Apple iPhone 6s Plus camera review
DxOMark Mobile Report: Apple iPhone 6s Plus
With a DxOMark Mobile score of 84 the Apple iPhone 6s Plus takes the number 3 spot in the DxOMark smartphone rankings, placing itself between the Samsung Galaxy S6 Edge and the Google Nexus 6P. The DxOMark team reports that the iPhone 6s Plus images show "very good overall exposure and good detail preservation in bright light". The testers also liked the "fast and generally accurate autofocus" and the "stable and pleasant white balance".
On the downside, "some luminance noise is visible, especially in low light" and images show "color inaccuracies and visible color shading with indoor illuminants". The testers also found "occasional blue sky saturation and other artifacts" and flash images show noticeable vignetting.
In video mode the testers liked the "accurate and smooth autofocus, the effective stabilization and the good exposure and white balance". However, they also noted the "noise in low light conditions, especially in the corners, and visible color shading".
Color, Exposure and Contrast
The DxOMark team found that when shooting with the Apple iPhone 6s Plus images showed "very good overall exposure, stable white balance with a slight yellow cast and very nice colors when shooting outdoors". However, they also found "color inaccuracies and visible color shading with indoor illuminants".
Overall DxOMark awarded the Apple iPhone 6s Plus scores of:
- 4.6 out of 5 for Exposure
- 4.6 out of 5 for White Balance accuracy
- 4.2 out of 5 for Color shading in low light*
- 4.1 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 Apple iPhone 6s Plus images show "good detail preservation in bright light and low chroma noise". On the downside, "in low light conditions fine detail is lost and some luminance noise is visible, especially in low light".
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): 4.6 out of 5
- Texture (low light): 3.7 out of 5
- Noise (bright light): 4.0 out of 5
- Noise (low light) 3.5 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 iPhone 6s Plus are shown below:
- Blue sky saturation visible on some outdoor scenes
- Slight ghosting occasionally visible in HDR mode
- Slight Moiré in some pictures
- Slight ringing visible
- Sharpness 4.2 out of 5
- Color fringing 3.2 out of 5
- Ringing center 7.8%
- Ringing corner 5.7%
- Max geometric distortion -0.3%
- Luminance shading 3.4%
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 Apple iPhone 6s Plus performs very well at all light levels. The overall score is 94/100 in bright light and 89/100 in low light.
- Fast and generally accurate autofocus in all conditions
- Stable focus in preview
- Some irregularities in low light when touch-to-focus is used
The Apple iPhone 6s Plus comes with a dual-LED flash and DxOMark scored the camera 83/100 overall for its flash performance.
- Good exposure with and without additional light sources
- Stable exposure and white balance in all conditions
- Visible noise, especially near the corners
- Visible attenuation in the corners without additional light sources
Overall DxOMark Mobile Score for Photo: 84 / 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 Apple iPhone 6s Plus video footage to be well exposed, with good stabilization and white balance. AF is smooth and accurate in all situations but noise and color shading are noticeable in low light.
- Fast, accurate and smooth autofocus
- Good overall exposure and white balance
- Effective stabilization in all conditions
- Noise noticeable in low light, especially in the corners
- Sometimes tremors are visible
- Visible color shading in all conditions
Overall DxOMark Mobile Score for Video: 82 / 100
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