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Thread: Character limit on alt-text in PDF?

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Number of posts in this thread: 7 (In chronological order)

From: McMorland, Gabriel
Date: Fri, Jun 28 2013 12:43PM
Subject: Character limit on alt-text in PDF?
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Is there a character limit on the alt-text for images in PDFs?
If not, then how long is too long?

Also, where do you usually put long descriptions for complex images in PDFs hosted on a website? If it was HTML I could use longdesc, but I'm not sure where to put them with the PDFs used in our online courses.

Thanks for your thoughts,
Gabe

From: Olaf Drümmer
Date: Fri, Jun 28 2013 2:03PM
Subject: Re: Character limit on alt-text in PDF?
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Hi Gabe,

there is no strict limit. Some will assume that having an alt text longer than 32 kilobytes (32767 bytes) might not be a good idea.

What kind of limit are you running into? Why would you have to have a very long description to begin with?


Olaf


On 28 Jun 2013, at 20:43, McMorland, Gabriel wrote:

> Is there a character limit on the alt-text for images in PDFs?
> If not, then how long is too long?
>
> Also, where do you usually put long descriptions for complex images in PDFs hosted on a website? If it was HTML I could use longdesc, but I'm not sure where to put them with the PDFs used in our online courses.
>
> Thanks for your thoughts,
> Gabe
> > >

From: Chagnon | PubCom
Date: Fri, Jun 28 2013 2:03PM
Subject: Re: Character limit on alt-text in PDF?
← Previous message | Next message →

RE: Alt-text length. I was advised long about to keep it under 200
characters. Can't even begin to find where that recommendation came from.

RE: long descriptions in PDFs, this question has been asked a few times on
this list and never, in my opinion, satisfactorily answered.

WCAG doesn't acknowledge that PDFs exist. <grin>

We've developed some solutions that we think meet the intent of WCAG 2.0,
based on what WAI technique 1.1.1 recommends for websites
http://www.w3.org/WAI/WCAG20/quickref/#qr-text-equiv-all

1) For graphical charts and other graphics that illustrate statistical data:

- If the source document is available, add a table below the graphical chart
that contains the same data. We've found that our AT testers prefer this
solution because it gives them direct access to the data.

- If you can't change the source document but are stuck working with just
the PDF, add a blank page at the end of the PDF and put the table there. In
some cases, it can be helpful to also have a paragraph of text to describe
or analyze the data, what a LONGDESC would do. Hyperlink from the graphic to
the back page, and then hyperlink a return to the original page. Messy to
create, but it works fine for AT-users.

2) For other situations:

- If you can edit the original source document, work a narrative description
into the body text that describes the graphic's data. Something like "in the
bar chart below, sales increased to $2,000 in May, a 100% increase from
April which were $1,000."

- If you can't, the "back of the PDF" method above will work for this, too.

-Bevi Chagnon
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
www.PubCom.com - Trainers, Consultants, Designers, Developers.
Print, Web, Acrobat, XML, eBooks, and U.S. Federal Section 508
Accessibility.
New Sec. 508 Workshop & EPUBs Tour in 2013 - www.Workshop.Pubcom.com

-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of McMorland,
Gabriel
Sent: Friday, June 28, 2013 2:43 PM
To: = EMAIL ADDRESS REMOVED =
Subject: [WebAIM] Character limit on alt-text in PDF?

Is there a character limit on the alt-text for images in PDFs?
If not, then how long is too long?

Also, where do you usually put long descriptions for complex images in PDFs
hosted on a website? If it was HTML I could use longdesc, but I'm not sure
where to put them with the PDFs used in our online courses.

Thanks for your thoughts,
Gabe
messages to = EMAIL ADDRESS REMOVED =

From: McMorland, Gabriel
Date: Mon, Jul 01 2013 8:23AM
Subject: Re: Character limit on alt-text in PDF?
← Previous message | Next message →

Thanks, *I hadn't thought of that back of the PDF technique. It will probably help with maintenance because all the content will be contained in one document.

-----Original Message-----
From: = EMAIL ADDRESS REMOVED = [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Chagnon | PubCom
Sent: Friday, June 28, 2013 4:04 PM
To: 'WebAIM Discussion List'
Subject: Re: [WebAIM] Character limit on alt-text in PDF?

RE: Alt-text length. I was advised long about to keep it under 200 characters. Can't even begin to find where that recommendation came from.

RE: long descriptions in PDFs, this question has been asked a few times on this list and never, in my opinion, satisfactorily answered.

WCAG doesn't acknowledge that PDFs exist. <grin>

We've developed some solutions that we think meet the intent of WCAG 2.0, based on what WAI technique 1.1.1 recommends for websites http://www.w3.org/WAI/WCAG20/quickref/#qr-text-equiv-all

1) For graphical charts and other graphics that illustrate statistical data:

- If the source document is available, add a table below the graphical chart that contains the same data. We've found that our AT testers prefer this solution because it gives them direct access to the data.

- If you can't change the source document but are stuck working with just the PDF, add a blank page at the end of the PDF and put the table there. In some cases, it can be helpful to also have a paragraph of text to describe or analyze the data, what a LONGDESC would do. Hyperlink from the graphic to the back page, and then hyperlink a return to the original page. Messy to create, but it works fine for AT-users.

2) For other situations:

- If you can edit the original source document, work a narrative description into the body text that describes the graphic's data. Something like "in the bar chart below, sales increased to $2,000 in May, a 100% increase from April which were $1,000."

- If you can't, the "back of the PDF" method above will work for this, too.

-Bevi Chagnon
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - - - -
www.PubCom.com - Trainers, Consultants, Designers, Developers.
Print, Web, Acrobat, XML, eBooks, and U.S. Federal Section 508 Accessibility.
New Sec. 508 Workshop & EPUBs Tour in 2013 - www.Workshop.Pubcom.com

-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of McMorland, Gabriel
Sent: Friday, June 28, 2013 2:43 PM
To: = EMAIL ADDRESS REMOVED =
Subject: [WebAIM] Character limit on alt-text in PDF?

Is there a character limit on the alt-text for images in PDFs?
If not, then how long is too long?

Also, where do you usually put long descriptions for complex images in PDFs hosted on a website? If it was HTML I could use longdesc, but I'm not sure where to put them with the PDFs used in our online courses.

Thanks for your thoughts,
Gabe

From: McMorland, Gabriel
Date: Mon, Jul 01 2013 8:28AM
Subject: Re: Character limit on alt-text in PDF?
← Previous message | Next message →

We sometimes need long descriptions to describe complex diagrams, flowcharts, or maps.

I'm not running into a technical character limit, but I'm interested in design choices others have made.

-----Original Message-----
From: = EMAIL ADDRESS REMOVED = [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Olaf Drümmer
Sent: Friday, June 28, 2013 4:03 PM
To: WebAIM Discussion List
Subject: Re: [WebAIM] Character limit on alt-text in PDF?

Hi Gabe,

there is no strict limit. Some will assume that having an alt text longer than 32 kilobytes (32767 bytes) might not be a good idea.

What kind of limit are you running into? Why would you have to have a very long description to begin with?


Olaf


On 28 Jun 2013, at 20:43, McMorland, Gabriel wrote:

> Is there a character limit on the alt-text for images in PDFs?
> If not, then how long is too long?
>
> Also, where do you usually put long descriptions for complex images in PDFs hosted on a website? If it was HTML I could use longdesc, but I'm not sure where to put them with the PDFs used in our online courses.
>
> Thanks for your thoughts,
> Gabe
> > > list messages to = EMAIL ADDRESS REMOVED =

From: Olaf Drümmer
Date: Mon, Jul 01 2013 9:08AM
Subject: Re: Character limit on alt-text in PDF?
← Previous message | Next message →

Based on observations made in a number of seminars on accessible PDFs I have done in the last months it became very clear to me that getting accessibility right is cheapest when as much as possible can be done on the editorial level (whether that's for online content or PDFs). A good strategy is always: if you have content that would be presented with lots of visuals but without text just add the respective text somewhere else. As long as content is distributed electronically there is always enough space!

For example - if you have some business graphics, just grab that Excel spreadsheet, and insert it as a table next to the business graphic (or if that's not an option, in the appendix); then point to it (or in the case of the annex, link to it), and all you need to add as alternate text/description is a pointer to the text based version of the data.


Olaf


On 1 Jul 2013, at 16:28, McMorland, Gabriel wrote:

> We sometimes need long descriptions to describe complex diagrams, flowcharts, or maps.
>
> I'm not running into a technical character limit, but I'm interested in design choices others have made.
>
> -----Original Message-----
> From: = EMAIL ADDRESS REMOVED = [mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Olaf Drümmer
> Sent: Friday, June 28, 2013 4:03 PM
> To: WebAIM Discussion List
> Subject: Re: [WebAIM] Character limit on alt-text in PDF?
>
> Hi Gabe,
>
> there is no strict limit. Some will assume that having an alt text longer than 32 kilobytes (32767 bytes) might not be a good idea.
>
> What kind of limit are you running into? Why would you have to have a very long description to begin with?
>
>
> Olaf
>
>
> On 28 Jun 2013, at 20:43, McMorland, Gabriel wrote:
>
>> Is there a character limit on the alt-text for images in PDFs?
>> If not, then how long is too long?
>>
>> Also, where do you usually put long descriptions for complex images in PDFs hosted on a website? If it was HTML I could use longdesc, but I'm not sure where to put them with the PDFs used in our online courses.
>>
>> Thanks for your thoughts,
>> Gabe
>> >> >> list messages to = EMAIL ADDRESS REMOVED =
>
> > > > >

From: Chagnon | PubCom
Date: Mon, Jul 01 2013 9:24AM
Subject: Re: Character limit on alt-text in PDF?
← Previous message | No next message

Great, simple summary, Olaf.

One question: As far as I know, we can't yet put hyperlinks in Alt-text and
I haven't checked that particular issue lately. Has anything changed that
allows us to do that?

—Bevi Chagnon
- - -
www.PubCom.com — Trainers, Consultants, Designers, Developers.
Print, Web, Acrobat, XML, eBooks, and U.S. Federal Section 508
Accessibility.
New Sec. 508 Workshop & EPUBs Tour in 2013 — www.Workshop.Pubcom.com

-----Original Message-----
From: = EMAIL ADDRESS REMOVED =
[mailto: = EMAIL ADDRESS REMOVED = ] On Behalf Of Olaf Drümmer

Based on observations made in a number of seminars on accessible PDFs I have
done in the last months it became very clear to me that getting
accessibility right is cheapest when as much as possible can be done on the
editorial level (whether that's for online content or PDFs). A good strategy
is always: if you have content that would be presented with lots of visuals
but without text just add the respective text somewhere else. As long as
content is distributed electronically there is always enough space!

For example - if you have some business graphics, just grab that Excel
spreadsheet, and insert it as a table next to the business graphic (or if
that's not an option, in the appendix); then point to it (or in the case of
the annex, link to it), and all you need to add as alternate
text/description is a pointer to the text based version of the data.

Olaf