DxOMark Mobile Report: LG G2

Summary

DxOMark Mobile score of 73 puts the LG G2 at position number six in the DxO smartphone rankings, the same level as the Nokia Lumia 925 and four points behind the current number one device, the Nokia 808 PureView

The DxOMark team reports that the G2 images show "very good detail preservation outdoors, with more details than most 8MP cameras, very low noise level in all conditions, good edge preservation in low light and good overall exposure." Images are still well-exposed in very low light, thanks to the LG's optical image stabilization system. The autofocus is "very fast and mostly repeatable" and the G2 shows "good behavior with the flash."

On the downside there is "visible color shading with some indoor lighting" and "in low light conditions, low-contrast detail is completely smoothed out, producing a cartoon effect." DxOMark observed "a slight white balance bias is sometimes noticeable outdoors." The DxO scientists also noticed the optical image stabilization system may produce "different motion blur effects while taking images on a tripod."

In video mode DxO found the G2's optical image stabilization "efficient for handheld motion and the video footage to display "low noise levels" and that "autofocus performance has improved compared to previous versions and AF triggers automatically upon subject distance changes." On the downside footage shows "low frequency color fringes in dark areas of high contrast scenes" and "white balance can fail, especially under tungsten illuminant" and also "texture detail in low light is low."

Still Photography

Color, Exposure and Contrast

The DxOMark team found that the LG G2's images show "good overall exposure" and that "in extreme low light conditions, exposure stays good when other cameras produce under-exposed images." The G2 produces "pleasant colors in all conditions" and "stable white balance in most situations."

On the downside there is "noticeable color shading with some light sources" and a "slight white balance bias is sometimes noticeable outdoors."

Overall DxOMark awarded the LG G2 scores of:

  • 4.2 out of 5 for Exposure
  • 4.0 out of 5 for White Balance accuracy
  • 3.0 out of 5 for Color shading in low light*
  • 3.5 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 LG G2 images show "very good detail preservation outdoors, with more details are visible than on standard 8MP cameras, very low noise levels in all conditions and good edge preservation in low light."

On the downside, "in low light conditions, low-contrast detail is completely smoothed out, producing a cartoon-like effect on faces and low frequency chroma noise is sometimes noticeable."

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 (textures such as fine foliage, hair, 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 is 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 its edges are sharp and if fine details are visible, but in-camera processing means 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 detail of  target made of a dead leaves pattern, designed to measure Texture Acutance. It is 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 of the same 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 a 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 showing only the 8MP equivalent values, which gives us a level playing field for comparison between phone cameras with different megapixel values by normalizing all to 8MP, suitable for fairly large prints. DxOMark also offer 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 very similar under daylight and tungsten illuminant and increases with higher light levels. 
In terms of texture acutance the LG G2 lags behind the best competitors in low light but catches up in bright light.  

Edge Acutance

Edge acutance is a measure of the sharpness of the edges in images captured by the phone's camera, and again we're only looking at the most demanding of the three viewing conditions that DxOMark reports on, "8MP equivalent."
The LG G2's ability to retain sharp edges in images is decent across all light levels. 
In terms of edge acutance leads the competition in low light but loses its lead in bright light. 

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 a 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 in daylight conditions are low across all light levels.
Noise levels under low tungsten light are slightly higher than in daylight conditions.
The LG G2's noise levels are slightly higher than some competitors in low light but on the same level as the rest of the pack in bright conditions. 

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 LG G2 were:

Natural scene

  • Texture (bright light): 4.8 out of 5
  • Texture (low light): 3.0 out of 5
  • Noise (bright light): 3.8 out of 5
  • Noise (low light) 3.8 out of 5
Bright light sample shot 
100% crop: "A gain in resolution is noticeable compared to 8 MP cameras."
Low light (20 Lux) studio shot
100% crop shows "edges are very sharp (5 dollar banknote), but low-contrast details is completely lost. Noise is almost not noticeable"
100% crop 20 lux: all fine texture is removed by noise reduction but noise levels are low.

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 LG G2 are shown below:

Issues 

  • OIS bug: sometimes the lens moves during image acquisition, causing blur in some image areas

Perceptual scores

  • Sharpness 3.5 out of 5
  • Color fringing 4.0 out of 5

Measured findings

  • Ringing center 4.5%
  • Ringing corner 1.2%
  • Max geometric distortion 0.5%
  • Luminance shading 23.8%

Distortion and Chromatic Aberrations

The graph shows the magnification from center to edge (with the center normalized to 1). The LG G2 shows a slight pincushion distortion, which you are not going to notice in normal photography.
The LG G2 shows some lateral chromatic abberations but you won't typically notice this in your images. 

Autofocus

DxOMark also tests autofocus accuracy and reliability by measuring how much the acutance — 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 condition the LG G2's AF does a decent job in bright light but is less reliable in low-light conditions. The overall score is 79/100 in bright light and 69/100 in low light.

Pros: 

  • Very fast and reactive autofocus in bright light conditions

Cons: 

  •  In low light conditions, AF is fast but takes long to react
  • AF mostly repeatable but slight focus errors happen occasionally
  • In low light conditions AF is less repeatable in trigger mode
Autofocus repeatability - average acutance difference with best focus: low light 5.6%, bright light 6.5%

Flash

DxOMark scored the LG G2 72/100 overall for its flash performance.

Pros: 

  • Good overall flash: good exposure, focus, detail and color preservation and very low noise levels

Cons: 

  • Strong light falloff in image corners
  • White balance bias under tungsten light

Overall DxOMark Mobile score for Photo: 77 / 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. We'll simply summarize for you: DxOMark found the LG G2's video performance to be decent, with low noise levels and the OIS doing a good job at stabilizing things. However, white balance is unreliable under tungsten light and noise reduction is blurring textures in low light. 

Pros: 

  • Efficient stabilization for handheld motion
  • Low noise level
  • Autofocus triggers automatically upon subject distance changes

Cons: 

  • Low frequency color fringes in dark areas of high contrast scenes
  • White balance errors, especially under tungsten light
  • Low texture performance in low light

Overall DxOMark Mobile score for Video: 64 / 100