Category Archives: Scientific Publications

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 […]

Camera quality is a major reason for consumers to choose between smartphones. However, evaluating a camera’s quality is costly, cumbersome, and, in many cases, a non-repeatable process. To simplify and improve this process, many techniques have been developed for automatic image quality assessment. In the state of the art, image detail quality assessment is predominantly […]

Color appearance across ambient Correlated Color Temperature (CCT) changes is an important aspect for preferred image quality. Smartphones nowadays are equipped with ambient illumination sensors, called Ambient Light Sensors (ALS), that are capable of detecting the illuminance information in terms of illuminance and CCT (either spectral or color). These sensors aid the detection of ambient […]

Several studies in the past have proposed models to characterize the colorimetry of displays, most of which have poor performance for OLED displays. This is primarily due to the dependency of the colorimetry of OLED panels on the AveragePixel Level (APL) of the content displayed on them. In this study, a workflow is proposed to […]

Smartphones are exposed to a variety of illumination changes. For the best user experience, it is important that their rendering is consistent across illuminance changes. In this study the rendering consistency performance of three differentsmartphones is studied across three illuminance conditions (0,320 and 9000 lux) using a haploscopic setup. It was found that the Samsung […]

HDR videos can be encoded in a variety of formats with dynamic metadata, the most popular of which are Dolby Vision, HDR Vivid and HDR10+. In this paper, the decoding strategies of these three encoding options are subjectively analyzed in order of their preference in smartphones by performing a psychophysical experiment in a laboratory environment. […]