3.4 Understand Images in Multimedia

Chapter 6-Images

3.4 UNDERSTAND IMAGES IN MULTIMEDIA

ObjectivesVarious factors that apply to the use of images in multimedia.Describe the capabilities and limitations of bitmap images.Describe the capabilities and limitations of vector images.Define various aspects of 3D modeling.Describe the use of colors and palettes in multimedia.Cite the various file types used in multimedia.

MULTIMEDIA IMAGESImages may be photograph-like bitmaps, vector-based drawings, or 3D renderings2D images are generated in two ways:Bitmaps (or raster-based) .Vector-drawn graphics.

BITMAPSBitmapderived from the words bit (simplest element in which only two digits are used)map, which is a two-dimensional matrix of these bits.A bitmap is a data matrix describing the individual dots of an image that are the smallest elements (pixels) of resolution on a computer screen or printer.Bitmaps are an image format suited for creation of:Photo-realistic images.Complex drawings.Images that require fine detail.

Bitmapped images can have varying bit and color depths.More bits provide more color depth, hence more photo-realism; but require more memory and processing powerColor is represented on a computer by using varying amounts of red, green and blue light.Monochrome just requires one bit per pixel

8 bits per pixel allows 256 distinct colors

Making Bitmaps Bigger

100%

500%

200%?Number of Colors = 2^(Bit-depth)

COLOR-DEPTH / BIT-DEPTH / COLOR RESOLUTIONBit depthColor resolutionCalcuation1-bit2 colors2^1 = 22-bit4 colors2^2 = 43-bit8 colors2^3 = 84-bit16 colors2^4 = 168-bits256 colors2^8 = 25616-bits65,536 colors2^16 = 6553624-bits16,777,215 colors2^24 = 16.7 million

VECTOR-DRAWN IMAGESVector-drawn images - created from geometric objects such as lines, rectangles, ovals, polygons using mathematical formulasVector-drawn images are used in the following areas:Computer-aided design (CAD) programs.Graphic artists designing for the print media.3-D animation programs.A vector is a line that is described by the location of its two endpoints.Vector drawing makes use of Cartesian co-ordinates.X, Y, and Z axis.XYZHOW VECTOR-DRAWN IMAGES WORKVector Image

100%

500%

200%VECTOR vs BITMAPS

3D graphics tools, such as Macromedia Extreme3D or Form-Z3 dimensions (x, y and z)The more elements, the finer the objects resolution and smoothness.Have properties such as shape, color, texture, shading & location.

3D DRAWING

FEATURES OF A 3-D APPLICATIONModeling involves drawing a shape, such as a 2D letter, then extruding it or lathing it into a third dimension.extruding : extends the shape of plane surface some distancelathing : rotating a profile of the shape around a defined axislighting, setting a camera view to project shadows

Rendering : produces a final output of a scene and is more compute-intensive.JPEG (Joint-Photographic Experts Group)For continuous tone images, such as full-color photographsMay lose informationGIF (Graphical Interchange Format)For large areas of the same color and a moderate level of detail.Allows transparency and interlacingUses lossless compressionPNG (Portable Network Graphic)lossless, portable, well-compressed storage of raster imagesMOST POPULAR IMAGE FILE FORMATSADVANTAGES OF USING IMAGEQuick way for the audience to visualize what you are sayingForceful -- emphasizes main pointConvincing -- proves a point, see and hearCompact way to convey informationMore interesting than just talk or print

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