Chapter 1 Definitions & Basics of Digital Image 1.Image 2.Digital Image 3.Raster 4. Vector 5.Image Editing 1

Basic Terminology The Image* An image: is an artifact, that has a similar appearance to some subject - usually a physical object or a person. – 2-D such as a photograph, screen display, and – 3-D such as a statue or hologram. 2

Basic Terminology The Image* The word image is also used in the broader sense of any two- dimensional figure such as – a map, – a graph, – a pie chart, – or an abstract painting. images can also be rendered manually, such as by – drawing, painting, carving, drawingpaintingcarving rendered automatically by – printing or computer graphics technology, printingcomputer graphics 3 * Feb.2014

Basic Terminology Moving Image* A moving image is typically a movie (film) or video, including digital video. It could also be an animated displayfilmvideodigital video 4 * Feb.2014

Basic Terminology DIGITAL IMAGES are electronic snapshots taken of a scene or scanned from documents, such as photographs, manuscripts, printed texts, and artwork. The digital image is sampled and mapped as a grid of dots or picture elements (pixels). Each pixel is assigned a tonal value (black, white, shades of gray or color), which is represented in binary code (zeros and ones). 5 Digital Imaging Tutorial, 2003

Basic Terminology An digital image: is a numeric representation (normally binary) of a 2-D image. Depending on whether the image resolution is fixed, it may be of vector or raster type. "digital image" usually refers to raster images also called bitmap images. 6

Basic Terminology An digital image: 7

Basic Terminology Raster Images. Raster images have a finite set of digital values, called picture elements or pixels. The digital image contains a fixed number of rows and columns of pixels. Pixels are the smallest individual element in an image, holding quantized values that represent the brightness of a given color at any specific point. 8

Basic Terminology Raster Images. Raster image type – Binary: is a digital image that has only two possible values for each pixel. – Grayscale: is an image in which the value of each pixel is a single sample, that is, it carries only intensity information. – Color: is a digital image that includes color information for each pixel. 9

Basic Terminology Raster Images. Raster image type 10

Basic Terminology Vector Images. Vector images resulted from mathematical geometry (vector). In mathematical terms, a vector consists of point that has both direction and length. Often, both raster and vector elements will be combined in one image; for example, in the case of a billboard with text (vector) and photographs (raster). 11

Basic Terminology Image Editing* include the processes of altering images, whether they be digital photograph, traditional photochemical photograph, or illustrations. 12 Illustration by Jessie Willcox SmithJessie Willcox Smith * Feb.2014

Basic Terminology Image Editing* Traditional analog image editing is known as photo retouching, using tools such as an airbrush to modify photographs, or editing illustrations with any traditional art medium. 13 * Feb.2014

Basic Terminology Image Editing* Graphic Software programs, which can be broadly grouped into vector graphics editors, vector graphics editors 14 * Feb.2014 A screenshot of the xfig vector graphics editorxfig A screenshot of the modern vector graphics editor InkscapeInkscape

Basic Terminology Image Editing* vector graphics formats (EPS) Encapsulated PostScript: Simply, an EPS file is a PostScript program, saved as a single file that includes a low-resolution preview "encapsulated" inside of it, allowing some programs to display a preview on the screen (PDF) Portable Document Format: used to represent documents in a manner independent of application software, hardware, and operating system (WMF) Windows Metafile: originally designed for Microsoft Windows in the 1990s. Windows Metafiles are intended to be portable between applications and may contain both vector graphics and bitmap components. It acts in a similar manner to SVG files.Microsoft Windowsvector graphicsbitmapSVG 15 * Feb.2014

Basic Terminology Image Editing* vector graphics formats (SVG) Scalable Vector Graphics or (VML) Vector Markup Language [xml file]: is an XML-based vector image format for two-dimensional graphics that has support for interactivity and animation. The SVG specification is an open standard developed by the World Wide Web Consortium (W3C) since 1999.XML vector image formatopen standardWorld Wide Web Consortium 16 * Feb.2014 VML Webart example

Basic Terminology Image Editing* raster graphics editors 17 * Feb.2014 A screenshot from the GIMP raster graphics editor.GIMP

Basic Terminology Image Editing* raster graphics formats – JPEG/JFIF JPEG (Joint Photographic Experts Group) is a compression method JPEG compression is (in most cases) lossy compression. – TIFF (Tagged Image File Format) format is a flexible format that normally saves 8 bits or 16 bits per color (red, green, blue) for 24-bit and 48-bit totals. Can be lossy and lossless. – GIF (Graphics Interchange Format) is limited to an 8- bit palette, or 256 colors. 18 * Feb.2014

Basic Terminology Image Editing* raster graphics formats – PNG (Portable Network Graphics) file format was created as the free, open-source successor to the GIF. Supports true color (16 million colors). – BMP (Windows bitmap) handles graphics files within the Microsoft Windows OS. Typically, BMP files are uncompressed, hence they are large; the advantage is their simplicity and wide acceptance in Windows programs. – WebP is a new image format that uses lossy compression. It was designed by Google to reduce image file size to speed up web page loading 19 * Feb.2014

Basic Terminology Image Editing* raster graphics formats – JPEG XR (New JPEG standard based on Microsoft HD Photo) – TGA (TARGA) – ILBM (InterLeaved BitMap) – IMG (Graphical Environment Manager image file; planar, run-length encoded) – PCX (Personal Computer eXchange) – ECW (Enhanced Compression Wavelet) – IMG (ERDAS IMAGINE Image) 20 * Feb.2014

Basic Terminology Image Editing* 3D modelers 21 * Feb.2014 All previous tools are the primary tools with which a user may manipulate, enhance, and transform images. Many image editing programs are also used to render or create computer art from scratch. 3D computer graphics software