1. GRAPHICAL DATA
EXCHANGE FORMATS
.jpg
.gif
.tif

2. Graphics Interchange Format (.GIF)
Byte Image Data Stored
in Row Major Order

3. Contains RGB Values for
Graphics Interchange Format (.GIF)
768 Byte Indexed Color Table
Contains RGB Values for
256 Colors or Gray Tones

4. Graphics Interchange Format (.GIF)
Lempel, Ziv, Welch (LZW) image
Compression Used on all Images
Looks for and Codes Repeated
Pixel Patterns in the Image
Works Best for
Large Areas of
the Same Color

5. Pixel Density is Important
Choosing the Correct
Pixel Density is Important
for Maintaining Image Quality

6. Joint Photographic Experts Group (.JPG)
File Format
One or Three-Byte
Image Data Stored
in Row Major Order

7. Joint Photographic Experts Group (.JPG) Data are Compressed using a
File Format
Data are Compressed using a
“Lossy" Method where
Some Data are Lost

8. Joint Photographic Experts Group (.JPG)
File Format
Data are Compressed
using a "Lossy" Method
where some Data
are Lost
User Specifies the
Level of Image
Quality from Best (10)
to Worst (1)

9. Joint Photographic Experts Group (.JPG)
File Format
Image Quality Generally
Good at Higher
Levels of Compression
Better Compression Scheme
for Photomaps and
Relief Shading
than .GIF

10. Tagged Image
File Format
(.tif or .tiff)

11. TIFF Advantages Flexible and adaptable file format.
Can have multiple images and data in a single file through the inclusion of "tags" in the file header.
Tags indicate the basic geometry of the image, such as its size, or if one of several image compression options are used.

12. TIFF World
File --GEOTIFF
(.tfw)

13. ESRI TIFF World File – 6 ASCII Lines
Horizontal distance in meters represented by each pixel.
Rotation angle about the y axis.
Rotation angle about the x axis.
Vertical distance in meters represented by each pixel. Normally negative because an image has its origin in the top left corner.
Easting coord. of the center of the top left pixel.
Northing coord. of the center of the top left pixel.

14. TFW File Example
0.6
-0.6
Sometimes will have two additional lines:
Grid zone or coordinate system
Datum