Author Archives: DXOMARK

In this paper, we numerically quantify the information capacity of a sensor, by examining the different factors than can limit this capacity, namely sensor spectral response, noise, and sensor blur (due to fill factor, cross talk and diffraction, for given aperture). In particular, we compare the effectiveness of raw color space for different kinds of […]

This article explains the cause of the color fringing phenomenon that can be noticed in photographs, particularly on the edges of backlit objects. The nature of color fringing is optical, and particularly related to the difference of blur spots at different wavelengths. Therefore color fringing can be observed both in digital and silver halide photography. 

A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller […]

This article proposes new measurements for evaluating the image quality of a camera, particularly on the reproduction of colors. The concept of gamut is usually a topic of interest, but it is much more adapted to output devices than to capture devices (sensors). Moreover, it does not take other important characteristics of the camera into […]

A unique digital postprocessing technique compensates for performance problems posed by ever-shrinking pixels | by Dr. Guichard Frédéric, DXOMARK | From Photonics Spectra , November 2007. As camera phones become ubiquitous, consumer demand for a photographic experience similar to that of traditional digital cameras is growing. 

We define color sensitivity or effective color depth based on the “number of reliably distinguished colors”, using ideas from information theory. This figure of merit allows the comparison of different sensors or cameras and we indicate how it can be used both for the design of imaging devices and to optimize their adaptation to the […]

Noise is an important factor in image quality. We analyze it in images produced by digital cameras. We show that, beyond the usual standard deviation measurement, spatial correlations also convey interesting information which allows to (i) better describe the perception of the noise, (ii) analyze an unknown imaging chain. Indeed, knowledge of these spatial correlations […]

After discussing usual approaches to measuring blur of optical chains, we show theoretically that there is essentially a unique way to quantify blur by a single number. It is the second derivative at the origin of the Fourier transform of the kernel. This somewhat surprisingly implies that blur is especially sensitive to attenuation of the […]

In the ever-evolving field of photography, portraits have become a prominent focus of interest, especially with the rise of smartphone photography. Traditionally, objective evaluation of detail preservation has mainly centered on non-statistical methods. These methods often use synthetic content, such as edges or patterns that can simulate, in some cases, properties of natural images, as […]

The Human Visual System (HVS) can adapt to very extreme light conditions that can expand a dynamic range of 120 dB with adaptation, and up to 40 dB without adaptation [17]. However, most cameras find it challenging to reproduce fine details under High Dynamic Range (HDR) scenes (with dynamic range up to 80 dB). The […]

Portrait Quality Assessment (PQA) is becoming increasingly important in a variety of fields, from social media engagement to professional photography. The subjective nature of aesthetic appreciation, combined with the technical complexities of image capture and processing, makes PQA a challenging task. While Redi et al. have explored the attributes that contribute to the perceived beauty […]

Smartphones have significantly altered the landscape of photographic practices, with a notable emphasis on portrait photography. As the consumer base becomes increasingly discerning, there is a clear escalation in expectations regarding the quality of portrait images. This trend pushes a corresponding advancement in camera technology driving manufacturers to focus on improving image quality, which usually […]