DxOMark Mobile Report: HTC One A9
In the HTC device lineup the One A9 sits just below the flagship One M9. However, in the camera department, with its faster F2.0 aperture and optical image stabilization, it actually offers some advantages over the M9. On the downside it has to make do with a lower 13MP pixel count and Full-HD video instead of the M9's 21MP still images and 4K video footage. There is also a dual-LED flash and the A9 is, like the M9, capable of recording DNG Raw files.
With a DxOMark Mobile score of 78 the HTC A9 achieves a 9 point better result than the M9 but cannot place itself among the currently best smartphone cameras. It performs on a similar level as previous generation devices such as the Google Nexus 6 or Sony Xperia Z2 and slots in at a joint number 19 in the DxOMark smartphone rankings. During testing the DxOMark team liked the "fast and accurate autofocus in bright light conditions" but also found a number of problems: "in high-contrast scenes images are often under-exposed and lack dynamic range, when shooting in daylight and low tungsten light images often show a pink color cast" and the "shutter speed in low light is too low (1/8 s at 20 Lux), resulting in blurred images." The testers also found "autofocus instabilities in preview in all conditions" and over-exposed images and AF-irregularities when shooting with flash.
In video mode the DxO team liked the "good color rendering and white balance transition" and "low noise levels". On the downside, "fine detail is lost in all conditions, autofocus overshoots are strongly visible, mainly from macro to infinity, and there is an unpleasant jello effect". The testers also found a "lack of detail in the shadow areas" when recording video in low light and the stabilization to be inefficient, particularly for roll correction.
Color, Exposure and Contrast
The DxOMark team found that when shooting with the HTC One A9 "colors are pleasant in all conditions" but "in high-contrast-scenes images are often under-exposed and lack dynamic range" and "white balance often has a pink cast when shooting in daylight or low tungsten light". The testers also found "slight color shading in low light and bright light conditions" and that the "white balance is sometimes inconsistent across consecutive shots".
Overall DxOMark awarded the HTC One A9 scores of:
- 4.2 out of 5 for Exposure
- 3.5 out of 5 for White Balance accuracy
- 4.1 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 HTC One A9 images show "good edge preservation" but also that "fine detail is lost in bright light and low light conditions, image blur is caused by slow shutter speeds in low light and luminance noise is visible 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): 3.3 out of 5
- Noise (bright light): 3.9 out of 5
- Noise (low light) 3.2 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 HTC One A9 are shown below:
- Visible ringing
- Noticeable color fringing
- Blue sky saturation can sometimes be observed
- Sharpness 4.4 out of 5
- Color fringing 3.8 out of 5
- Ringing center 17.7%
- Ringing corner 7.6%
- Max geometric distortion -0.2%
- Luminance shading 19.0%
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 HTC One A9 puts in a decent but not outstanding performance. The overall score is 87/100 in bright light and 82/100 in low light.
- Fast and accurate autofocus in bright light
- Accurate autofocus in low light
- Instabilities in preview in all conditions
- Oscillations are sometimes visible in preview in low light
The HTC One A9 comes with a dual-LED flash and DxOMark scored the camera 81/100 overall for its flash performance.
- Good flash uniformity
- Good flash white balance
- Slight over-exposure in flash images
- Autofocus irregularities are noticeable
- Fine detail is lost
- Very slow shutter speeds in flash mode
Overall DxOMark Mobile Score for Photo: 80 / 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 HTC One A9's video footage to show good color and low noise levels. However, there is little detail in the footage, the stabilization system is not efficient and an unpleasant jello effect becomes visible when panning.
- Good color rendering and white balance transition
- Low noise levels
- Autofocus overshoots are very noticeable, mainly from macro to infinity
- Fine detail is lost in all light conditions
- Footage shows unpleasant jello effect
- Little shadow detail in low light footage
- Inefficient stabilization, particularly for roll correction
Overall DxOMark Mobile Score for Video: 74 / 100
DXOMark Image Quality Assessment
With a DxOMark Mobile score of 78 the HTC One A9 takes a joint number 19 spot in the DxOMark smartphone rankings, performing on a similar level as previous generation smartphone cameras such as the Sony Xperia Z2 or Google Nexus 6.
The DxOMark team liked the A9's fast and accurate autofocus in bright light but also noted a few problems, including underexposure in high-contrast scenes, color casts and very slow shutter speeds in low light resulting in image blur. In video mode the DxO team liked the colors and low noise levels but observed autofocus-irregularities, a strong jello-effect and inefficient image stabilization. For a more detailed analysis, visit www.dxomark.com.
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