DxOMark Mobile Report: HTC One M9

Summary

The One M9 is HTC's latest top-end smartphone. The new model is a touch smaller and thinner than its predecessor, the One M8, but otherwise sports a very similar design. Under the hood HTC has finally dropped the 4MP "ultrapixel" sensor of the predecessors that produced only mediocre image quality results in our testing. Instead, the One M9 comes with a 20MP BSI CMOS sensor that is combined with an F2.2 lens. There is no optical image stabilization but the M9 is the first One model capable of recording 4K video.

With a DxOMark Mobile score of 69 the HTC One M9 improves over its predecessor by only one point and slots into the DxOMark smartphone rankings at a slightly disappointing position number 22. The DxOMark team reports that in bright light "colors and nice and pleasant, detail is good and the autofocus performs well". However, they also found the colors to be over-saturated in low light, "white balance is often inaccurate in both bright and low light" and there is a "loss of sharpness in the corners of the image". The testers also criticized "strong quantification and color gradations" in areas of plain color and "strong ringing".

When shooting in video mode the HTC One M9's autofocus is accurate and video footage shows "good noise reduction in bright light". On the downside "a lot of detail is lost in both bright and low light" and there is no video stabilization. The testers also found "visible luminance steps during exposure changes" and over-saturated colors in low light".

Still Photography

Color, Exposure and Contrast

The DxOMark team found that on the HTC One M9 "exposure behavior was overall good" and that the camera rendered "nice and pleasant colors in bright light". However, "white balance is often very green in bright light", there is "visible color shading in bright and low light" and "colors are saturated in low light".

Overall DxOMark awarded the HTC One M9 scores of:

  • 4.3 out of 5 for Exposure
  • 3.0 out of 5 for White Balance accuracy
  • 3.5 out of 5 for Color shading in low light*
  • 2.5 out of 5 for Color shading in bright light*
  • 2.5 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 M9 images show "very nice detail preservation in bright light" but that "details is smoothed in low light condition", there is "strong luminance noise in bright light" and "low frequency chrominance noise is visible in low light".

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 decreases noticeably in low light.
In terms of texture acutance, the HTC One M9 performs well in good light but trails its rivals in lower light conditions.   

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.
In terms of edge acutance the HTC One M9 compares well to the competition at all light levels.
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 are high in bright light but kept under control by noise reduction in low light.
Under daylight strong noise reduction reduces noise levels but smears detail in low light.  
Noise levels in bright and medium light are higher than the competition but noise reduction keeps things under control in low light.

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 HTC One M9 were:

Natural scene

  • Texture (bright light): 4.8 out of 5
  • Texture (low light): 2.8 out of 5
  • Noise (bright light): 3.5 out of 5
  • Noise (low light) 3.1 out of 5
Bright light sample shot
Low light (20 Lux) studio shot
100% crop: decent detail but high noise levels
100% crop: smeared detail and chroma noise is visible.
100% crop: visible loss of fine detail in low light

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 HTC One M9 are shown below:

  • Strong ringing
  • Strong quantification in areas of plain color or color gradation.
  • Slight fringing
  • Loss of sharpness in the corners of the image
100% crop: strong quantification in areas of plain color

Perceptual Scores

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

Measured findings

  • Ringing center 20.6%
  • Ringing corner 9.1%
  • Max geometric distortion -0.1%
  • Luminance shading 0.2%

Distortion and Chromatic Aberrations

The graph shows the magnification from center to edge (with the center normalized to 1). Like many smartphones the HTC One M9 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 noticeable in images.   

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 HTC One M9 performs reliably in bright light but shows some weaknesses in low light. The overall score is 78/100 in bright light and 67/100 in low light.

Pros: 

  • Autofocus is reliable in bright light

Cons: 

  •  Autofocus slightly slows down in low light
  • Some errors in low light
  •  When refocusing from macro to infinity sometimes strong overshooting is noticeable
Autofocus repeatability - average acutance difference with best focus: low light 9.34%, bright light 7.40%

Flash

DxOMark scored the HTC One M9 a low 60/100 overall for its flash performance, making its flash mode one of the worst among the current generation of top-end smartphones. 

Pros: 

  • Good flash uniformity

Cons:

  • Details are lost
  • Colors are under-saturated
  • Color clipping is noticeable
  • Strong noise in the corners
  • Color shading when flash is mixed with a tungsten light source

Overall DxOMark Mobile Score for Photo: 73 / 100

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 HTC One M9's autofocus performance to be reliable in video mode but footage shows little detail, oversaturated colors and stepping during exposure changes.    

Pros: 

  • Good noise reduction in bright light
  • Accurate autofocus

Cons: 

  • A lot of detail is lost in both bright light and low light
  • No video stabilization
  • Visible luminance steps steps during exposure changes
  • Colors are oversaturated in low-light

Overall DxOMark Mobile Score for Video: 61 / 100

DXOMark Mobile Score
69

DXOMark Image Quality Assessment

With a DxOMark Mobile score of 69 the HTC One M9 is only a slight improvement over its predecessor M8. At position number 21 in the DxOMark smartphone rankings it trails behind its main rivals in the current crop of high-end smartphones.

In its testing the  DxOMark team found detail and color to be good in bright light but things go downhill quickly as the light gets dimmer. In low light they found the colors to be over-saturated and white balance to be unreliable. There is also some noticeable corner softness and visible compression artifacts in areas of plain color. 

The HTC One M9's video mode cannot convince either. Autofocus is accurate but footage shows little detail, there is no video stabilization and brightness "stepping" is noticeable during exposure changes. For a more detailed analysis, visit www.dxomark.com.

Photo Mobile Score 73   Video Mobile Score 61
Exposure and Contrast 81   Exposure and Contrast 75
Color 67   Color 69
Autofocus 72   Autofocus 55
Texture 74   Texture 47
Noise 76   Noise 80
Photo Artifacts 71   Video Artifacts 76
Flash 60   Stabilization 26