DxOMark Mobile report: Samsung Galaxy S6 / S6 Edge

DxOMark Mobile Report: Samsung Galaxy S6 / S6 Edge

Summary

The Galaxy S6 and Galaxy S6 Edge are Samsung's latest flagship smartphones and were launched at the Mobile World Congress in March. Apart from the curved screen edges of the S6 Edge they come with identical specifications and use the same camera hardware and software. A 16MP BSI CMOS sensor is combined with a very fast F1.9 lens and an optical image stabilization system. The camera features subject tracking and is always in stand-by mode which means it can be launched in under one second by double-tapping the home button. DxOMark used an S6 Edge for its testing but due to the identical camera specifications results are valid for both the S6 and S6 models.
With a DxOMark Mobile score of 86 the Samsung Galaxy S6 Edge is the new number one in the DxOMark smartphone rankings, relegating its stablemate Galaxy Note 4 to the number two spot. The DxOMark team reports the Galaxy S6 Edge images show "very fine detail and low noise levels in bright light conditions" and "good color and white balance in all outdoor conditions". Exposure is good and the autofocus performs swiftly. The images also show "good detail preservation in low light" and when using the flash with no other light source. On the downside, "slight noise is noticeable in low light conditions", images show "slight color fringing" and when "using the flash mixed with tungsten illuminant white balance turns slightly yellow/green".
When shooting in the Samsung Galaxy S6 Edge's video mode footage shows "fine detail with low noise in bright and low light conditions, good exposure, white balance and color rendering". However, "a strong jello effect is noticeable". There is also a "slight flare in sunny scenes" and "slight color shading under indoor conditions".

Still Photography

Color, Exposure and Contrast

The DxOMark team found that on the Samsung Galaxy S6 exposure was good and that "outdoors white balance and colors are nice in all conditions". However, "in low tungsten light the white balance turns yellow" and "very slight color shading is visible in low light conditions".

Overall DxOMark awarded the Samsung Galaxy S6 scores of:

• 4.6 out of 5 for Exposure
• 4.6 out of 5 for White Balance accuracy
• 4.3 out of 5 for Color shading in low light*
• 4.4 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 on the Samsung Galaxy S6 outdoor images show "very fine detail and low noise levels" and that "detail is still visible in low light". On the downside "slight noise is noticeable in low light  although noise reduction is efficient".

Texture Acutance

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.

	A dead leaf pattern is designed to measure texture acutance. It's obtained by drawing random shapes that occlude each other in the plane, like dead leaves falling from a tree. The statistics of this model follow the distribution statistics in natural images.
	In this example from a DSLR without edge enhancement, sharpness seems equal on edge and on texture. Many details are visible in the texture.
	In this second example, edges have been digitally enhanced, and the edge looks over sharp, with visible processing halos ("ringing"). On the texture part, many details have disappeared.

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.

Note: Acutance is a single value metric calculated from a MTF result. Acutance is used to assess the sharpness of an image as viewed by the human visual system, and is dependent on the viewing conditions (size of image, size of screen or print, viewing distance). Only the values of texture acutance are given here. The measurements are expressed as a percentage of the theoretical maximum for the chosen viewing condition. The higher the score, the more details can be seen in an image. 

 

For all DxOMark Mobile data presented on connect.dpreview.com we're only showing 8MP equivalent values, which gives us a level playing field for comparison between smartphone cameras with different megapixel values by normalizing all to 8MP (suitable for fairly large prints). DxOMark also offers this data for lower resolution use-cases (web and onscreen). For more information on DxOMark's testing methodology and acutance measurements please visit the website at www.dxomark.com.

Luminance texture acutance is slightly higher under daylight than under tungsten illumination.

In terms of texture acutance, the Galaxy S6 leads the pack at all light levels.

Edge Acutance

Edge acutance is a measure of edge sharpness in images captured by the phone's camera. Again we're only looking at the most demanding of the three viewing conditions that DxOMark reports on - the 8MP equivalent.

Edge acutance on the Galaxy S6 is high but the Galaxy Note 4 beats is sister model S6 across the illumination range. In bright light the Google Nexus 6 is better as well.

Edge acutance is high across all light levels.

Visual Noise

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 levels under tungsten illumination are low across all light levels.

Under daylight noise levels are slightly lower than under tungsten illumination.

The Galaxy S6 has lower noise levels than the iPhone 6 Plus, Note 4 and Nexus 6.

Noise and Detail Perceptual scoring

DxOMark engineers don't just point camera phones at charts, they also take and analyze scores of real-world shots and score them accordingly. Their findings for the Samsung Galaxy S6 were:

Natural scene

• Texture (bright light): 4.8 out of 5
• Texture (low light): 3.6 out of 5
• Noise (bright light): 4.1 out of 5
• Noise (low light) 3.7 out of 5

Bright light sample shot.	Low light (20 Lux) studio shot
100% crop: fine detail and low noise	100% crop: some luminance noise in areas of plain color

100% crop: still good detail in this low-light shot

Artifacts

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 S6 are shown below:

• Slight sharpness drop-off toward the corners
• Slight color fringing

Perceptual Scores

• Sharpness 3.8 out of 5
• Color fringing 3.5 out of 5

Measured findings

• Ringing center 11.8%
• Ringing corner 7.3%
• Max geometric distortion -0.4%
• Luminance shading 10.5%

Distortion and Chromatic Aberrations

The graph shows the magnification from center to edge (with the center normalized to 1). Like many smartphones the Samsung Galaxy S6 shows a slight pincushion distortion, which you are not going to notice in normal photography.

Some lateral chromatic aberration is measurable but won't usually be a problem in normal photography.

Autofocus

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 S6 performs very well. The overall score is 96/100 in bright light and 92/100 in low light.

Pros: 

• Fast and precise autofocus

Cons: 

• Focus slows down with some overshooting in low light.

Autofocus repeatability - average acutance difference with best focus: low light 2.96%, bright light 2.70%

Flash

DxOMark scored the Samsung Galaxy S6 87/100 overall for its flash performance which one point higher than the Galaxy Note 4 and three points higher then the iPhone 6 Plus.

Pros: 

• Good detail, low noise levels, accurate white balance and color without any additional light sources

Cons:

• Under a tungsten illuminant (20 lux), flash white balance turns yellow/green.
  

Overall DxOMark Mobile Score for Photo: 88 / 100

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Video Capture

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 S6's video performance to be excellent, with good detail and exposure. However, the stabilization system can create noticeable distortion.   

Pros: 

• Good texture and low noise in all light conditions
• Videos are well exposed
• Good white balance and color rendering

Cons: 

• Stabilization creates strong distortion
• Slight flare when recording sunny scenes
• Slight color shading

Overall DxOMark Mobile Score for Video: 84 / 100

DXOMark Mobile Score

86

DXOMark Image Quality Assessment

The Galaxy S6 and Galaxy S6 Edge are Samsung's latest flagship smartphones and jointly succeed last year's Galaxy S5. With a 16MP BSI CMOS sensor, F1.9 aperture and optical image stabilization the new models share an improved imaging specification that translates into real-world results.
In the DxOMark testing the Galaxy S6 Edge performed very well and with a score of 86 points is the new number one in the DxOMark smartphone rankings, relegating its stablemate Galaxy Note 4 and the iPhone 6 Plus to the number two and three spots respectively. The Galaxy S6 Edge captures good detail in all light conditions, color and white balance are reliable and the AF works swiftly. Some noise is visible in low light and when using the flash you can end up with a color cast under tungsten light, but those issues are shared with many other smartphones.
The Galaxy S6 Edge performs equally well in video mode. Detail, exposure and white balance are good. On the downside "rolling shutter" effect is noticeable and under artificial light color casts can occur. For a more detailed analysis, visit www.dxomark.com.

Photo Mobile Score	88		Video Mobile Score	84
Exposure and Contrast	90		Exposure and Contrast	89
Color	85		Color	84
Autofocus	94		Autofocus	90
Texture	90		Texture	89
Noise	84		Noise	96
Photo Artifacts	79		Video Artifacts	89
Flash	87		Stabilization	59