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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.
Characterization of the piezoelectric lead zirconate titanate catalyzed degradation of rhodamine B and methylene blue dyes by smartphone-based colorimetry
Published in Instrumentation Science & Technology, 2021
Vishvendra Pratap Singh, Ankit Susaniya, S. C. Jain, Rahul Vaish
A typical RGB image is made up of 8-bit color channels of red, green, and blue. Different combinations of these colors produce a wide spectrum of colors and 256 various intensities (ranges from 0 to 255 for each color channel). Therefore, a total of 2563 color combinations are possible with different RGB values. For example, R = G = B = 0 signifies pure black, while R = G = B = 255 produces pure white. Between pure black and white, there are many unique combinations of colors are possible that may be correlated with respective intensities of their solutions from which unknown concentrations may be determined. Therefore, in this article, we have demonstrated piezocatalytic dye degradation using a simple portable setup based on colorimetry using a smartphone.