DxOMark sensor scores
To help photographers rank and compare photographic equipment, DxOMark provides four scores showing camera sensor image quality performance:
Key points about DxOMark Sensor Scores:
- All sensor scores reflect only the RAW sensor performance of a camera body. All measurements are performed on the RAW image file BEFORE demosaicing or other processing prior to final image delivery. DxOMark does not address such other important criteria as image signal processing, mechanical robustness, ease of use, flexibility, optics quality, value for money, etc. While RAW sensor performance is critically important, it is not the only factor that should be taken into consideration when choosing a digital camera.
Sensor Overall Score
Sensor Overall Score AND resolution are two independent metrics of sensor performance. This means that just because camera A has more pixels than camera B (and thus sees more details) does not mean that camera A’s Sensor Overall Score will be better. Rather, Sensor Overall Score measures the quality of the captured signal, either at a pixel level or at the full sensor level. So before comparing cameras with Sensor Overall Score, it is important to first determine the resolution you are looking for (which largely depends on the size of the screen or the print you intend to use or produce).
Once you choose an appropriate resolution, the Sensor Overall Score becomes a fair and powerful tool with which to make comparisons.
In a camera, resolution is dependent on both sensor and lens performances. So to compare and rank digital cameras while taking resolution into account, you should look at the DxOMark Score for lenses (with camera), which weighs a number of image quality parameters, including resolution.
- Sensor Overall Score is logarithmic. A 5-point difference on the scale corresponds to a gain or loss of sensitivity of 1/3 of a stop.
- Sensor Overall Score is normalized for a defined printing scenario—8Mpix printed on 8"x12" (20cmx30cm) at 300dpi resolution. Any other normalization, even at a higher resolution, would lead to the same ranking, given that any camera that could not deliver the chosen resolution would be eliminated from the comparison.
- Sensor Overall Score is open and it is not a percentage. This score has been computed so that the current set of cameras, from low-end DSCs up to professional DSLRs and medium-format cameras, show results within a range from 0 to 100. However, new technologies may well lead to higher performance models.
Sensor Use Case Scores
- Each sensor use case score is defined by a specific image quality metric. Therefore the reported value for each score is expressed with the unit of the corresponding metric, as follows:
- Portrait Score is defined as the color depth performance and its unit is a number of bits;
- Landscape Score is defined as the maximum dynamic range performance and its unit is an exposure value (EV);
- Sports Score is defined as the low-light sensitivity performance and its unit is an ISO sensitivity value.
To better use Sensor Scores:
- Identify your preferred use case: General purpose, Portrait, Landscape, and/or Sports.
- Choose the resolution that you need for the kind of photography you do.
- If you shoot in RAW, Sensor Scores will help you rank the best cameras according to the resolution and use case(s) that you have chosen.
Further readings for the DxOMark sensor scores
To provide photographers with a broader perspective about mobiles, lenses and cameras, here are links to articles, reviews, and analyses of photographic equipment produced by DxOMark, renown websites, magazines or blogs.
December 10, 2009
June 09, 2009