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Friday, March 22, 2013


This week we looked at image file formats including GIF (Graphics Interchange Format) which uses 8 bits per pixel. It has at most 256 colors and it's compression is lossless and is ldeal for logos and graphics.

        We also looked at run length encoding which replaces multiple occurences of an item by stating the number of times that item appears. Turning an image on its side 90 degrees can either make run length encoding more or less usable therefore changing the file size of the image drastically.
        Progressive downloading was mentioned which gave the user a blurred preview image of the image they were downloading. This is not of much use anymore as everyone has high speed broadband and instantaneous downloads and could only come in handy on a mobile website.
       JPEG (Joint Photographs Experts Group) was created to make a standardised digital file format in which the degree of compression can be adjusted. It is the most common image file format on the web and is ideal for landscape images or any that don't use run length encoding.

       We also talked about luminence and chromanence, the brightness and color information in an image. Humans aren't great detecting changes in chromanence so files can be compressed by throwing away lots of the chromanence information whereas luminence information is very noticable to the human eye and can't be compressed too much without degrading the quality of the picture to anyone viewing it.

Thursday, March 14, 2013

Week 7

This week we talked about image compression. The differences between lossy and lossless compression was explained. Compression ratio vs quality was covered, which will be a large part of our assingment 2.This will involve a report on the trade-off between size and quality in JPEG and GIF images.

We talked about how to effectively reduce the number of colors in an image to a significant degree without having it look blocky. This can be done by either using the closest color available to the deleted one in our reduced palet,( color look up table). Dithering is also useful in that it prevents banding of colors.

Thursday, March 7, 2013

Week 6

This week in class we discussed search engine optimisation. Basically how to best use a search engine to better find your website. Without using shortcuts which in the long term will get you in a search engine's bad books and end up costing you. Search engines only search text, images and any layout such as logos and diagrams other than text are ignored.
                     Using keywords seems to be the best way to use search engine optimisation as long as the keywords are relevant to your site. This should be done for each page of the site not just the home page. Abbreviations are also best avoided as this can represent several things across the world.