Noise, Resolution and Sensitivity
With a 15.8-million-pixel resolution, the G3 is capable of resolving a lot of detail. At high sensitivities this is often lost due to noise reduction and sharpening
There was some doubt as to how well four thirds sensors would fare when the resolution was increased beyond 12 million pixels. Advances in sensor design and technology mean that the increase to 16.05 million pixels in the GH2, and now the 15.8 million pixel sensor in the G3, have been possible. As the dynamic range has been improved, so too has the control of image noise, particularly at high sensitivities.
The amount of detail resolution found in JPEG images is as expected for a four thirds sensor with a resolution of almost 16 million pixels. When shooting JPEG images at the base ISO 160 sensitivity, the G3 is capable of resolving up to around 24 on our resolution chart. Impressively, it is still almost at this level at ISO 6400, albeit with more than a hint of image processing.
When shooting real scenes, the JPEG images taken with the G3 have a familiar four thirds sensor quality to them. Colour noise in the form of a purple and green tinge can be seen in shadow areas, even at ISO 200, as can a slight speckling of luminance noise. Noise reduction is clearly used to reduce the effects of both of these, but this can leave surfaces a little lacking in texture, while edges look sharpened to compensate.
Raw files are more detailed than their JPEG equivalents, with images taken at ISO 160 just about reaching 26 on our chart. However, viewing raw images with all noise reduction turned off gives you a real insight into how effective the in-camera noise reduction is for JPEG files. Colour and luminance noise are easily visible at low sensitivities, although the Silkypix Developer Studio 3.1 software does a good job of reducing this noise.
Overall, in terms of noise and resolution, images taken with the G3 are on a par with those from the GH2, while producing images with slightly more detail than the 12.1-million-pixel G2. Importantly for Panasonic, the increase in resolution doesn’t seem to have made a difference in terms of image quality. High-sensitivity images from the G3 have slightly less noise than their G2 equivalents. However, I found that the default noise reduction and sharpening settings could be turned down and up a step, respectively, to improve details in JPEG files.
I wonder how the technology found in the new 15.8-million-pixel sensor would make a difference if it were used in a 12.1-million-pixel sensor. Presumably, there would have been even greater improvements in image quality, with a slight trade off in detail resolution.
Resolution charts:
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using the 14-42mm f/3.5-5.6 kit lens.
We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately.
The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting.
