Daniele D. Giusto

Detection of foreign bodies in food by thermal image processing

This paper deals with the problem of detection of foreign bodies in food. A new method for inspecting food samples is presented, using thermographic images to detect foreign bodies that are not detectable using conventional methods. At first, the basic background of thermography is given. Then, experiments to obtain well-contrasted thermographic images of different food and foreign bodies are discussed. The main part of the present paper introduces specific image processing methods that show a good recognition power of foreign bodies within food. Results achieved with a small set of test images are presented. The results are promising and the methods work even on some poorly contrasted images. To compare the different image processing and recognition methods, a quality index is defined. On the test images the success of the presented methods is shown and the difference in recognition results can be measured using the introduced quality index.

A multi-factors approach for image quality assessment based on a human visual system model

In this paper, a multi-factor full-reference image quality index is presented. The proposed visual quality metric is based on an effective Human Visual System model. Images are pre-processed in order to take into account luminance masking and contrast sensitivity effects. The proposed metric relies on the computation of three distortion factors: blockiness, edge errors and visual impairments, which take into account the typical artifacts introduced by several classes of coders. A pooling algorithm is used in order to obtain a single distortion index. Results show the effectiveness of the proposed approach and its consistency with subjective evaluations.

An Association-Based Graphical Password Design Resistant to Shoulder-Surfing Attack

In line with the recent call for technology on Image Based Authentication (IBA) in JPEG committee [1], we present a novel graphical password design in this paper. It rests on the human cognitive ability of association-based memorization to make the authentication more user-friendly, comparing with traditional textual password. Based on the principle of zero-knowledge proof protocol, we further improve our primary design to overcome the shoulder-surfing attack issue without adding any extra complexity into the authentication procedure. System performance analysis and comparisons are presented to support our proposals.

Image blockiness evaluation based on Sobel operator

This paper presents a novel no-reference image blockiness index which exploits the properties of the Sobel operator. The blockiness index is a combination of two measures. The first quantifies the luminance variation of block boundaries pixels. The second quantifies the luminance variation of remaining pixels. Experimental results illustrating the performance of the proposed method show improvements over similar recently published methods.

Performance analysis of fractal modulation transmission over fast-fading wireless channels

Fractal modulation schemes have been under investigation for signal transmission over time-varying channels because of their advantages in data transmission at different frequency bands. This also allows efficient reception when channel conditions are varying by selecting the optimal frequency/time resolution based on the current channel condition. We present a performance analysis of fractal modulation transmission over Rician fast-fading channels in the presence of AWGN. A quadrature transmission scheme is simulated and compared, in terms of error robustness, to a QAM transmission system. Other papers analysing fractal modulation system performance do not consider time-varying channels, which are important as they represent the main configuration for communication systems based on this modulation technique. The novelty of our paper lies in the comparison of a fractal modulation system to a QAM one (core of the OFDM modulation technology, extensively used in broadcasting) using a testbed simulation environment where additive noise and fast fading are considered as typical error sources for transmission over wireless channels. Several wavelet families for a fractal modulation scheme have been considered and performance for each one measured; results reported show the effectiveness of the fractal modulation paradigm and confirm its effective utilization in data broadcasting.

An image browsing application based on JPEG XR

A method for browsing large compressed images over the Internet is presented. Images are compressed using a very recent coded file format, referred to as JPEG XR, designed primarily for storage of continuous-tone photographic images and currently at the beginning of the ISO/IEC standardization process. In the proposed method, region of interest specified by the user are progressively downloaded and displayed with an approach aiming to minimize the transferred information between the request and the image presentation. Experimental analysis show that the proposed method is an effective way for browsing large JPEG XR coded images.

QoE assessment of multimedia video consumption on tablet devices

In this paper we present a study aimed at assessing the Quality of Experience in video streaming when the user is employing a tablet devices. The study has been conducted on a database containing subjective assessment scores relative to 216 streaming sessions of video sequences encoded with H.264/AVC and corrupted by typical wireless channel transmission errors. Four 20sec-long video sequences at Common Intermediate Format (CIF) spatial resolution have been corrupted with 54 combinations of key parameters for the reference application: bitrate, packet loss rate, playout delay and transmission interruption. Subjective evaluations have been collected in compliance with ITU-T Recommendation P.910 through singlestimulus Absolute Category Rating (ACR) from 40 subjects. The videos were reproduced on two different tablet devices: on an Apple iPad 2 and on a Samsung Galaxy Tab GT-P1000. Subjective observations include the perceived quality considering all aspects of the fruition chain, from the coding to the environment and device specific issues. The evaluation results also provided several remarks that can be helpful in designing systems and applications for multimedia contents played back on tablets. The results show a good correlation between subjective observations and some impairments so that a simple QoE index is proposed. A correlation study between subjective assessment and objective metrics is also provided.

Interactive Image Viewing in Mobile Devices Based on JPEG XR

Services for high definition image browsing on mobile devices require a careful design since the user experience is heavily depending on the network bandwidth, processing delay, display resolution, image quality. Modern applications require coding technologies providing tools for resolution and quality scalability, for accessing spatial regions of interest (ROI), for reducing the domain of the coding algorithm decomposing large images into tiles. Some state-of-the-art technologies satisfying these requirements are the JPEG2000 and the JPEG XR. This paper presents the design of an interactive high resolution image viewing architecture for mobile devices based on JPEG XR. Display resolution, resolution scalability, image tiling are investigated in order to optimize the coding parameters with the objective to improve the user experience. Experimental tests are performed on a set of large images and comparisons against accessing the images without parameter optimization are reported.

High-frequency error recovery in JPEG XR coded images

Image data compressed with JPEG XR when transmitted over error-prone channels is severely distorted. In fact, due to the adaptive coding strategies used by the codec, even a single bit error causes a mismatch in the alignment of the reading position from the bitstream, leading to completely different images at the decoder side. We propose an extension to the JPEG XR algorithm, consisting in an error recovery process enabling the decoder to realign itself to the right bitstream position and to correctly decode the most part of the image. We have performed several experiments using different encoder parameter and different error probabilities while image distortion is measured by PSNR objective metric. The simplicity of the proposed algorithm adds very little computational overhead and seems very promising as confirmed by objective image quality results in experimental tests.

Error recovery in JPEG2000 image transmission

In this paper, the problem of bit-errors recovery in JPEG2000 images transmission is addressed, with particular attention to errors in the high-frequency components. In the HL and LH sub-bands, differently from the LL band, interpolation based recovering results tend to be often ineffective when more than a few adjacent wavelet coefficients are missing. The solution proposed is then to apply a wavelet patch repetition procedure by predicting the similitude between the contour structure in the damaged area and its surroundings. To this aim, the correlation in the spatial structure, that is the contour information, existing between different sub-bands has been analyzed and exploited. Accordingly, the patch used to conceal the corrupted region is that obtained by minimizing a correlation measure with the spatial structure extracted from an adjacent not corrupted subband. Objective and subjective improvements have been obtained.