• IEMEK Journal of Embedded Systems and Applications
• /
• v.4 no.3
• /
• pp.103-111
• /
• 2009

Software update has been regarded as one of fundamental functions in wireless sensor networks. It can disseminate a delta-image between a current software image operating on a sensor node and its new image in order to reduce an update image(transmission data) size, resultantly saving energy. In addition, code-banking capability of micro-controllers can decrease the update image size. In order to maximize the efficiency of the software update, the proposed scheme exploits both the delta-image and the code-banking at the same time. Besides, it additionally delivers a recovery delta-image to properly handle abnormal conditions, such as message corruptions and unexpected power-off during the update.

• Journal of Korean Ophthalmic Optics Society
• /
• v.5 no.2
• /
• pp.175-180
• /
• 2000

The intensity of beam of light entering near the pupil edge is less than when it passes through the center of the pupil, this phenomenon is known as the Stiles-Crawford effect. In this paper, we investigate the variation in the shape of confusion circle when the real amplitude distribution of incident beam in pupil area is shifted to any direction by effects. The shape of confusion circle on the image surface is rotational symmetric when the real amplitude distribution of incident beam in pupil area isn't shifted, and the shape of confusion circle on the image surface is asymmetric as ellipse when the real amplitude distribution of incident beam in pupil area is shifted. The shifted direction of the real amplitude distribution of incident beam in pupil area equals the major axis direction of confusion circle on the image surface. When the shifted direction of the real amplitude distribution of incident beam in pupil area changes from ${\Delta}{\phi}$ to ${\Delta}{\phi}+{\pi}$, the intensity distributions and the shapes of confusion circle on the image surface for ${\Delta}{\phi}$ equals that for ${\Delta}{\phi}+{\pi}$. We know from above results that the influences of ${\Delta}{\phi}+{\pi}$ and ${\Delta}{\phi}+{\pi}$ cases on the image quality of optical system equal.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.3
• /
• pp.669-675
• /
• 2005

This paper proposes coordinates transformation and calibration algorithm using 3D parabolic coordinate transformation and delta-bar-delta neural algorithm for the omni-directional image captured by catadioptric camera. Experimental results shows that the proposed algorithm has accuracy and confidence in coordinate transformation which is sensitive to environmental variables.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.2 s.46
• /
• pp.77-82
• /
• 2007

In this paper, we proposed the image processing techniques for extracting the cracks in a concrete surface crack image and the enhanced Max-Min neural network for recognizing the directions of the extracted cracks. The image processing techniques used are the closing operation or morphological techniques, the Sobel masking for extracting for edges of the cracks, and the iterated binarization for acquiring the binarized image from the crack image. The cracks are extracted from the concrete surface image after applying two times of noise reduction to the binarized image. We proposed the method for automatically recognizing the directions of the cracks with the enhanced Max-Min neural network. Also, we propose an enhanced Max-Min neural network by auto-tuning of learning rate using delta-bar-delta algorithm. The experiments using real concrete crack images showed that the cracks in the concrete crack images were effectively extracted and the enhanced Max-Min neural network was effective in the recognition of direction of the extracted cracks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.7
• /
• pp.1428-1436
• /
• 2012

This paper presents the delta image composition methods using Depth-Image-Based Rendering (DIBR) for 3D stereoscopic broadcasting for the low bandwidth mobile DMB broadcasting system. With DIBR, a left and depth images are transmitted to a mobile device, which restores the right view, whose quality may be poor. This paper describes delta image composition methods for the restoration while minimizing the amount of the transmitted data.

• Journal of The Korean Astronomical Society
• /
• v.33 no.2
• /
• pp.89-95
• /
• 2000

As an efficient method to detect blending of general gravitational microlensing events, it is proposed to measure the shift of source star image centroid caused by microlensing. The conventional method to detect blending by this method is measuring the difference between the positions of the source star image point spread function measured on the images taken before and during the event (the PSF centroid shift, ${\delta}{\theta}$c,PSF). In this paper, we investigate the difference between the centroid positions measured on the reference and the subtracted images obtained by using the difference image analysis method (DIA centroid shift, ${\delta}{\theta}$c.DIA), and evaluate its relative usefulness in detecting blending over the conventional method based on ${\delta}{\theta}$c,PSF measurements. From this investigation, we find that the DIA centroid shift of an event is always larger than the PSF centroid shift. We also find that while ${\delta}{\theta}$c,PSF becomes smaller as the event amplification decreases, ${\delta}{\theta}$c.DIA remains constant regardless of the amplification. In addition, while ${\delta}{\theta}$c,DIA linearly increases with the increasing value of the blended light fraction, ${\delta}{\theta}$c,PSF peaks at a certain value of the blended light fraction and then eventually decreases as the fraction further increases. Therefore, measurements of ${\delta}{\theta}$c,DIA instead of ${\delta}{\theta}$c,PSF will be an even more efficient method to detect the blending effect of especially of highly blended events, for which the uncertainties in the determined time scales are high, as well as of low amplification events, for which the current method is highly inefficient.

• Journal of Sensor Science and Technology
• /
• v.30 no.4
• /
• pp.223-228
• /
• 2021

This work presents a low-power CMOS image sensor (CIS) with a multi-column-parallel (MCP) readout structure while focusing on improving its performance compared to previous works. A delta readout scheme that utilizes the image characteristics is optimized for the MCP readout structure. By simply alternating the MCP readout direction for each row selection, additional memory for the row-to-row delta readout is not required, resulting in a reduced area of occupation compared to the previous work. In addition, the bias current of a pre-amplifier in a successive approximate register (SAR) analog-to-digital converter (ADC) changes according to the operating period to improve the power efficiency. The prototype CIS chip was fabricated using a 0.18-㎛ CMOS process. A 160 × 120 pixel array with 4.4 ㎛ pitch was implemented with a 10-bit SAR ADC. The prototype CIS demonstrated a frame rate of 120 fps with a total power consumption of 1.92 mW.

• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.2
• /
• pp.185-194
• /
• 2012

Purpose: The changes of phoria and subjective asthenopia before and after viewing were compared based on 2D image and two ways of 3D images, and presented for references of 3D image watching and production. Methods: Change in phoria was measured before and after watching 2D image, 3D-FPR and 3D-SG images for 30 minutes with a target of 41 university students at 20-30 years old (male 26, female 15). Paired t-test and Pearson correlation between changed phoria and subjective symptoms which were measured using questionnaires were evaluated by before and after watching each images. Results: Right after watching 2D image, exophoria was increased by 0.5 $\Delta$, in distance and near, but it was not a significant level. Right after watching 3D image, exophoria was increased by 1.0~1.5 $\Delta$, and 1.5~2.0 $\Delta$, in distance and near, respectively when compared with before watching. In the significant level, exophoria tended to increase. Changes in near was increased more by 0.5 $\Delta$, compared with those in distance. Changes based on way of 3D-FPR and 3D-SG image were less than 0.5 $\Delta$, and there was almost no difference. In terms of visual subjective symptoms, eye strain was increased in 3D image compared with that in 2D image. In addition, there was no difference depending on way of image. In terms of Pearson correlation between phoria change and eye strain, as exophoria was increased, eye strain was increased. Conclusions: Watching 3D image increased eye strain compared with watching 2D image, and accordingly exophoria tended to increase.

• Journal of radiological science and technology
• /
• v.25 no.1
• /
• pp.77-81
• /
• 2002

The purpose of this study is to examine quantitatively the relationship between visual image quality and degradation In spatial resolution for a gamma camera by the increase in distance from collimator. The relationship between the portion(p) of images identified the difference of image quality and the difference(${\Delta}FWHM$) in FWHM between paired images was showed in a sigmoid curve. Using Dendy's method, minimum level to be correctly identified the difference of Image duality on three out of four occasion(p=0.75) was corresponded to 0.4 mm in ${\Delta}FWHM$. Using fuzzy theory, the level to be identified the difference of image quality was examined under various conditions. The truth-value of fuzzy sets-degraded or slightly degraded and not-degraded in image quality between palled Images-was gained the peak at 0.5 mm of ${\Delta}FWHM$. It was founded that changes of $0.4{\sim}0.5\;mm$ in FWHM-corresponding about 2 cm distance from collimator could be sufficiently identified in the difference of image quality.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.11
• /
• pp.2143-2149
• /
• 2007

Visual Cortex Stimulator is among artificial retina prosthesis for blind man, is the method that stimulate the brain cell directly without processing the information from retina to visual cortex. In this paper, we propose image construction and recognition model that is similar to human visual processing by recognizing the feature data with orientation information, that is, the characteristics of visual cortex. Back propagation algorithm based on Delta-bar delta is used to recognize after extracting image feature by Kirsh edge detector. Various numerical patterns are used to analyze the performance of proposed method. In experiment, the proposed recognition model to extract image characteristics with the orientation of information from retinal cells to visual cortex makes a little difference in a recognition rate but shows that it is not sensitive in a variety of learning rates similar to human vision system.