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Digital images are numerical representations of two-dimensional images, primarily classified into raster and vector types. Raster images (bitmap) consist of a grid of pixels, each representing colors based on primary color combinations. Vector graphics use geometric primitives such as points and shapes defined by mathematical expressions. Key concepts include pixels, channels, and image depth, which affects the richness of color and detail. This overview provides insights into the fundamentals of digital imaging and how they are manipulated, particularly in software like MATLAB.
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Image Definition A digital image is a numeric representation (normally binary) of a two-dimensional image. Depending on whether or not the image resolution is fixed, it may be of vector or raster type. Without qualifications, the term "digital image" usually refers to raster images also called bitmap images.
Vectors Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical expressions, to represent images in computer graphics.
Rasters It is a data structure representing a generally rectangular grid of pixels
Black To White 0 26 52 78 104 130 156 182 208 234 255
Primary Colors For human applications, three primary colors are usually used, since human color vision is trichromatic
Pixel In digital imaging, a pixel or picture element is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled.
Channels Pixels are made of combinations of primary colors. A channel in this context is the grayscale image of the same size as a color image, made of just one of these primary colors.
Digital Image Formal Definition An image may be defined as a two dimensional function f(x , y), where x and y are spatial coordinates and the amplitude f at any pair of coordinates is called the intensity or gray level of the image at that point.
Image Depth 2 bit 4 bit 1 bit
IMAGE DEPTH (contd.) 8 bit 24 bit
IMAGE AS A MATRIX Lets Move To Matlab
Commands imread(‘image filename’) – Loads image as a matrix imshow(‘variable’) – Shows the image in the Matlab image viewer