Insights: DxO Labs' scientists share their expertise
A selection of papers written by the imaging experts at DxO Labs, explaining image quality measurement technologies, case studies, and hot topics relevant to DxOMark content.
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Since the launch of the DxOMark website, many debates have arisen about ISO sensitivity: Some manufacturers were accused of cheating, the ISO sensitivity measured by DxOMark was claimed to be meaningless for photographers. The DxOMark team would like to clarify certain points. |
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For years, lens makers have fought hard to market lenses of wider and wider aperture. Wide apertures (e.g., f /1.4 instead of f /2) but a series of measurement published on dxomark.com cast some doubts on the real benefits, for digitally equipped photographers, of these progresses. |
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The Nikon D5000 and the Canon EOS 500D were two main releases for spring 2009. Launched at the same time, and targeting the same market, these two cameras were the perfect subjects to use for an extensive demonstration of the DxOMark Database. |
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Shooting pictures in RAW gives DSLR users the opportunity to fine-tune their settings, by potentially controlling every step of the RAW conversion. Users often assume that RAW images are directly output from the sensor without any additional processing, but is this really the case? What kind of processing can be applied and what kind of influence does it have on the final image? |
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DSLR sensor technology has made significant advances over the past several years, with full-frame sensors outpacing the progress of APS-C sensors. DxO Labs measurements show that advances in pixel and RAW conversion technologies have compensated for the decrease in signal-to-noise ratio (SNR) brought about by the proliferation of smaller, less light-sensitive pixels in DSLRs. Overall, today’s high-resolution cameras produce higher-quality images than low-resolution cameras when viewed or printed under the same conditions. |
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This Insight uses specific DSLRs to demonstrate the technique for objectively comparing noise for cameras with different levels of resolution. Such comparisons conclusively show better results overall for high-resolution sensors, despite the increase in noise. |
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On DxOMark, we evaluate and rank many types of digital cameras with image sensors that vary widely in pixel count, pixel size, and digital signal processing. To ensure that sensor performance comparisons between cameras are fair, it is very important both to test under identical shooting conditions and to take viewing conditions into account. |
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Noise is an integral attribute of camera sensor performance and understanding it has been essential to establish a reliable and objective DxOMark Sensor Score. This section discusses the nature of the three principal kinds of noise: photonic, thermal or electronic, and pixel response non-uniformity (PRNU), and explains how shape of Signal-to-Noise Ratio (SNR) curves relates to three metrics of DxOMark—dynamic range (low illumination), SNR (mid-tones), and color sensitivity (highlights). |
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Professional portrait and landscape photographers often use medium-format cameras because of their superb performance under controlled lighting conditions. However, as these cameras are definitely not designed for so-called “action photography” scenarios, they generally do not perform well with respect to DxO Labs’ Low-Light ISO metric. Because of this inherent low-light limitation, medium-format cameras do not receive top marks on the DxOMark Sensor Overall Score, even though they may show outstanding performance with respect to Color Depth or Dynamic Range. |
