Pixel resolutionThe term resolution is often used for a pixel count in digital imaging, even though American,Japanese, and international standards specify that it should not be so used, at least in thedigital camera field. An image of N pixels high by M pixels wide can have any resolution lessthan N lines per picture height, or N TV lines. But when the pixel counts are referred to asresolution, the convention is to describe the pixel resolution with the set of two positiveinteger numbers, where the first number is the number of pixel columns (width) and thesecond is the number of pixel rows (height), for example as 7680 by 4320. Another popularconvention is to cite resolution as the total number of pixels in the image, typically given asnumber of megapixels, which can be calculated by multiplying pixel columns by pixel rowsand dividing by one million. Other conventions include describing pixels per length unit orpixels per area unit, such as pixels per inch or per square inch. None of these pixelresolutions are true resolutions, but they are widely referred to as such; they serve as upperbounds on image resolution.According to the same standards, the number of effective pixels that an image sensor ordigital camera has is the count of elementary pixel sensors that contribute to the finalimage, as opposed to the number of total pixels, which includes unused or light-shieldedpixels around the edges.Below is an illustration of how the same image might appear at different pixel resolutions, ifthe pixels were poorly rendered as sharp squares (normally, a smooth image reconstructionfrom pixels would be preferred, but for illustration of pixels, the sharp squares make thepoint better).VECTOR AND RASTER IMAGESRaster Graphics (commonly called bitmap images) are made of pixels. Photographs arean example of a bitmap image. They have a fixed resolution and cannot be resizedlarger without losing quality.Common bitmap file formats end in: .gif .jpg .png .tiff & .bmpBitmap images typically have much larger file sizes than the same image as a vectorgraphic so they are often compressed to reduce their size. Bitmap images can beconverted from one format to another with programs such as Photoshop.Vector Graphics are images that have been created in a drawing program such asAdobe Illustrator. They use paths to create lines and curves at connecting pointscalled "nodes" to store the graphics information mathematically. Vector art isresolution independent; whether you enlarge or shrink the image, the output qualityis never compromised. This is why logos should always be created in vector artformat. Common file formats for vector art used in the commercial printing industryinclude: .ai .eps & .pdf
BMP - Short for "Bitmap." It can be pronounced as "bump," "B-M-P," or simply a "bitmap image." The BMPformat is a commonly used raster graphic format for saving image files. It was introduced on the Windowsplatform, but is now recognized by many programs on both Macs and PCs.PNG - which can be pronounced "ping" or "P-N-G," is a compressed raster graphic format. It is commonly usedon the Web and is also a popular choice for application graphics.GIF -The letters "GIF" actually stand for "Graphics Interchange Format," but you dont need to remember that.What you should know is that a GIF is a compressed image file format. GIF images use a compression formulaoriginally developed by CompuServe.TIFF - Stands for "Tagged Image File Format." It is graphics file format created in the 1980s to be the standardimage format across multiple computer platforms. The TIFF format can handle color depths ranging from 1-bitto 24-bit.JPG - The term actually stands for "Joint Photographic Experts Group," because that is the name of thecommittee that developed the format. But you dont have to remember that because even computer nerdswill think youre weird if you mention what JPEG stands for. Instead, remember that a JPEG is a compressedimage file format.PSD - Image file created by Adobe Photoshop, a professional image-editing program; may include image layers,adjustment layers, layer masks, annotation notes, file information, keywords, and other Photoshop-specificelements.PDF - Cross-platform document created by Adobe Acrobat or a program with the Acrobat plug-in; commonlyused for e-mail attachments or for saving publications in a standard format for viewing on multiple computers;usually created from another document instead of from scratch; can be edited with Adobe Acrobat, acommercial program.EPS - PostScript (.PS) file that may contain 2D vector graphics, bitmap images, and text; may also include anembedded preview image in bitmap format; can be placed within another PostScript document.AI - Drawing created with Adobe Illustrator, a vector graphics editing program; composed of paths connectedby points, rather than bitmap image data; commonly used for logos and print media.COMPRESSIONCompression, or "data compression," is used to reduce the size of one or more files. When afile is compressed, it takes up less disk space than an uncompressed version and can betransferred to other systems more quickly. Therefore, compression is often used to savedisk space and reduce the time needed to transfer files over the Internet.There are two primary types of data compression:1. File Compression2. Media CompressionFile compression can be used to compress all types of data into a compressed archive. Thesearchives must first be decompressed with a decompression utility in order to open theoriginal file(s). Media compression is used to save compressed image, audio, and video files.Examples of compressed media formats include JPEG images, MP3 audio, and MPEG video
files. Most image viewers and media playback programs can open standard compressed filetypes directly.VIDEO CAPTURE DEVICESConverting analog video signals, such as those generated by a video camera, into a digitalformat and then storing the digital video on a computers mass storage device. Videocapture from analog devices requires a special video capture card that converts the analogsignals into digital form and compresses the data. There are also digital video devices thatcan capture images and transfer them to a computer via a standard serial or parallelinterface.OPTIMISINGFor imagery, optimisation involves choosing a suitable graphic compression format.Compression reduces the image filesize and consequently the time it takes to download anddisplay in a browser. Common compression types include GIF, JPEG and PNG. Manycompression formats reduce filesize by removing information from the image(downsampling). For example, the JPEG format reduces overall tonal range to reducefilesize—reducing the tonal range means that highlights and shadows become lesspronounced.Reducing the number, and filesize of the images can be a significant issue for websites withlarge subscriber bases such as news sites. Site owners are charged for the amount ofinformation (data) downloaded from their sites (traffic). The more popular the site andlarger the images the greater the traffic costs.STORAGE AND ASSET MANAGEMENTSTORAGE AND ASSET MANAGEMENTDigital asset management (DAM) consists of management tasks and decisions surroundingthe ingestion, annotation, cataloguing, storage, retrieval and distribution of digital assets.Digital photographs, animations, videos and music exemplify the target areas of media assetmanagement (a sub-category of DAM).Digital asset management systems (DAMS) include computer software and hardwaresystems that aid in the process of digital asset management.The term "digital asset management" (DAM) also refers to the protocol for downloading,renaming, backing up, rating, grouping, archiving, optimizing, maintaining, thinning, andexporting files.The "media asset management" (MAM) sub-category of digital asset managementmainlyaddresses audio, video and other media content. The more recentconcept of
enterprise content management (ECM) often deals with solutions which address similarfeatures but in a wider range of industries or applications.