1. September 21, 19981 COMPUTER VISION 600.461 WEB PAGE IS UP !! http://www.cs.jhu.edu/~wolff/course600.461/index.html OR Simply go to computer science homepage and go to homepage for Lawrence Wolff and look for link.

2. September 21, 19982 HOMEWORK POLICY This year homework assignments for the most part will be ‘handed-in’ on the web. This requires at the least that: –You have a web homepage. –You add a link COMPUTER VISION 600.461 to your homepage that points to the appropriate homework assignment being handed in. –You require a password to access the link to your respective homework assignments.

3. September 21, 19983 HOMEWORK POLICY A page will be maintained (linked to course 600.461 homepage) with a list of grades cross-referenced against the last 4 digits of your Social Security #. The usual rules regarding university policy on cheating will be strictly enforced.

4. September 21, 19984 HOMEWORK ASSIGNMENT Due Wed. Sept. 23 This is a really easy first homework assignment that acquaints you with a popular and a really useful image display tool called ‘XV’ Works on popular ‘Command Line’ environments such as UNIX and on DECs and SGIs. If you don’t already have this you can ftp from ftp://ftp.cis.upenn.edu/pub/xv

5. September 21, 19985 HOMEWORK ASSIGNMENT Due Wed. Sept. 23 Access image files desert.gif, peppers.gif and trees.gif displayed on Computer Vision course 600.461 homepage. Display the image trees.gif and enhance contrast using ‘gamma=3.0’ and ‘gamma=5.0’ intensity correction. Segment trees.gif into a binary image using respective grey level thresholds 50, 100 and 150. Display desert.gif and peppers.gif, respectively, and resave these images using jpeg achieving a 10:1 compression.

6. September 21, 19986 IMAGE FILE FORMATS BITMAP IMAGES VECTOR IMAGES (raster images) I(r,c) row column (r1,c1) (r2,c2) (r3,c3) While key points of a vector image are represented, this must ultimately be displayed as a bitmapped image called a rendering.

7. September 21, 19987 IMAGE FILE FORMATS Image files usually include the following information: Header –number of rows (height) –number of columns (width) –number of bands* –number of bits per pixel –file type (magic number) –type of compression * Image Data *optional but frequently used.

8. September 21, 19988 SOME COMMONLY USED IMAGE FORMATS BIN –raw data, no header –user must incorporate header information for applications. PPM –PBM (binary), PGM (gray-scale), PPM (color), PNM (handles all of the above) –headers consist of ‘magic number’ for file type, image width, image height, number of bands, and, maximum brightness which determines required number of bits/pixel

9. September 21, 19989 GIF IMAGE FORMAT GIF (Graphics Interchange Format) –Limited to 8 bits/pixel for both color and gray- scale. 0 R0 G0 B0 1 R1 G1 B1 8-bit index 2 R2 G2 B2 254 R254 G254 B254 255 R255 G255 B255 RED GREEN BLUE

10. September 21, 199810 TIFF IMAGE FORMAT TIFF (Tagged Image File Format) –More general than GIF –Allows 24 bits/pixel –Supports 5 types of image compression including: RLE (Run length encoding) LZW (Lempel-Ziv-Welch) JPEG (Joint Photographic Experts Group)

11. September 21, 199811 IMAGE COMPRESSION Compression Ratio –(Uncompressed File Size)/(Compressed File Size) Bits per Pixel –(Number of bits)/(Number of pixels)