Метод оценки качества оператора тональной компрессии

В статье предложен численный критерий оценки качества работы операторов тональной компрессии. Рассмотрены основные факторы, влияющие на восприятие преобразованного изображения зрителем. Выполнено сравнение визуальных оценок качества преобразования изображений наиболее распространенными операторами тональной компрессии с оценками, полученными при помощи предложенного критерия.The numerical criterion for the quality of tone mapping operator was proposed. The main factors which affected on huma perception of converted image were considered. For most common tone mapping operators visual and numerial estimates, which are calculated using proposed method, were compared

On evolution of CMOS image sensors

CMOS Image Sensors have become the principal technology in majority of digital cameras. They started replacing the film and Charge Coupled Devices in the last decade with the promise of lower cost, lower power requirement, higher integration and the potential of focal plane processing. However, the principal factor behind their success has been the ability to utilise the shrinkage in CMOS technology to make smaller pixels, and thereby have more resolution without increasing the cost. With the market of image sensors exploding courtesy their inte- gration with communication and computation devices, technology developers improved the CMOS processes to have better optical performance. Nevertheless, the promises of focal plane processing as well as on-chip integration have not been fulfilled. The market is still being pushed by the desire of having higher number of pixels and better image quality, however, differentiation is being difficult for any image sensor manufacturer. In the paper, we will explore potential disruptive growth directions for CMOS Image sensors and ways to achieve the same

Ein histogrammbasiertes Verfahren zur Erzeugung von High Dynamic Range-Bildern aus einer Belichtungsreihe

In dieser Bachelorarbeit wird ein Verfahren zur HDR-Bilderstellung vorgestellt und mit anderen Verfahren verglichen, das eine beliebige Belichtungsreihe verarbeitet und auf der Erstellung von Histogrammen der Helligkeitsverhältnisse zwischen den Aufnahmen basiert. Der Algorithmus wurde in Java als Plugin für die Bildverarbeitungssoftware ImageJ implementiert

Estudi comparatiu del comportament perceptual de diferents algorismes Tone Mapping

D'experiments diferents per avaluar "tone mapping operators" se n'ha fet de molts tipus diferents i amb molts objectius diferents. Nosaltres, en aquest treball, hem realitzat experiments psicofísics sobre 15 algorismes "tone mapping" diferents per tal d'obtenir un ranking des del punt de vista de la percepció humana. Per aconseguir aquest ranking, hem realitzat dos experiments diferents: un per estudiar la relació de tonalitats de grisos en la imatge "tone mapped" i en l'escena HDR real i un "pairwise comparison" dels 15 algorismes, observant l'escena HDR real just al costat del monitor CRT calibrat. Els resultats dels experiments han demostrat que, pel primer experiment, iCAM és el millor amb diferència, mentre que pel segon experiment, els millors han estat Kraw i KimK.There are a lot of different experiments to evaluate tone mapping operators. In this work, we performed psycophysics experiments with 15 different tone mapping algorithms to obtain a human perceptual ranking. To achieve this ranking, we performed two different experiments: one to study the relationship between gray tones, and the other performed a pairwise comparison of these 15 algorithms. In the first one, we matched the gray tones in the tone mapped image and in the HDR real scene. In the second one, we performed a pairwise comparison of tone mapped images, while watching the HDR real scene next to the CRT calibrated display. We built a ranking from the pairwise comparison results using the Balanced Rank Estimation method implemented by Wauthier et al.(2013). The results of the experiments showed that iCAM is the best tone mapping operator for the first experiment, while Kraw and KimK are the best for the second one

High Dynamic Range Images Coding: Embedded and Multiple Description

The aim of this work is to highlight and discuss a new paradigm for representing high-dynamic range (HDR) images that can be used for both its coding and describing its multimedia content. In particular, the new approach defines a new representation domain that, conversely from the classical compressed one, enables to identify and exploit content metadata. Information related to content are used here to control both the encoding and the decoding process and are directly embedded in the compressed data stream. Firstly, thanks to the proposed solution, the content description can be quickly accessed without the need of fully decoding the compressed stream. This fact ensures a significant improvement in the performance of search and retrieval systems, such as for semantic browsing of image databases. Then, other potential benefits can be envisaged especially in the field of management and distribution of multimedia content, because the direct embedding of content metadata preserves the consistency between content stream and content description without the need of other external frameworks, such as MPEG-21. The paradigm proposed here may also be shifted to Multiple description coding, where different representations of the HDR image can be generated accordingly to its content. The advantages provided by the new proposed method are visible at different levels, i.e. when evaluating the redundancy reduction. Moreover, the descriptors extracted from the compressed data stream could be actively used in complex applications, such as fast retrieval of similar images from huge databases

АДАПТИВНОЕ СЖАТИЕ ШИРОКОГО ДИНАМИЧЕСКОГО ДИАПАЗОНА ЦИФРОВЫХ РАДАРНЫХ СПУТНИКОВЫХ ИЗОБРАЖЕНИЙ

Transformation of a digital radar image with a wide dynamic range of luminance values (up to 216 tones) for visualization on a standard monitor is considered. The monitor has 28 gray value range or any of three basic colors in the RGB system. Linear quantization of the luminance values of the original image generates a nearly black image with small light blobs, since most of the original values are less than 255–512 and are reduced by 256 times. To solve the problem, it is proposed to use a nonlinear logarithmic transformation with a parameter calculated from the original images. On real data received from the TerraSAR-X satellite in the geoTIFF format, comparative studies with other compression algorithms for a wide dynamic range of image brightness are performed. It is shown that the proposed solution allows creating a visually better image in comparison with the known algorithms. Рассматривается задача преобразования цифрового радарного изображения, имеющего широкий динамический диапазон значений яркости (до 216 величин), для отображения на стандартном мониторе. Монитор имеет 28 оттенков яркости серого или каждого из трех базовых цветов в системе RGB. Линейное переквантование значений яркости исходного изображения порождает практически черное изображение с небольшими светлыми точками, так как большинство исходных значений имеют величину менее 255–512 и уменьшаются в 256 раз. Для решения поставленной задачи предлагается использовать нелинейное преобразование логарифмического типа с вычисляемым по исходным изображениям параметром. На реальных данных, полученных со спутника TerraSAR-X в формате geoTIFF, выполнены сравнительные исследования с другими алгоритмами сжатия широкого динамического диапазона яркостей изображений. Показывается, что предлагаемое решение позволяет создать визуально более качественное изображение по сравнению с известными алгоритмами