Hello, and welcome to Mouse Not Found, your genial guide to
the cyber-world of the Internet!
One of the things I like to talk about is our club website,
located at http://www.vantasia.org, and
why not! We’ve been live on the Internet for about two years now, and during
that time we’ve been visited more than 16000 times by people from all around the
world, and all walks of life. During that time our site has evolved into one of
the premier sites on Turkish Van cats in the world, has drawn new members into
the club, and has found new homes for many of our rescue cats. It’s been a real
asset to the club, and also to club members who are able to advertise kittens
for sale, or just show off their pets in the photo
gallery.
One of the things that confuses many Internet users is how
best to email pictures. I’ve had several messages that take many minutes to
receive because they contain an attachment, usually a picture. This can be
annoying at best for email recipients, and is critical when considering pictures
on a web site since viewers are unlikely to wait for 10 minutes while a web page
loads on their browser. So lets talk a little about picture formats!
There are many file formats for storing pictures on a
computer, but over the Internet we mainly confine ourselves to two formats:- GIF
files (correctly pronounced with a soft G) and JPEG files (pronounced jay-peg).
Both formats can be used for storing pictures, but the choice of which one
depends upon the content of the pictures. Let me explain! The main issue here is
how to store as much information about your picture as possible in the smallest
amount of disk space, and to achieve this we use various forms of compression.
If we imagine a row of 50 blue pixels (a pixel is a best thought of as single
dot on your screen) we could replace this with one pixel followed by a code that
tells the computer to repeat this pixel another 49 times. This would be really
great for pictures containing large areas of blue (or any other colour of
course), but not so good for photographs where adjacent pixels are likely to
have different shades. Alternatively we can use a clever algorithm that looks at
groups of pixels and fits them to a mathematical pattern that approximately
describes the difference between the pixels in the group. This strongly favours
photographs, and the loss in quality due to the small approximations made is
generally not visible except in extreme cases.
Another consideration is colour depth, i.e. how many bits of
data are used to store the colour of each pixel. The more we use, the more
colours we can represent, but the bigger the file size! Photographs usually
contain many different shades & hues, so a greater colour-depth is preferred,
whereas a black-and-white line drawing only needs two colours.
Coming back to GIF and JPEG then, GIF uses 8 bits to represent
each pixel’s colour, whilst JPEG uses 24, so JPEG would be better for
photographs whilst GIF is best used where the total number of colours is small,
i.e. less than 256. If we also consider the compression algorithms, GIF uses the
“repeat the last pixel so many times” approach, whilst JPEG uses that
mathematical algorithm. So again, JPEG favours photographs and GIF favours
pictures with solid colour (e.g. cartoons).
There’s one more factor that may influence your choice of
picture format, and that’s transparency. In GIF files we can set one of the
colours to be a transparent colour, i.e. the background shows through. This is
like painting a picture on a sheet of glass then holding it up so that you can
see through the bits without paint, and is very useful on websites where you
want the picture to be superimposed on a background. JPEG files don’t have this
capability.
Well lets see an example! When you next visit our club site at
http://www.vantasia.orghave a look at the pictures on the main page. If you use Internet
Explorer as your browser then place the mouse over the picture of Foxy (the
Turkish Van) and click the right-hand mouse button. A menu will pop up and the
bottom item is labelled “Properties”, so click on this. You will now see the
properties of the picture, and see that it is a file called foxy_cover2.jpg,
i.e. a JPEG picture! Now do the same for the club logo in the top left corner
and you’ll see it’s a file named ctvca_t.gif, a GIF file! For this one we also
make use of the transparency capabilities, which is why the orange background
shows through. Netscape users can see this information all in one window by
right-clicking on the page and selecting the “View Info” menu item.
One final comment – most home computer users have their screen
set to a resolution of 800 pixels across by 600 down, or maybe more, which means
that a picture with dimensions no larger than 600 by 400 can be easily viewed in
its entirety without having to be scrolled around. There’s no point in making
pictures any bigger unless they’re intended for printing, and smaller pictures
take less time to download too!
I’ll leave you now with a few links for you to explore. The
first one is a repository of cat related quotes, proverbs, and poems etc, and
also has pictures of various famous cartoon cats. Cat Quotes can be found at
http://www.catquotes.com.
Cats have appeared in many films, books, and games over the
years, and you can find out about many of them at
http://www.citizenlunchbox.com/famous/cats.html. Do you know who holds the
record for the most mice killed (about 22,000)?
