ECSE-6640 Digital Picture Processing
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ECSE-6640 Digital Picture Processing Prof. George Nagy ([email protected]) Image and Document Formats & Conversion Tong Zhang ( [email protected] ) Coverage Image representations with different formats ( meta-information ) GIF, BMP, JPEG, TIFF, PBM, PGM, PPM, PS, EPS

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Slide1 l.jpg

ECSE-6640 Digital Picture ProcessingProf. George Nagy ([email protected])Image and Document Formats & Conversion

Tong Zhang ([email protected])

Coverage l.jpg

  • 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 l.jpg

  • 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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg



Suitable for photographs

Smooth tones and subtle details

Larger size



Suitable for line drawings, CAD, logos

Smooth curves

Smaller size

2.3 Comparison

3 what are the common types of image formats l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
3.3 JPEG (Joint Photographic Experts Group)

  • Lossy encoding

  • Like interlaced GIFs, there is progressive JPEGs

3 4 tiff tag image file format l.jpg
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

  • 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 l.jpg

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 l.jpg
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 l.jpg
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




3 6 ps postscript l.jpg
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 l.jpg
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 l.jpg
3.8 SVG (Scalable Vector Graphics)

  • A language for describing 2D graphics and applications in XML

  • SVG specification and current implementations:

  • Adobe SVG Viewer

4 what are the tools to view and manipulate them l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
7. Document Representations


  • 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 l.jpg
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 l.jpg
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 l.jpg
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 l.jpg
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


7 5 hypertext markup language html l.jpg
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 l.jpg
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


7 7 rtf rich text format l.jpg
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