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Security and Cryptography in Images and Video Using Elliptic Curve Cryptography (ECC)
Published in S. Ramakrishnan, Cryptographic and Information Security, 2018
An image is defined as a collection of values, where value denotes the intensity of light in the form of an array or matrix. This matrix could be two dimensional in the case of black and white images or grayscale images, or it may be a three-dimensional matrix, as in case of a color image (RGB image). There is a little difference between black and white and grayscale images. In black and white image, there are only two colors, either black or white; on the other hand, a grayscale image contains values in between 0 to 255 where 0 is completely black and 255 is completely white. For example, an 8-bit grayscale image can have up to 255, or 28 shades of black and white, (i.e., 8-bit color depth). A true color or RGB image has a 24-bit color depth which is almost 16 million colors, or 224. Images can be stored in JPEG, PNG, TIFF, BMP, etc. formats. All these formats differ in terms of compression technique, output size of the compressed image, and visual depth of the compressed image. In image compression lossless compression means an image can be reconstructed accurately from the compressed image. Formats like PNG, TIFF, and BMP support lossless compression while JPEG is lossy compression. Table 6.1 shows the difference in various image formats.
Basic Fundamentals, Definitions, and Key Terms
Published in Fred Huffman, Practical IP and Telecom for Broadcast Engineering and Operations, 2013
Color television pictures are made from primary color signals derived from red, green, and blue signals produced by pickup devices, originally scanning electron tubes and, more recently, charge couple device (CCD) solid-state sensors packaged in various forms. Basically, signals from the three sensors are processed to make a monochrome picture that monochrome receivers can detect and display, while additional detection and decoding circuitry in color receivers extract the color information and “paint” it on, or into monochrome pictures. Color television leverages the basics of color derived from combinations of the color primaries (RGB) into three secondary colors—cyan, magenta, and yellow. With appropriate mixing, it is also possible to make black, white, and a range of monochrome tones in between, also called a grayscale. Television had its own version of luminance and chrominance. The ability to include color information in the same channel by simply multiplexing the three colors into a signal that enables recovery and representation of the original image has been extended to describing composite color signals as an example of 6:1 compression, 2:1 for interlaced scan, and 3:1 for RGB color into chroma.
Formatting and Analysis of Thermal Images
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
The fixed-span technique sets the caliper span to a fixed value. This technique may be used for both color and greyscale images. The fixed span is usually set to 8°C (14.4°F) for breast exams. Neuromuscular exams typically use a 10°C (18°F) span, while sports science thermography may require a 14°C (25.2°F) fixed span.15 This fixed span is then moved up or down the radiometric temperature scale to best visualize the ROI. Fixed-span formatting techniques can be traced back to the older infrared scanner technology, but are still used for clinical studies as well as research reports. See Figure 7.12 to set up a moveable Fixed Span Color Caliper in a typical infrared display program.
Bio-inspired knitted fabric development using 3D modelling and image processing
Published in The Journal of The Textile Institute, 2020
Manoj Kumar Imrith, Satyadev Rosunee, Roshan Unmar
In computer vision, greyscale images are essentially used over coloured images for extracting descriptions because greyscale reduces computational processing and retain all details of information (Corl, Garland, Lawler, & Fishman, 2002). Image binarization also known as thresholding can be performed either locally or globally (Gonzalez & Woods, 2018). Global threshold weighed up only a single binarize value for the whole image (Otsu, 1979). Local Adaptive Threshold (LAT) computes the threshold value for each pixel on the source of information held in environs of the pixels (Jain & Trier, 1995). Niblack (1986) and Parker (1991) discussed the applications of the LAT and Morphological Threshold (MT) methods. Currently, the common approach to capture and assess images of textile fabrics includes the use of a digital camera and digital image processing (Banumathi & Nasira, 2012; Huang & Fu, 2018; Szmyt & Mikolajczyk, 2010; Zaouali, Msahli, & Sakli, 2010).
On the Effectiveness of Image Processing Based Malware Detection Techniques
Published in Cybernetics and Systems, 2022
Byte Plot: Executable binaries represented as a sequence of bits are grouped into 8-bit vectors, with each byte holding values ranging from 0 to 255. These values could, evidently, be mapped as brightness values of pixels. A grayscale image is created by converting 0 to black, 255 to white, and all other values in between to different gray levels. The byte value is plotted from left to right of the image, wrapping up at the end of each row. The process is depicted in Figure 4. The width of the images is usually kept constant, and height is varied according to the executable file size based on the recommendations from Nataraj et al. (2011).
Image Enhancement and Implementation of CLAHE Algorithm and Bilinear Interpolation
Published in Cybernetics and Systems, 2022
Venkatesh S., John De Britto C., Subhashini P., Somasundaram K.
This methodology illustrates the following steps. As shown in Figure 2, the CLAHE algorithm, bilinear interpolation, and contrast stretching are involved. During the capture of an image, images with noise may occur due to improper lighting. It is also possible to use grayscale images as well as colored images. Images with noise are allowed if they are low quality.