Pictures on computers

Available free of charge from: http://www.adobe.com/svg/overview.html ... Of course these categories of software are overlapping. • Ideally 1 software package ...
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Pictures / images on computers Images are important

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Why learn the basics of images? Pictures/graphics/images are often inserted in » word processing documents » presentations with slides » web pages  Therefore, it is interesting to know how » to acquire images » to change or improve images » to adapt images to the chosen output medium

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Why learn the basics of images? • Scanning a document yields a picture, not a text. (OCR can then exploit the picture to yield a text in some cases.) • Pictures in a collection must be managed: »Storing »Making backups »Ordering / sorting images in a structure that can be browsed • This can be needed at a personal or institutional level, as a component of digital assets management.

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Why learn the basics of images? Documents are more and more made available through the Internet.  Therefore it is important to make the file sizes small, while preserving an appropriate image/picture quality.

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Pictures / images on computers Raster graphics versus vector graphics

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?? Question ??

Explain the differences between raster graphics and vector graphics.

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!! Task - Assignment !! •Create a small circle with a paint program for raster graphics and save this as a file.

•Create a small circle with a draw program for vector graphics and save this as a file. •Open each of both files again applying the same program that you used to create it and ENLARGE the circle.

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!! Task - Assignment !!

•What is the difference between the resulting drawings (on screen as well as printed)?

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Graphics formats: raster and vector graphics • Raster graphics used in programs for “painting”

• Vector-based graphics used in programs for “drawing”

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Graphics formats: raster & vector graphics compared

Property

Raster graphics Vector graphics

•Suited for “painting” and “retouching”

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•Resolution adapted to output medium

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large

small

•Size of files

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?? Question ??

In which procedures are vector-based graphics converted to raster graphics?

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?? Question ??

Why can raster graphics not be as easily converted to vector graphics, as vector graphics can be converted to raster graphics?

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?? Question ??

What is easier: Converting raster graphics to vector graphics or the other way? Explain.

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***-Examples

File formats for raster graphics only File name extension

Origin

.BMP .GIF .JPG .PCX, .PCC .PNG (PNG8, PNG24) .RLE .TIF ...

Microsoft bitmap CompuServe / Unisys JPEG Z-Soft Paintbrush W3C Microsoft compressed bitmap Aldus PageMaker ...

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**--Examples

File formats for vector graphics File name extension Name / Origin CDR CGM EPS SVG ...

Corel Draw! Graphics Metafile Encapsulated PostScript Scalable Vector Graphics ...

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!! Read !!

Read Scalable Vector Graphics. [online] Available free of charge from: http://www.adobe.com/svg/overview.html [cited 2005]

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Graphics formats: the problem of exchange The differences in all the graphics file formats cause the requirement of filter / conversion programs, when a graphics file must be inserted in a document which is managed by an application program which works primarily wi