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ECSE-6640 Digital Picture Processing Prof. George Nagy (nagy@ecse.rpi) Image and Document Formats & Conversion PowerPoint Presentation
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ECSE-6640 Digital Picture Processing Prof. George Nagy (nagy@ecse.rpi.edu) Image and Document Formats & Conversion Tong Zhang ( zhant@rpi.edu ) Coverage Image representations with different formats ( meta-information ) GIF, BMP, JPEG, TIFF, PBM, PGM, PPM, PS, EPS

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ECSE-6640 Digital Picture ProcessingProf. George Nagy (nagy@ecse.rpi.edu)Image and Document Formats & Conversion

Tong Zhang (zhant@rpi.edu)

coverage
Coverage
  • Image representations with different formats (meta-information) GIF, BMP, JPEG, TIFF, PBM, PGM, PPM, PS, EPS
  • Document representations that combine images, texts, music, video etc.

Latex, SGML, XML, HTML, PDF (Portable Document Format), ODA (Office Document Architecture)

outline
Outline
  • Why discuss this topic?
  • What are the categories?
  • What are the common types of image formats?
  • What are the tools to view and manipulate them?
  • Which one should I pick to use?
  • How to guess an image format?
  • Document formats
1 why discuss this topic
1. Why discuss this topic?
  • Understand the advantages and disadvantages of various image formats
  • Know the available tools
  • Aware of what’s going on when using these tools
  • Choose the appropriate image format for your own work
2 what are the categories
2. What are the categories?

One categorization:

  • Raster Image Formats
  • Vector Image Formats

Another categorization:

  • Binary Image Formats
  • ASCII Image Formats
2 1 raster image formats
2.1 Raster Image Formats
  • Breaks the image into a series of color dots called “pixels”
  • The number of bits at each pixel determines the maximum number of colors

1 bits = 2 (21) colors

2 bits = 4 (22) colors

4 bits = 16 (24) colors

8 bits = 256 (28) colors

16 bits = 65,536 (216) colors

24 bits = 16,777,216 (224) colors!

2 2 vector image formats
2.2 Vector Image Formats
  • Break the image into a set of mathematical descriptions of shapes: curve, arc, rectangle, sphere etc.
  • Resolution-independent: scalable without the problem of “pixelating”.
  • Not all images are easily described in a mathematical form. How to describe a photograph?
2 3 comparison
Raster

Resolution-dependent

Suitable for photographs

Smooth tones and subtle details

Larger size

Vector

Resolution-independent

Suitable for line drawings, CAD, logos

Smooth curves

Smaller size

2.3 Comparison
3 what are the common types of image formats
3. What are the common types of image formats?
  • Raster: GIF (Graphics Interchange Format), Bitmap,JPEG, TIFF, PBM (Portable Bit Map - binary), PGM (Portable Gray Map – grayscale), PPM(Portable Pixel Map - color), PNM (Portable Any Map – any three), PCD(Photo CD), PNG (Portable Network Graphics), etc.
  • Vector: PS(Postscript), EPS (Embedded Postscript), CDW (CorelDraw), WMF (Windows Metafile), SVG (Scalable Vector Graphics), etc.
3 1 compuserv gif graphics interchange format
3.1 CompuServ GIF – Graphics Interchange Format
  • First standardized in 1987 by CompuServ (called GIF87a)
  • Updated in 1989 to include transparacy, interlacing, and animation (called GIF89a)
  • Use the LZW (Lempel-Ziv Welch) algorithm for compression
  • A maximum of 256 colors, so doesn’t work well for photographs
  • Suitable for small images such as icons
  • Simple animations
  • Interlacing vs. non-interlacing
3 2 bitmaps
3.2 Bitmaps
  • Can create great image with 24 or even 32 bits per pixel
  • File size is large, for example, a bitmap image of size 1024x768 with 24 bits per pixel is at least 1024x768x3 = 2 MBs
  • How to reduce size? Run Length Encoding (RLE) – lossless
  • What about even smaller size? Lossy encoding such as JPEG.
3 3 jpeg joint photographic experts group
3.3 JPEG (Joint Photographic Experts Group)
  • Lossy encoding
  • Like interlaced GIFs, there is progressive JPEGs
3 4 tiff tag image file format
3.4 TIFF (Tag Image File Format)
  • Tag-based image format
  • Originated in 1986 at Aldus Corp. (PageMaker), the latest version 6.0
  • Developed by Aldus and Microsoft
  • Platform-independent
  • Mostly used by scanners and desktop publishing
  • http://www.libtiff.org/ for a TIFF library
  • Support compressions of CCITT Fax 3 & 4, LZW, JPEG etc.
  • Support multiple color spaces: Grayscale, RGB, YCbCr, CMYK etc.
some details
File Header

Byte Order (2 bytes): MM or II

Version (2 bytes): 42 (deep philosophical reason!)

Pointer to first IFD (4 bytes)

IFD (Image File Directory)

Pointer count (2 bytes)

Tagged Pointer 0 (12 bytes)

Tagged Pointer 1 (12 bytes)

….

Pointer to next IFD (if none, 0000) (4 bytes)

Some details
some details continued
Some details - continued
  • Tagged pointer (12 bytes)
  • Tag code (2 bytes): in the specs
  • Type of data (2 bytes): 1 (BYTE), 2 (ASCII), 3 (SHORT), 4 (LONG), 5 (rational)
  • Length (4 bytes)
  • Data pointer or data field
3 5 pbm pgm ppm portable bit map portable gray map portable pixel map
3.5 PBM, PGM, PPM (Portable Bit Map, Portable Gray Map, Portable Pixel Map)
  • ASCII / Binary format
  • Easy to edit

a.pbm a.pgm a.ppm

P1/P4

P2/P5

P3/P6

3 6 ps postscript
3.6 PS (PostScript)
  • A programming language from Adobe for printing graphics and text (stack based, interpreted language using RPN – Reverse Polish Notation)
  • A page description language that is device-independent (introduced in 1985 by Adobe)
  • Different levels: Level 1, 2, 3
  • Change coordinate system, scaling, translation, rotation, filling, clipping, etc.
  • Main unit: point (1/72 of an inch)
3 7 eps embedded postscript
3.7 EPS (Embedded PostScript)
  • A Postscript with additional rules
  • For putting postscript in a document
  • Essential information: what is the size of the image
3 8 svg scalable vector graphics
3.8 SVG (Scalable Vector Graphics)
  • A language for describing 2D graphics and applications in XML
  • SVG specification and current implementations: http://www.w3.org/TR/SVG/
  • Adobe SVG Viewer http://www.adobe.com/svg/main.html
4 what are the tools to view and manipulate them
4. What are the tools to view and manipulate them?
  • Use image editors
  • For raster image: Abobe Photoshop, Paint Shop Pro, xv
  • For vector image:Adobe Freehand, Adobe Illustrator, ghostview, xfig
  • For conversion between different image formats: ImageMagick (free with different platforms)
5 which one should i use
5. Which one should I use?
  • No unique answer
  • A small image like icons, a grayscale image – GIF
  • A large image, photographs, an image with many colors – JPEG
  • Scalability required – PS, EPS
6 how to guess an image format
6. How to guess an image format?
  • Image magic words

GIF: “GIF”

TIFF: “II” or “MM”

BMP: “BMP”

JPEG: FF,D8 (hexadecimal) – Start of Image Marker (SOI)

PS: %!PS-Adobe-3.0

EPS: %!PS-Adobe-3.0 EPSF-3.0

7 document representations
7. Document Representations
  • Text: ASCII, UNICODE
  • Page composition languages- Word processing (WYSIWYG), RTF- Typesetting (Tex, FrameMaker)
  • Document Interchange Formats: DIF(Document Interchange Format), SGML, ODA (Office Document Architecture)
  • Presentation Formats: HTML, PDF
7 1 tex latex
7.1 Tex & LaTeX
  • A high-quality typesetting system
  • Designed to produce technical and scientific documentation
  • Based on Donald E. Knuth's TeX typesetting language
  • First developed in 1985 by Leslie Lamport
  • Cross-platform
  • Useful if you are writing your thesis!
7 2 dif document interchange format
7.2 DIF (Document Interchange Format)
  • Text only, no graphics or complex structures
  • ASCII stream of text and instructions (prefixed by ESC)
7 3 office document architecture oda
7.3 Office Document Architecture (ODA)
  • A market code standard by ISO
  • For actual coding, it has a companion called Office Document Interchange Format (ODIF)
  • Describes the logical structure and layouts.
7 4 standard generalized markup language sgml
7.4 Standard Generalized Markup Language (SGML)
  • “Meta” language: used to define markup languages
  • Established by the International Standards Organization (ISO) in 1986
  • SGML is not a markup standard, but a framework for devising such a standard
  • http://xml.coverpages.org/sgml.html
7 5 hypertext markup language html
7.5 Hypertext Markup Language (HTML)
  • A subset of SGML (an application of SGML)
  • A HTML file is in ASCII
  • Has standard codes
  • Can be edited by a simple text editor, but dedicated authoring tools are usually much more convenient
7 6 portable document format pdf
7.6 Portable Document Format (PDF)
  • Adobe’s de facto standard for secure and reliable distribution and exchange of electronic documents
  • Can embed fonts, images, graphics, forms, controls, layouts, media, etc.
  • Searchable, hyperlinks, digital signature,
  • Application and platform independent
  • http://partners.adobe.com/asn/tech/pdf/index.jsp
7 7 rtf rich text format
7.7 RTF (Rich Text Format)
  • Microsoft
  • Text & graphics
  • Use ANSI, PC-8, Macintosh, or IBM PC character sets
  • Currently the documents can be transferred between Windows and Macs