DxOMark Mobile Report: Samsung Galaxy S7 edge
The Samsung Galaxy S7 edge is the successor to last year's Galaxy S6 edge and shares its camera specification with the slightly smaller Galaxy S7. In the camera department pixel count has been reduced from 16 to 12MP compared to the S6 edge. This results in larger 1.4um pixels or a 56 percent increase in pixel size in relation to the predecessor. Samsung has also introduced a Dual-Pixel AF-system which splits every single pixel on the sensor into two photodiodes for on-chip phase detection. Light is captured through an F1.7 aperture and an optical image stabilization system keeps things steady at slow shutter speeds and when shooting video.
In the DxOMark test the new camera specification performs very well and with a DxOMark Mobile score of 88 the Samsung Galaxy S7 edge is the new leader in the DxOMark smartphone rankings, relegating the Galaxy S6 edge plus and the Sony Xperia Z5 to a joint number 2 spot. In still image mode the testers liked "Good detail preservation in low light and fine detail in outdoor conditions, good exposure and dynamic range in all light conditions, low noise levels" and a "fast and accurate autofocus". When shooting with flash the DxOMark team found the images to show "very good detail preservation and accurate white balance and color preservation". On the downside, "under tungsten light, a yellow cast is visible, in very high-contrast scenes some image areas are clipped and ringing is visible".
When shooting video the test engineers were impressed by the "very good autofocus behavior, with good tracking capabilities and, fast and smooth convergence in all conditions". They also noted the "very good stabilization, good detail preservation in bright light, good overall exposure and color rendering and low noise levels, even in low light". Negative points included a "jitter artifact and loss of detail in low light". Slight color casts were also noticeable, particularly in low light.
Color, Exposure and Contrast
The DxOMark team found the Galaxy S7 edge images to show "good exposure and dynamic range and vivid and pleasant color in all conditions". White balance is accurate at all times as well. On the downside, "a yellow cast is visible under tungsten illuminants and color shading is slightly visible". In high-contrast scenes some highlight-clipping can occur. Overall the testers found the colors to be more saturated than on previous Samsung devices.
Overall DxOMark awarded the Samsung Galaxy S7 edge scores of:
- 4.6 out of 5 for Exposure
- 4.5 out of 5 for White Balance accuracy
- 4.3 out of 5 for Color shading in low light*
- 4.5 out of 5 for Color shading in bright light*
- 3.0 out of 5 for Color Rendering in low light
- 4.5 out of 5 for Color Rendering in bright light
*Color Shading is the nasty habit cellphone cameras have of rendering different areas of the frame with different color shifts, resulting in pictures with, for example, pinkish centers and greenish corners.
Noise and Details
DxOMark's engineers reported that the Samsung Galaxy S7 edge images show "good detail preservation in low light, low noise levels in all conditions" and good fine detail preservation in bright light. However, "very fine detail is lost in all conditions".
Texture acutance is a way of measuring the ability of a camera to capture images that preserve fine details, particularly the kind of low contrast detail (such as fine foliage, hair or fur) that can be blurred away by noise reduction or obliterated by excessive sharpening.
Sharpness is an important part of the quality of an image, but while it's easy to look at an image and decide visually whether it's sharp or not, the objective measurement of sharpness is less straightforward.
An image can be defined as 'sharp' if edges are sharp and if fine details are visible. In-camera processing means that it's possible to have one of these (sharp edges) but not the other (fine details). Conventional MTF measurements tell us how sharp an edge is, but have drawbacks when it comes to measuring fine detail preservation. Image processing algorithms can detect edges and enhance their sharpness, but they can also find homogeneous areas and smooth them out to reduce noise.
Texture acutance, on the other hand, can qualify sharpness in terms of preservation of fine details, without being fooled by edge enhancement algorithms.
At first sight, the images from these two cameras may appear equally sharp. A sharpness measurement on edges will indeed confirm this impression, and will even show that the second camera is sharper. But a closer examination of low contrasted textures shows that the first camera has better preservation of fine details than the second. The purpose of the texture acutance measurement is to qualify this difference.
Visual noise is a value designed to assess the noise in an image as perceived by the human visual system, depending on the viewing condition (size of image, size of screen or print, viewing distance). The measurements have no units and can be simply viewed as the weighted average of noise standard deviation for each channel in the CIE L*a*b* color space. The lower the measurement, the less noise in the image.
Noise and Detail Perceptual scoring
- Texture (bright light): 4.7 out of 5
- Texture (low light): 3.9 out of 5
- Noise (bright light): 4.2 out of 5
- Noise (low light) 4.2 out of 5
Phone cameras, like entry-level compact cameras, tend to suffer from artifacts such as sharpening halos, color fringing, vignetting (shading) and distortion, which can have an impact on the visual appeal of the end result. DxOMark engineers measure and analyze a range of artifacts. Their findings after testing the Samsung Galaxy S7 are shown below:
- Slight aliasing and color artifact
- Ringing visible
- Sharpness 4.2 out of 5
- Color fringing 4.0 out of 5
- Ringing center 14.0%
- Ringing corner 10.5%
- Max geometric distortion -0.4%
- Luminance shading 19.9%
Distortion and Chromatic Aberrations
DxOMark also tests autofocus accuracy and reliability by measuring how much the acutance - or sharpness - varies with each shot over a series of 30 exposures (defocusing then using the autofocus for each one). As with other tests these results are dependent on the viewing conditions (a little bit out of focus matters a lot less with a small web image than a full 8MP shot viewed at 100%). Using the 8MP equivalent setting, the Samsung Galaxy S7 edge performs very well in all light conditions. The overall score is 98/100 in bright light and 90/100 in low light.
- Fast and accurate autofocus
- Some instabilties are noticeable
The Samsung Galaxy S7 edge offers a dual-LED flash for illumination in very low light. DxOMark scored the camera 86/100 overall for its flash performance.
- Very good detail preservation, accurate white balance and color preservation
- Slight exposure irregularities
Overall DxOMark Mobile Score for Photo: 88 / 100
DxOMark engineers put phone cameras through a similarly grueling set of video tests, and you can read their full findings on the DxOMark website here. Overall, DxOMark found the Samsung Galaxy S7 edge's video mode to perform very well, with a reliable autofocus, efficient stabilization and good detail. On the downside, some jittering and a loss of detail are noticeable in low light.
- Very good autofocus behavior: good tracking capabilities, fast and smooth convergence
- Very good stabilization in all light conditions
- Good detail preservation in bright light
- Good exposure and color rendering
- Low noise levels, even in low light
- Jitter artifact visible in low light conditions
- Loss of details noticeable in low light
- Color shading is slightly noticeable in all conditions but particularly in low light
Overall DxOMark Mobile Score for Video: 88 / 100
DXOMark Image Quality Assessment
With a DxOMark Mobile score of 88 the Samsung Galaxy S7 edge takes the number one spot in the DxOMark smartphone rankings. The camera captures very good detail in all light conditions, with low noise levels across the board. Dynamic range and flash performance are very good as well and the new Dual Pixel AF system is working swiftly and reliably.
In video mode the testers were impressed by good tracking and overall AF performance as well as the efficient stabilization. Detail is good in brighter light and the only minor negatives are an occasional jitter artifact and color cast in lower light. Overall the Samsung performs impressively well and is well deserving of the top spot. For a more detailed analysis, visit www.dxomark.com.
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