Image and Sound Editing

Raed S. Rasheed2012

Image

• Image.• Digital image.– Raster images.– Vector Images.– Stereo Images.– Image File Formats• Lossless compression • Lossy compression

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.

Digital Image

• 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.

• (Raster, Vector, and Stereo) Images.

Digital Image

Digital Image

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.

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.

Raster Images

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).

Stereo Images

• Stereoscopy (also called stereoscopic or 3-D imaging) refers to a technique for creating or enhancing the illusion of depth in an image by presenting two offset images separately to the left and right eye of the viewer. These 2-D images are then combined in the brain to give the perception of 3-D depth.

Image File Formats

• Image file formats are standardized means of organizing and storing digital images. Image files are composed of either pixels, vector (geometric) data, or a combination of the two.

Image File Formats

• Image file compression– Lossless compression algorithms reduce file size without

losing image quality, though they are not compressed into as small a file as a lossy compression file.

– Lossy compression algorithms take advantage of the inherent limitations of the human eye and discard invisible information. Most lossy compression algorithms allow for variable quality levels (compression) and as these levels are increased, file size is reduced.

Image File Formats

• Raster 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.

Image File Formats

• Raster formats– PNG (Portable Network Graphics) file format was created

as the free, open-source successor to the GIF. Supports truecolor (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

Image File Formats

• Raster 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)

Image File Formats

• Raster formats– SID (multiresolution seamless image database, MrSID)– CD5 (Chasys Draw Image)– FITS (Flexible Image Transport System)– PGF (Progressive Graphics File)– XCF (eXperimental Computing Facility format, native

GIMP format)– PSD (Adobe PhotoShop Document)– PSP (Corel Paint Shop Pro)

Image File Formats

• Vector formats– CGM (Computer Graphics Metafile) is a file format

for 2D vector graphics.– SVG (Scalable Vector Graphics) is an open

standard created and developed by the W3C.

Image File Formats

• Stereo formats– MPO (Multi Picture Object) (.mpo) format consists

of multiple JPEG images (Camera & Imaging Products Association) (CIPA).

– PNS PNG Stereo (.pns) format consists of a side-by-side image based on PNG (Portable Network Graphics).

– JPS JPEG Stereo (.jps) format consists of a side-by-side image format based on JPEG.