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Thread: Characters in Alt attribute

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From: Mamta Tandel
Date: Wed, Aug 17 2005 8:00AM
Subject: Characters in Alt attribute
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Hi all,



Does anyone know the maximum length of characters to be specific in alt
attribute? In addition, what number of characters do you suggest should be
ideal keeping accessibility and usability in mind?



Are there any guidelines specifying the number of characters considered
ideal for alt attribute?



Regards,

Mamta




From: Christian Heilmann
Date: Wed, Aug 17 2005 8:20AM
Subject: Re: Characters in Alt attribute
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> Does anyone know the maximum length of characters to be specific in alt
> attribute? In addition, what number of characters do you suggest should be
> ideal keeping accessibility and usability in mind?
> Are there any guidelines specifying the number of characters considered
> ideal for alt attribute?

Quoting Joe Clark
http://www.joeclark.org/book/sashay/serialization/Chapter06.html :

Keep the alt text short. There is no set limit on the length of an alt
text, but as we shall see shortly, a very long alt may not be fully
displayed when image-loading is turned off or when the browser cannot
locate the image file. By convention, limit alt texts to 1,024
characters (1 K) or less.

When it comes to writing the actual text, remember that alt takes the
place of the graphic. Tell us what the picture is or represents or sum
up its function, but don't tell us that it's a picture. I'll give you
actual examples in a moment, but steer clear of writing a sort of
metaalt text, like "Picture of sunset over Darling Harbour" or
"Picture of company logo."

endquote

Read on how you can add more information via title or if needed via longdesc.

The alt is the image replacement, no need to tell stories, unless your
image is a story, then image replacement might be the better idea
anyway.



From: Jukka K. Korpela
Date: Wed, Aug 17 2005 3:20PM
Subject: Re: Characters in Alt attribute
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On Wed, 17 Aug 2005, Mamta Tandel wrote:

> Does anyone know the maximum length of characters to be specific in alt
> attribute?

There is no theoretical maximum, but 50 characters is a useful practical
limit. Exceed it only if the benefits to users using advanced browsers
like Lynx (which has no problems with long alt texts) outweigh the
problems of people who use IE in a mode where images are not displayed.

> In addition, what number of characters do you suggest should be
> ideal keeping accessibility and usability in mind?

As many as necessary, but not more.

In practice, most alt texts can be written much shorter than 50
characters, whereas some content-rich images really correspond to a
thousand words. There's little point in putting those thousand words into
an alt attribute (which is plain text and cannot even contain paragraph
breaks!). Instead, put the words elsewhere and link to them suitably.
This often lets you use an empty alt text (since alternate content is
offered via the link) or a purely labelling alt text.

--
Jukka "Yucca" Korpela, http://www.cs.tut.fi/~jkorpela/