B.Digital graphics. Color Models. Image Data. RGB (the additive color model) CYMK (the subtractive color model)

Transcription

1 Image Data Color Models RGB (the additive color model) CYMK (the subtractive color model)

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3 Pixel Data Color Depth Every pixel is assigned to one specific color. The amount of data stored for every pixel, decides how many color possibilities it can afford. This amount is given by : bit per pixel (bpp) The (RGB) model acquires one byte (8 bits) of data for each of the three colors for every pixel. That's 24 bpp (bit per pixel) (known as True Color)

4 Color Depth 1 bpp (a single bit per pixel)

5 Color Depth 4 bpp (half a byte per pixel)

6 Color Depth 8 bpp (one byte per pixel)

7 Color Depth 16 bpp (two bytes per pixel)

8 Color Depth 24 bpp (True Color: 3 bytes per pixel)

9 Pixel Data Allowing 24 bits per pixel gives 256 levels for each component and over 16 million different colours - more than the human eye can distinguish However, many color display systems use only one byte (limiting the display to 256 different colors). Certain raster formats support 32 bpp with further data for alpha channels Alpha channels are data (algorithms) specified for transparency and opacity properties in digital images)

10 Pixel Data: Pixel data include many classes of information that vary according to the specific format used for the image. such data, in addition to Pixel color, may include: alpha channels (pixel transparency level), gamma corrections (pixel brightness level), pixel compression code (if supported). Etc. Some raster formats also support little loop animation data.

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15 Image data Format: It is the programming g pattern & set of algorithms, that define the way the data compose the image, the way they are distributed, classified, the visual abilities they give to the image, and the way they deal with related hard ware items.

16 Raster Image Data Raster image data: Any digital image file that is composed mainly of Pixels in the form of a Bitmap is known as a Raster image. Raster Formats: all image formats built on raster image programming, are known as raster formats. They vary according to the type of Pixel data they support.

17 Raster Image Data Tagging: is the ability to store text data within an image file. Like writing info on the back of a photo, tagging data could include anything from technical details, copyright information, keywords, dates, full description and details. A file name and resolution, and file size, are most common tags associated with raster files

18 Raster Image Data Compression: The reduction of memory space a file occupies on a hard drive. Compression codes and protocols were invented for the following purposes: to maintain i high h image qualities within reasonable file sizes facilitate image data transfer process form the computer to the printing terminal enable high quality image publishing in web graphics

19 Raster Graphics Compression is either Lossy: a partial loss in image data takes place. so once an image is compressed in lossy compression, it can t be decompressed this type is better for web publishing. Lossless: no loss in image data takes place. this type is ideal for print publishing

20 Raster Formats

21 Raster Formats Bmp Gif Jpeg PNG TIFF TGA

22 Raster Formats Bmp Gif Jpeg PNG TIFF TGA Standard windows bitmap Windows bitmap files are stored in a Deviceindependent bitmap (DIB) format, which allows Windows to display the bitmap on any type of display device, under any software application. The default filename extension of a Windows DIB file is Filename. BMP It may use compression, though it is rare to find a compressed.bmp file It is not capable of storing animation

23 Raster Formats Bmp Gif Jpeg PNG TIFF TGA Graphics Interchange Format filename. gif GIF are mostly limited to 256 color. Which limits their use. The GIF format is best for images with solid colors or areas of uniform color such as illustrations and logos The GIF format uses lossless compression It supports simple animations

24 Raster Formats Bmp Gif Jpeg PNG TIFF TGA Joint Photographic Experts Group filename. jpg Jpeg format supports 24 bpp images, so they can host photographic images jpg format uses compression, it is a standardized compression tool. It uses lossy compression algorithms. A trade-off between image quality and file size has to be made in jpeg compression

25 Raster Formats Bmp Gif Jpeg PNG TIFF TGA Portable Network Graphics filename. png PNG format was designed to replace GIF it supports more data than GIF: alpha channels, gamma corrections (brightness control) & two dimensional interlacing PNG compresses better than GIF

26 Raster Formats Bmp Gif Jpeg PNG TIFF TGA Tag Image File Format filename. tif Highly flexible and platform-independent format, with high hardware compatibility wide range of options for color and control TIFF allows advanced image tagging TIFF uses the LZW lossless compression, and supports other kinds of compression like Jpg and ZIP TIFF allows color resolution up to 48 TIFF allows color resolution up to 48 bits (a 16-bit field each for R, G, and B)

27 Raster Formats Bmp Gif Jpeg PNG TIFF TGA Targa Graphics Adaptor filename. tga TGA is a common format for storage of 24 bit images, it supports high-color (16 bpp), true color images (24, 32 bpp) it supports alpha channels, reasonable lossless compression and tags TGA files are RLE compressed which results in significantly small file sizes, but will give slower performance when handling the image than TIFF compression

28 Format: Designed for: Top choice for: Format selection chart BMP GIF, PNG Screen display under Windows GIF :Screen display, especially the Web PNG: a developed GIF format. Online publishing of illustrations, screen shots Jpeg/ Jpg Screen display, especially the Web, image compression (lossy). Online publishing of photographic images TGA Printing to post script printers. High resolution Printing of images TIFF TIF Printing to PostScript printers, high hardware compatibility scanners, reasonable lossless compression. High resolution printing of images. Most suitable for wide area images.

29 Vector Graphics vector Image data : This type of image data programming is based on defining digital Image in terms of objects rather than pixels ( object oriented programming ) vector shape algorithms: the data equations that define full properties of an object in a vector image file.

30 Vector Graphics p Object (shape) properties: p object properties p include, Geometric shape parameters, aspect ratio (ratio of width to height), color or textures fill for the object, the objects ratio to all the other objects in the file (relative size), and its relative location in the file. Advanced vector formats also support more complicated properties for every object, like gamma and alpha channel specifications

31 Vector Graphics vector formats deal only with predefined shapes: simple or compound geometry, which h means that it works best for simple illustrations, logos and simple graphical applications in general. The fact that makes vector graphics ideal for simple web design elements, as they also consume much smaller memory space than raster formats. But vector graphics are inefficient for more complicated graphics applications like, photo real production, image editing, collage, and digital painting.

32 Vector Graphics CAD systems CAD is short for Computer Aided Drafting for architecture. All CAD systems are based on vector programming. The programming nature of CAD graphics like ease of proportional rescaling and precision of object definition, make CAD systems perfect candidates for geometric precision drawing.

33 Vector Graphics CAD Package: A software package is a software application in addition to other requirements and contents like: plugins, library suit, and any hardware devices Most popular CAD packages: AutoCAD Microstation intellicad TurboCAD DesignCAD

34 Cross Media Graphics Production (Cross Platform)

35 Cross Platform Cross Platform: this is the term we give to digital it graphics production that is feasible for editing and featuring through different types of compu-graphic media Example for raster formats that support cross media platform interchange: TIFF ( platform Independant). Jpg and Gif are essential for multimedia applications.

36 Cross Platform for architectural graphics, cross platform management is essential for defining i the most suitable format for images that will go from being included in a print sheet, to images that are viewed in a data show, or that will be part of a multimedia presentation,, or that will be published on a web site etc.

37 Cross Platform Format Conversions Raster to Raster Raster to Vector Vector to Raster Vector to Vector

38 Cross Platform Raster to Raster In architectural graphics, an image might be stored in TIFF or TGA for printing, so in order to make that very same image suitable for a PowerPoint presentation, it is better to compress it into a JPG, if it is photo real, or to GIF if it is only an illustration with few, single tone color areas. Raster Converters

39 Cross Platform Vector to Raster An architect could create a logo or an illustration, or a colored dwg plan in a vector application, but for final grouping g and full layout production, he will have to rasterize his vector image.

40 Cross Platform Raster to Vector Bitmap Tracing: Tracing a bitmap is a process that turns every group of pixels similar in Properties into an objec that will be reformatted as a vector object This process defines a color threshold, that is the quantity of close tone colors that should be abbreviated to their average tone (hue, saturation and value). Vectorizers / Bitmap Tracers

41 Cross Platform Vector to Vector Architects would generally do this type of Transformation from a CAD application to a vector render software like CorelDraw

42 Cross Media Graphics Production B.Digital graphics