Number Of Pixel Values Research Articles

Chaotic Image Encryption Algorithm Based on Bit-Combination Scrambling in Decimal System and Dynamic Diffusion

In this paper, an image encryption algorithm based on bit-combination scrambling and dynamic diffusion is proposed based on multiple chaotic systems. First, the plaintext image is scrambled. On the basis of the decimal system, the pixel value of the gray-scale plaintext image is divided into three groups: units, tens, and hundreds' digit. Each group performs different rounds of Arnold mapping, and the parameters of the Arnold mapping and the number of mapping wheels are determined by the plaintext image. The scrambled image is generated by combination. This algorithm avoids the periodicity of Arnold mapping. Second, the dynamic diffusion operation is designed. This operation can start from any position of the plaintext pixel value and combine chaotic sequence to do XOR around this point. Therefore, it has N modes of diffusion, where N is the number of pixel values. Third, this method is extended to color image encryption. The comparison test results show that this method has better security and can resist common attack methods.

Aplikasi Otentikasi Citra Digital Dengan Metode Adaptive Data Hiding

Problems that often occur in internet services make data security not guaranteed. To provide content authentication and duplicate protection from digital data, two complementary techniques have been developed, namely encryption and watermarks. Encryption techniques are used to secure digital data during transmission from sender to receiver. Because digital images can be easily reproduced, cryptosystems cannot solve this problem perfectly. The second security measure that completes encryption is to attach a secret signal, a watermark, directly to the original data so that it remains available during use. Watermarking cannot prevent duplication, modification and distribution of digital media by itself, so it must be combined with cryptography. Embedding is done by modifying the average pixel intensity value of each block in the range determined by the contrast value for a particular block. This reduces the effect of modification as felt by the human eye. The extraction procedure calculates and compares the number of pixel values for blocks of the original image and watermark. The results show the robustness of the scheme towards general image processing operations such as cropping, modification, low pass filters, median pass filters, minimized and lossy JPEG compression with various quality index factors. The results also illustrate that the watermark is safe, restored and recognized even after the watermark image has been damaged, forged and modified by a general image processing operation. A comparative study of the scheme proposed with the existing scheme has also been carried out to observe the strength of the scheme.

174 ULTRASOUND BIOMICROSCOPIC IMAGE ATTRIBUTES OF OVARIAN FOLLICLES IN HEIFERS

High-resolution ultrasound biomicroscopy (UBM) with high-frequency transducers (20 to 50 MHz) has enabled imaging of small antral follicles (<1 mm) and acoustic characterisation of the follicular antrum and wall. Quantitative echotextural analysis of the images generated by UBM provides detailed functional information about the granulosa and theca layers of follicle walls. The objectives of our study were to compare biomicroscope image echotextures between dominant and largest subordinate follicles during the first follicular wave and to characterise UBM attributes of the ovulatory follicle. Hereford crossbred heifers (14 to 16 months old, n = 12) were used. Ovarian examinations were performed transvaginally from Day –4 or –3 (Day 0 = ovulation) to Day 10 using a UBM imaging instrument (Vevo 660; Visual Sonics Inc., Toronto, Canada) equipped with a 25-MHz end-fire transducer. Echotextural assessment was performed by spot metrics of the follicle antrum and follicle wall by using a series of custom-developed computer algorithms optimized for ultrasonography (Synergyne©, Version 2.8, WHIRL, Saskatoon, SK, Canada). Although subordinate and dominant follicles development were tracked from Day –2 (around 1 mm in diameter) to Day 10, the ovulatory follicle was tracked only from Day –4 to ovulation. All data were analysed by analysis of variance for repeated measures using the Mixed procedure (Littell et al. 1998) in the Statistical Analysis System software package (SAS version 8.2 for MS Windows; SAS Institute Inc., Cary, NC, USA). No differences were detected between dominant and largest subordinate follicle in the mean pixel value (MPV) or pixel heterogeneity (PH) of the antrum. However, the MPV of the wall of dominant follicles was greater and PH tended to be greater than that of the largest subordinate follicles (P = 0.05 and P = 0.1, respectively). This result could be evidence that the dominant follicle would be healthier. The PH of the wall the ovulatory follicle decreased (P = 0.03) from Day –4 to Day –1; however, no changes in MPV were observed. Similarly, no changes were detected in MPV or PH of the follicular antrum. The loss of granulosa cells from the follicular wall can explain, at least in part, the decrease in mean pixel value and pixel heterogeneity of the follicular wall detected in ovulatory follicles. Moreover, morphologic changes indicative of atresia are typically represented by high values of number of pixel values. In conclusion, although no differences in antral characteristics of dominant v. subordinate follicles were detected, mean pixel value and pixel heterogeneity of the follicular wall were higher in dominant follicles, and pixel heterogeneity of follicular wall of ovulatory follicles decreased over days. Quantitative pixel analysis from follicular wall images using UBM could be applied to evaluate follicles in live animals. However, more studies using this technique are necessary. Research was supported by NSERC and CIHR. Luiz Pfeifer was supported by CAPES from Ministry of Education, Brazil.