. Tungsten light has to do with the temperature scale of light, or more specifically, black body radiation.
Tungsten lights are also called “hot lights” because they put off more heat than most types of lighting. These lights tend to fall at the warmer end of the color temperature scale. Without proper filters, this light can make photos look redder. The photo that DxOMark took indoors looks fairly balanced when it comes to color temperature.
In low light scenes, the Pixel had great rendering even at 10 lux and below. Lux is a measure of how intense your light source is. It’s an SI unit of illuminance and luminous emittance, and one lux is equal to one lumen per square meter.
Since the Pixel has both types of autofocus – PDAF and LDAF – this lets the phone excel in low light. PDAF, or phase detection autofocus, works by using a sensor in the direct path of the light coming into the camera lens. The light bounces off of a mirror, and two tiny sensors detect the phase difference in the light’s path and finds the exact distance.
In contrast, LDAF or laser detection autofocus uses a laser to adjust the focus of the phone’s rear camera. The Pixel shoots out a tiny laser burst that travels out until it hits into whatever you’re photographing. The laser is reflected back towards the sensor, and an algorithm calculates the time it takes for the laser to leave and return.
Due to its nature, the LDAF system doesn’t always give you correct results. It doesn’t work that well over long distances or in open spaces, like shooting a landscape. This is where PDAF kicks in to make up for the laser.
Photos taken with the Pixel have less noise than other photos. Image noise is when the photo looks “fuzzy” because the camera sensor can’t pick up as many photons as it can with more light.
Photos taken with the Pixel’s LED flash were “stable from frame to frame.” Using a color checker, DxOMark was able to accurately test how the Pixel’s flash affected the color of the scene. The photos had great target exposure and flash falloff. Flash falloff means how powerful the flash is – how far it reaches before the light is too dim to light up the scene.
The Pixel’s flash is rated at CRI-90, which is a score that not many LED bulbs reach. CRI measures how accurately the flash keeps the color of your scene. It’s worth noting that this doesn’t refer to the color temperature of the LED flash itself. Rather, it’s about how the LED light source affects the colors of the object, compared to a radiating black body light source.
For example, an LED bulb with a CRI score as low as 20-25 can still produce bright white light, while a bulb rated at 90 could render red hues poorly, such as skin tones.
One of the features Google mentioned in the keynote was the Pixel’s HDR+ capabilities. It was first introduced in the Nexus 6P, and it lets the Pixel combine several RAW images to produce one enhanced JPEG image.
HDR, or high dynamic range, is an aspect of photography that can be hard to get right. Basically, shooting in HDR or applying an HDR filter balances the shadows and highlights of the photo. This lets you see the fine details of the image better, but it can also affect the color.
DxOMark compared the HDR+ capability of the Pixel and the Nexus 6P. The was achieved by taking a photo every second for more than 10 seconds, then comparing the image quality of each shot. If the image quality was significantly lowered, this meant that the phone didn’t have enough processing power to render the image.
The Nexus 6P wasn’t able to keep up with the Pixel. In the test, the Pixel was able to take as many as 9 HDR+ photos in a row before stalling and going back to a single-frame image. In another test, DxOMark took a photo every three seconds. In this way, the Pixel was able to shoot HDR+ photos “indefinitely.” After four photos, the Nexus 6P wasn’t able to provide HDR+.
The Final Score
- Exposure & Contrast: In exposure and contrast, the Pixel got a score of 90. As we noted above, it performed well in all lighting conditions.
- Color: The phone got a score of 85 in color. It has accurate white balance, although in one scene DxOMark notes that the Pixel gave the picture a slight yellow cast, but most people probably wouldn’t notice this unless they were a professional photographer.
- Autofocus: Since the Pixel has two kinds of autofocus, this received a score of 93. It’s both fast and accurate in most conditions.
- Details & Noise: In this category, the Pixel got a score of 93 for details and 84 for noise. This is mainly due to its use of HDR+. The only phone that rendered more details than the Pixel was the HTC 10.
- Artifacts: The score for this category was 84. JPEG artifacts, or moiré patterns, were visible in subjects with heavy patterns and high-contrast edges, like architecture.
- Flash: The flash score of the Pixel was 88. The high quality of the LED flash made this possible. While there was some flash falloff under certain conditions, this is pretty normal even in high-end smartphones. Mobile flash isn’t as powerful as the flash of a DSLR. The white balance of the flash was also accurate, even when warm tungsten light was added.
- Video: Finally, the Pixel’s video score came in at 88. Thanks to hybrid autofocus and image stabilization (although not OIS), the Pixel took great videos under most conditions. Some weaknesses in the video were apparent in certain conditions. Slight motion blur in low light while walking, jello effects from the rolling shutter (common for phones), noise, and color shading with low light. However, these issues didn’t seriously affect the video score of the Pixel.
The combination of all of these factors is what gave the Pixel a score of 89. So far, this is the highest score that a smartphone has ever achieved, and Google is quick to point this out. Combined with unlimited photo/video storage in Google Photos, the Pixel should be a good asset in any mobile photographers’ bag. You can read more about the Pixel’s review over at DxOMark.