[Blindmath] Extracting bitmap images from pdf files

Wed Jan 25 20:34:19 UTC 2012

It looks like the free online pdf to html converter at
http://www.pdftohtml.net/ will get the job done.

There are a couple of required steps that are probably not accessible by a
blind student, but at least if the student has a sighted assistant to
extract and crop the image files, the student can convert them to enhanced
sig files or enhanced  svg files and emboss them.

In case anyone is interested, I attached a zip file that contains two sig
files. Each sig file represents one half of an enhanced version of a bitmap
file extracted from a physics book. If you have access to an embosser that
will accept sig files as input, emboss each file and lay them side by side
to create the entire embossed image.

Parameters were set set for 8.5-inch page width at 12 dpi. If your embosser
has a different page width or dpi value, you should still get an output but
some of the output may not fit the page. The output also assumes that the
embosser is equipped with continuous-form tractor-fed paper and can emboss
across the page perforations to produce embossed images that are longer
than 11 inches. If your embosser doesn't operate in that mode, I don't know
what will happen to the bottom portion of the embossed image.

Considerably more detail could be preserved by enlarging the tactile image
and producing additional side-by-side panels, but there is a trade-off
between more detail and the practical aspects of handling tactile images
that are 2, 3, 4, or more pages wide.

This is an image of a battery showing the plates on either side, the
positive and negative ions in the solution between the plates, the + and -
poles at the top of the plates, etc. Not a great image, but probably useful
as a supplement to the description of the image in the textbook.

Dick Baldwin

On Wed, Jan 25, 2012 at 1:52 PM, Sina Bahram <sbahram at nc.rr.com> wrote:

>
> I had in mind the pro version of acrobat, but that solution hardly scales.
>
> Let me think on this for a bit.
>
> Website: www.SinaBahram.com
> Twitter: @SinaBahram
>
> -----Original Message-----
> From: blindmath-bounces at nfbnet.org [mailto:blindmath-bounces at nfbnet.org]
> On Behalf Of Richard Baldwin
> Sent: Wednesday, January 25, 2012 2:25 PM
> To: john.gardner at orst.edu; Blind Math list for those interested in
> mathematics
> Cc: accessibleimage at freelists.org
> Subject: Re: [Blindmath] Extracting bitmap images from pdf files
>
> Sina,
>
> I have tried the pdf to html image harvesting trick with several onsite
> converters. Dozens of websites claim to offer the conversion service. Of
> the four or five that I tried, only one seemed to do the job and as I
> recall, it was limited to 2-mbyte pdf files, which is a problem. Also, on
> that one, whenever I harvested the image from the html page, I got a large
> blank image with a small image somewhere on it. Although I can crop the
> small image from the large blank image, sight is required to pull that off.
>
>  Do you have a favorite way to convert pdf files to html files?
>
> Thanks,
> Dick Baldwin
>
> On Wed, Jan 25, 2012 at 12:33 PM, John Gardner <john.gardner at orst.edu
> >wrote:
>
> > Dick, if someone is fortunate enough to have a ViewPlus embosser and IVEO
> > Creator Pro, she can have pretty good access to images.
> > * import the PDF into IVEO Creator Pro.
> > * Check the PDF to find which pages have images of interest and emboss
> > those
> > pages.
> > * Put the embossed page on the touchpad and "Zoom Rectangle" by clicking
> on
> > diagonally-opposite corners of the image of interest.  This will zoom
> that
> > image to occupy maximum size the page will permit.
> > * Emboss the zoomed image and read it using the touchpad.  Horizontal
> text
> > on the image should read when pressed.  The OCR in Creator Pro works
> really
> > well with PDF's so if the resolution is at all decent, the text usually
> is
> > OCRed well.
> > * Go back to the original image and do same for any other image on that
> > page.  Repeat for images on other pages.
> >
> > Note that a sighted person can skip the first embossing step and just
> zoom
> > those images.  Handy to have sighted people around, but if there aren't
> it
> > just takes a little longer.  By the way, that sighted person can create
> > overlays on important objects on the graphic and label them to improve
> > accessibility even more.
> >
> > John
> >
> > -----Original Message-----
> > From: blindmath-bounces at nfbnet.org [mailto:blindmath-bounces at nfbnet.org]
> > On
> > Behalf Of Richard Baldwin
> > Sent: Wednesday, January 25, 2012 10:08 AM
> > To: BlindMath Mailing List; accessibleimage at freelists.org
> > Subject: [Blindmath] Extracting bitmap images from pdf files
> >
> > Many blind students receive electronic textbooks in pdf format.
> >
> > Many textbooks contain lots of images.
> >
> > Many images are poorly described in textbooks.
> >
> > Various ways to convert bitmap images into tactile images are available
> --
> > some fairly good, some not so good, some very poor. However, regardless
> of
> > the quality of the conversion to tactile format, you must have the
> original
> > image file in order to get anything.
> >
> > I have tried four or five different online file conversion sites in an
> > attempt to find a clean way that a blind student can extract the images
> > from a pdf textbook file without success. Different sites have different
> > problems, but they all seem to have some kind of problems that make it
> very
> > difficult to extract the images from pdf files.
> >
> > Has anyone identified an online site or downloadable program that is
> > available either free or at a reasonable price to cleanly extract the
> > images from pdf files, which often range up to 10 or more megabytes  or
> > more in size?
> >
> > Thanks,
> > Dick Baldwin
> >
> > --
> > Richard G. Baldwin (Dick Baldwin)
> > Home of Baldwin's on-line Java Tutorials
> > http://www.DickBaldwin.com
> >
> > Professor of Computer Information Technology
> > Austin Community College
> > (512) 223-4758
> > mailto:Baldwin at DickBaldwin.com
> > http://www.austincc.edu/baldwin/
> > _______________________________________________
> > Blindmath mailing list
> > Blindmath at nfbnet.org
> > http://nfbnet.org/mailman/listinfo/blindmath_nfbnet.org
> > To unsubscribe, change your list options or get your account info for
> > Blindmath:
> >
> >
> http://nfbnet.org/mailman/options/blindmath_nfbnet.org/john.gardner%40orst.e
> > du
> >
> >
> > _______________________________________________
> > Blindmath mailing list
> > Blindmath at nfbnet.org
> > http://nfbnet.org/mailman/listinfo/blindmath_nfbnet.org
> > To unsubscribe, change your list options or get your account info for
> > Blindmath:
> >
> >
> http://nfbnet.org/mailman/options/blindmath_nfbnet.org/baldwin%40dickbaldwin.com
> >
>
>
>
> --
> Richard G. Baldwin (Dick Baldwin)
> Home of Baldwin's on-line Java Tutorials
> http://www.DickBaldwin.com
>
> Professor of Computer Information Technology
> Austin Community College
> (512) 223-4758
> mailto:Baldwin at DickBaldwin.com
> http://www.austincc.edu/baldwin/
> _______________________________________________
> Blindmath mailing list
> Blindmath at nfbnet.org
> http://nfbnet.org/mailman/listinfo/blindmath_nfbnet.org
> To unsubscribe, change your list options or get your account info for
> Blindmath:
> http://nfbnet.org/mailman/options/blindmath_nfbnet.org/sbahram%40nc.rr.com
>
>
> _______________________________________________
> Blindmath mailing list
> Blindmath at nfbnet.org
> http://nfbnet.org/mailman/listinfo/blindmath_nfbnet.org
> To unsubscribe, change your list options or get your account info for
> Blindmath:
>
> http://nfbnet.org/mailman/options/blindmath_nfbnet.org/baldwin%40dickbaldwin.com
>

-- 
Richard G. Baldwin (Dick Baldwin)
Home of Baldwin's on-line Java Tutorials
http://www.DickBaldwin.com

Professor of Computer Information Technology
Austin Community College
(512) 223-4758
mailto:Baldwin at DickBaldwin.com
http://www.austincc.edu/baldwin/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SigFiles.zip
Type: application/zip
Size: 1752 bytes
Desc: not available
URL: <http://nfbnet.org/pipermail/blindmath_nfbnet.org/attachments/20120125/d622cffa/attachment.zip>