Noise, Resolution and Sensitivity
Image: Although JPEG images are very good, the level of detail and sharpness is noticeably better by saving and editing the raw files
As the PowerShot G12 keeps the same 10-million-pixel sensor as its predecessor, the image quality is virtually identical. Our resolution chart shows that the camera is capable of resolving to around 24 when the sensitivity is set to ISO 80 and ISO 100, which is on a par with many 12-million-pixel DSLRs. Although the detail resolution does gradually fall, even at ISO 3200 it is still able to resolve around 18 on the chart.
Image: For a 10-million-pixel camera, the PowerShot G12 captures a high level of detail
In real terms this means images are full of detail at lower sensitivities. However, there is some loss of detail as sensitivities increase due to the effects of noise and noise reduction – for instance, images have a smudged appearance, but also appear to have had edge sharpening applied. This maintains edge fidelity, but larger textured areas lose some detail.
The result of the noise reduction is that while detail is lost, chroma noise is kept to a bare minimum, with just the occasional hint of green or magenta patches in shadow areas. Luminance noise is reduced less and it takes on a speckled appearance. However, given the size of the sensor and the pixel count, it is kept to a minimum and images are still usable even at the highest sensitivities.
Resolution charts: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured at the long end of the zoom (100mm). 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.
