DxOMark Mobile Report: Sony Xperia M5
In terms of processing power, look and feel the Sony Xperia M5 is categorized below Sony's Xperia Z flagship line of smartphones. However, like the Z-models it's dust-proof and waterproof and has a lot to offer in the photography department. In the rear camera a 21.5MP Sony Exmor sensor with on-chip phase detection is combined with an F2.2. aperture, and is capable of 4K video recording. Frequent self-portrait shooters will appreciate the 13MP front camera.
With a DxOMark Mobile score of 79 the Sony Xperia Z5 currently ranks as the best mid-range device in the DxOMark smartphone rankings and performs on the same level as previous generation flagship phones like the Sony Xperia Z3 or the Samsung Galaxy S5. When shooting still images with the Xperia M5 the DxO testers liked its 'good detail preservation, good noise levels and a fast and generally accurate autofocus'. However, they also found 'loss of sharpness in the corners, occasional white balance casts and visible exposure and color irregularities when shooting outdoors'. In flash mode they criticized 'strong chroma noise, especially near the corners'.
In video mode the team notes 'fast autofocus, good colors and white balance in bright light and fast exposure and white balance transition'. On the downside, they noted a 'strong jello effect and loss of detail, slightly desaturated colors and visible noise in low light'. They also found the AF to acquire focus abruptly and not have any tracking capabilities.
Color, Exposure and Contrast
The DxOMark team found that the Sony Xperia M5 images showed 'generally good exposure' but also identified a range of problems: the white balance sometimes fails under daylight and colors can be desaturated. Under tungsten light a yellow cast is visible and exposure and color irregularities are visible when shooting outdoors. The testers also found blown highlights in bright scenes.
Overall DxOMark awarded the Sony Xperia M5 scores of:
- 4.4 out of 5 for Exposure
- 4.0 out of 5 for White Balance accuracy
- 4.1 out of 5 for Color shading in low light*
- 4.2 out of 5 for Color shading in bright light*
- 3.0 out of 5 for Color Rendering in low light
- 4.3 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 Sony Xperia M5 images show 'good detail preservation and noise levels in all conditions'. On the downside, 'exposure time is slightly too long 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): 4.7 out of 5
- Texture (low light): 3.7 out of 5
- Noise (bright light): 4.0 out of 5
- Noise (low light) 3.8 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 Sony Xperia M5 are shown below:
- Loss of sharpness in the corners
- Strong ringing
- Halo and ghosting
- Blocking artifacts are occasionally visible
- Slight fringing
- Sharpness 4.2 out of 5
- Color fringing 3.5 out of 5
- Ringing center 18.8%
- Ringing corner 4.5%
- Max geometric distortion -0.2%
- Luminance shading 7.2%
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 Sony Xperia M5 performs well in all light conditions. The overall score is 80/100 in bright light and 80/100 in low light.
- Fast and generally accurate autofocus
- Some irregularities in bright light
- Some oscillations in preview mode in low light
The Sony Xperia M5 offers a LED flash for illumination in very low light. DxOMark scored the camera 80/100 overall for its flash performance.
- Good detail preservation
- Strong chroma noise, especially near the corners
- Some corner shading
- Occasional white balance irregularities
Overall DxOMark Mobile Score for Photo: 81 / 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 Sony Xperia M5 video mode to offer a fast AF and good color but footage can show a strong jello effect and detail is noticeably lost in low light.
- Fast autofocus
- Good color and white balance in bright light
- Fast exposure and white balance transition
- Strong jello effect with hand-held and walking motion
- Loss of detail in low light
- Abrupt AF convergence and no AF tracking capabilities
- Noise visible in low light
- Slightly desaturated color in low light
Overall DxOMark Mobile Score for Video: 75 / 100
DXOMark Image Quality Assessment
With a DxOMark Mobile score of 79 the Sony Xperia M5 is taking a joint 16th spot in the DxOMark smartphone rankings, making it the currently best placed mid-range device. When shooting still images with the Xperia M5 the DxO testers liked the good detail, low noise levels and fast autofocus. However, they weren't too keen on the corner softness, color casts and other white balance and exposure irregularities.
The Xperia M5 videos show good color and white balance performance in bright light and both exposure and white balance adapt quickly to scene changes. However, a strong jello effect is visible during hand-held shooting and footage can be desaturated in low light. For a more detailed analysis, visit www.dxomark.com.
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