DxOMark Mobile Report

With a DxOMark Mobile score of 83 the LG G4 takes the second spot in the DxOMark smartphone rankings, between the Samsung Galaxy S6 and the Note 4. The DxOMark team reports that the LG G4 shows "very accurate and repeatable autofocus, good detail preservation in all conditions and good noise reduction in low light". "Pictures are generally well exposed with pleasant colors" and flash images show good detail preservation and color rendering as well.

On the downside, outdoor images show a range of artifacts, including "blue sky saturation, moiré and fringing". "In very bright conditions some high-contrast scenes tend to be over-exposed" and "occasionally, white balance fails severely in outdoor pictures". Additionally "some luminance noise is visible in outdoor images, the autofocus lacks smoothness in preview" and when shooting with flash "chroma noise is visible, especially in the corners".

Video footage "generally shows good exposure and color rendering, detail preservation and noise reduction, especially in bright light". However, "stabilization is ineffective, with a visible jello effect", there is "visible color shading, especially in low light, in low tungsten light white balance turns slightly pink and in very bright light conditions, highlights are occasionally blown out".

Still Photography

Color, Exposure and Contrast

The DxOMark team found that when shooting with the LG G4 "pictures are generally well exposed" and "in outdoor pictures colors are pleasant in most situations". However, "in very bright light conditions, some high-contrast scenes can be over-exposed", occasionally auto white balance fails and the DxO engineers report that images show a "slightly pinkish cast in low tungsten light".

Overall DxOMark awarded the LG G4 scores of:

  • 4.5 out of 5 for Exposure
  • 4.4 out of 5 for White Balance accuracy
  • 3.5 out of 5 for Color shading in low light*
  • 4.4 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 G4 images show "good detail preservation in all conditions and good noise reduction in low light". However, "some luminance noise is visible in outdoor conditions".

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 is good across all light levels.
In terms of texture acutance, the LG G4 is battling the Samsung Galaxy S6 for the top spot in out comparison. 

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 LG G4 is competing with the best in its class. 
Good edge acutance is maintained 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 low across light levels. 
In this comparison only the Moto X Style's noise levels are lower in low light than the G4. However, the LG produces the highest noise levels 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 G4 were:

Natural scene

  • Texture (bright light): 4.7 out of 5
  • Texture (low light): 3.7 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: good detail preservation in outdoor conditions 
100% crop: some luminance noise is visible
Low light (20 Lux) studio shot
100% crop: good detail preservation
100% crop: low noise levels

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 G4 are shown below:

  • Blue sky saturation in bright outdoor scenes
  • Moiré visible on high frequency patterns
  • Slight color fringing noticeable in backlit scenes
  • Slight ringing noticeable in outdoor shots
  • Occasional ghosting visible in low light
Occasional ghosting is visible in low light.

Perceptual Scores

  • Sharpness 3.9 out of 5
  • Color fringing 2.9 out of 5

Measured findings

  • Ringing center 11.1%
  • Ringing corner 3.6%
  • Max geometric distortion -0.3%
  • Luminance shading 13.8%

Distortion and Chromatic Aberrations

The graph shows the magnification from center to edge (with the center normalized to 1). The LG G4 shows a slight complex distortion, which you are not going to notice in normal photography.
Some lateral chromatic aberration is measurable and slightly noticeable on some high-contrast edges.

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 LG G4 performs very well in all light conditions. The overall score is 96/100 in bright light and 93/100 in low light.

Pros: 

  • Very accurate and repeatable autofocus
  • Fast autofocus in bright light

Cons: 

  • Lack of smoothness in preview
  • Occasional instabilities in preview
Autofocus repeatability - average acutance difference with best focus: low light 0.56%, bright light 0.70%

Flash

The LG G4 comes with a dual-LED flash and DxOMark scored the camera 81/100 overall for its flash performance. 

Pros: 

  • Good detail preservation
  • Good color rendering

Cons:

  • Chroma noise visible, especially in the corners
  • White balance turns slightly green when flash is mixed with tungsten illuminant
  • Visible lens shading

Overall DxOMark Mobile Score for Photo: 86 / 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 LG G4's video footage to show good exposure and color and good detail in bright light. However, video stabilization is ineffective, often resulting in a jello effect and in low light color shading is noticeable. 

Pros: 

  • Generally good exposure and color rendering
  • Good detail preservation and noise reduction, especially in bright light

Cons: 

  • Ineffective stabilization with visible jello effect
  • Visible color shading, especially in low light
  • In low tungsten light the white balance turns slightly pink
  • In very bright light conditions highlights are occasionally blown out

Overall DxOMark Mobile Score for Video: 79 / 100