This PDF file contains the editorial “Image Processing: Principles and Applications” for JEI Vol. 15 Issue 03

Image Processing - Principles and Applications

We propose an effective color filter array (CFA) interpolation method for digital still cameras (DSCs) using a simple image model that correlates the R,G,B channels. In this model, we define the constants K/sub R/ as green minus red and K/sub B/ as green minus blue. For real-world images, the contrasts of K/sub R/ and K/sub B/ are quite flat over a small region and this property is suitable for interpolation. The main contribution of this paper is that we propose a low-complexity interpolation method to improve the image quality. We show that the frequency response of the proposed method is better than the conventional methods. Simulation results also verify that the proposed method obtain superior image quality on typical images. The luminance channel of the proposed method outperforms by 6.34-dB peak SNR the bilinear method, and the chrominance channels have a 7.69-dB peak signal-to-noise ratio improvement on average. Furthermore, the complexity of the proposed method is comparable to conventional bilinear interpolation. It requires only add and shift operations to implement.

/pdf/effective-color-interpolation-in-ccd-color-filter-arrays-307ju0suad.pdf

Effective color interpolation in CCD color filter arrays using signal correlation

This paper presents an adaptive demosaicing algorithm. Missing green samples are first estimated based on the variances of the color differences along different edge directions. The missing red and blue components are then estimated based on the interpolated green plane. This algorithm can effectively preserve the details in texture regions and, at the same time, it can significantly reduce the color artifacts. As compared with the latest demosaicing algorithms, the proposed algorithm produces the best average demosaicing performance both objectively and subjectively

/pdf/color-demosaicing-using-variance-of-color-differences-ehgjony42a.pdf

Color Demosaicing Using Variance of Color Differences

http://www.dmi.unict.it/~battiato/download/BattiatoBGS.pdf

A locally adaptive zooming algorithm for digital images

This paper explores the possibility of using multispectral iris information to enhance the recognition performance of an iris biometric system. Commercial iris recognition systems typically sense the iridal reflection pertaining to the near-infrared (IR) range of the electromagnetic spectrum. This work examines the iris information represented in the visible and IR portion of the spectrum. It is hypothesized that, based on the color of the eye, different components of the iris are highlighted at multiple wavelengths. To this end, an acquisition procedure for obtaining co-registered multispectral iris images associated with the IR, Red, Green and Blue wavelengths of the electromagnetic spectrum, is first discussed. The components of the iris that are revealed in multiple spectral channels/wavelengths based on the color of the eye are studied. An adaptive histogram equalization scheme is invoked to enhance the iris structure. The performance of iris recognition across multiple wavelengths is next evaluated. Experiments indicate the potential of using multispectral information to enhance the performance of iris recognition systems.

Multispectral Iris Analysis: A Preliminary Study51

This paper discusses the interpolation technique applied to the Bayer primary color method, used frequently as the pixel structure of CCD image sensors for digital still cameras. Eight typical types of interpolation methods are discussed from three viewpoints: the characteristics of the interpolated images, the processing time required to realize their methods based on a 32-bit MCU for embedded applications, and the quality of the resultant images. In terms of reducing the occurrences of pseudocolor and achieving good color restoration, the linear interpolation method taking G's correlation determined by using R/B pixels into consideration was found to be excellent. The measured machine cycle of the interpolation methods was approximately 46 cycles per pixel. Therefore, every method was able to interpolate a VGA-size image in approximately 0.2 seconds with the MCU operating at 60 MHz. In terms of the S/N ratio, a good image quality was obtained through the linear interpolation methods, even with shorter processing time. Based on these results it is concluded that the linear interpolation method, which takes correlation into consideration, is the most suitable for consumer product applications such as digital still cameras.

Software pixel interpolation for digital still cameras suitable for a 32-bit MCU

This paper describes a fast MP3 algorithm for a 32-bit microcontroller unit (MCU) with DRAM to realize a real-time MP3 software decoder. Effective methods of reducing the amount of operations by using the IMDCT coefficients' symmetry and appropriate multiplication size, and storing data to use the DRAM effectively are proposed. As a result, the proposed methods make it possible to cut the processing speed requirement in half and a decoding time of approximately 20 msec per frame for joint stereo data with a sampling frequency of 44.1 kHz has been obtained, that is to say, real-time decoding can be realized.

A fast MPEG-audio layer III algorithm for a 32-bit MCU

An MPEG-1 audio layer III decoding device, which can perform fast decoding of MP3 by performing fast inverse quantization of Huffman code data, includes a bit stream decomposing portion for decomposing an input bit stream of MP3 into side information including bit allocation information and Huffman table information, a scale factor and Huffman code data; a scale factor decoder for decoding the scale factor decomposed from the bit-stream based on the side information; a Huffman decoder for decoding the Huffman code data decomposed from the bit-stream based on the Huffman table information included in the side information; a zero detecting portion for detecting a band of the Huffman code data all providing values of zero; an inverse quantizer for performing inverse quantizing processing on the Huffman code data based on the output of the zero detecting portion, the side information, the scale factor and the Huffman code data; and a hybrid filter bank portion for inversely mapping and decoding the output of the inverse quantizer into a time region signal.

MPEG-1 audio layer III decoding device achieving fast processing by eliminating an arithmetic operation providing a previously known operation result

This paper proposes a remote controller (RC for short) with high usability. Nowadays, RCs play an important role in improving the usability of home appliances. The conventional RCs have mainly two drawbacks-the increase in the number of the buttons on the control panel and inflexible macro functions. Furthermore, the RC is associated with each appliance, RCs are scattered in a room. To overcome some problems, a bidirectional RC has been proposed. However, this RC only simulates multiple RCs using downloaded menus. It supplies no intelligent operations. The RC proposed in this paper manipulates multiple appliances with an XML-based touchpanel LCD and agent-based bidirectional communication. It carries out user-friendly integration of RCs using XML technology. Advanced/flexible interoperations among home appliances can also be established via agent scripts. The RC software is implemented on an 32 bit embedded MCU and experimental results ensure its high usability and flexibility.

An agent-based bidirectional intelligent remote controller

This paper describes a new software solution for DCT-based JPEG image compression using a 32-bit microcontroller unit (MCU) with parallel execution (dual issue). Taking the constraints of the MCU hardware resources into consideration, various fast algorithms for DCT are investigated. As a result, it is concluded that the optimal fast algorithm for MCUs capable of parallel execution differs from the optimal algorithm for MCUs which do not support parallel execution. Comparing the number of JPEG image compression cycles using software on MCUs with and without parallel execution capability, it is concluded that the processing speed of the latter type of MCU is approximately 30% higher than the former type. When this former processing speed is applied to a 640/spl times/480 (VGA-size) YCbCr image in 4:2:2 format, compression can be performed in about 0.15 seconds (using a 100 MHz MCU with parallel execution capability).

Tadashi Sakamoto

Papers

Software pixel interpolation for digital still cameras suitable for a 32-bit MCU

A fast MPEG-audio layer III algorithm for a 32-bit MCU

MPEG-1 audio layer III decoding device achieving fast processing by eliminating an arithmetic operation providing a previously known operation result

An agent-based bidirectional intelligent remote controller

Software JPEG for a 32-bit MCU with dual issue