[Blindmath] Version 0.0.1 of ShapeExtractor02 is now availablefordownload

Fri Feb 17 04:06:59 UTC 2012

Speaking of the Mona Lisa, here she is in five-level grayscale and also in
enhanced black and white.

Dick Baldwin

On Thu, Feb 16, 2012 at 11:37 AM, John Gardner <john.gardner at orst.edu>wrote:

> This is a very interesting discussion.  I did some investigations similar
> to
> what Dick is doing last year with a Tiger embosser.  In the Tiger tab there
> are controls for contrast and brightness, adjustable from 0 to 99.
> (Actually negative values are available too, but they seem not to be
> useful).  These controls have been in ViewPlus printer drivers for years
> but
> are undocumented because of exactly the same problem Dick is encountering.
> They can be very useful, but I can find no reliable statistical way to
> predict what the best setting should be.  By trial and error, one can
> certainly sharpen up images and bring out features, but unless a sighted
> person does it, it is very tedious.  Actually it is pretty tedious anyhow.
> I like Dick's slider that can make instant adjustment.  I hope we can
> incorporate this into ViewPlus printer drivers eventually.
>
> I should also mention that I have worked on a simple automatic way to
> convert color into tactile patterns.  We will put this experimental method
> into a printer driver soon as a user option.  I really like it - it does a
> beautiful job of differentiating things like color sections on pie charts.
> It may or may not be useful for understanding the portrait of Mona Lisa.
>
> J Gardner
>
>
> -----Original Message-----
> From: blindmath-bounces at nfbnet.org [mailto:blindmath-bounces at nfbnet.org]
> On
> Behalf Of Michael Whapples
> Sent: Thursday, February 16, 2012 2:29 AM
> To: Blind Math list for those interested in mathematics
> Subject: Re: [Blindmath] Version 0.0.1 of ShapeExtractor02 is now
> availablefordownload
>
> Hello,
> I was thinking of a different method. If the blind student is adjusting it
> then they are likely to have access to the embossing equipment (is this a
> reasonable assumption). So emboss a diagram near the middle of the range
> that normally gives a good result. This probably will give an idea if this
> mid point is too much black pixels or too few. Now if no
> knowledge/experience of what happens exists the user could then go halfway
> to the "normally" reasonable range and emboss that diagram. Again they
> probably will get an idea of which way to go again if it isn't clear at
> this
>
> point. A similar search can be continued until something good is found.
> Probably with use the user might be able to make a better guess from the
> initial embossed diagram and may decide to adjust from halfway through the
> reasonable range.
>
> A quick example: If you say generally the range 5% to 25% give reasonable
> results, then the first diagram might be done at 15%, if there are too many
> black pixels then they reduce it to 10 and try again. If still too much
> black pixels then may be go to 5% or may be 7.5%.
>
> I think some questions might be: Is it going to be linear, IE. is it
> correct
>
> for me to say go halfway? Another thing might be what is the smallest
> difference where any noticable change will be found IE. there probably is
> no
>
> point in trying 7.5 and then 7.6.
>
> Michael Whapples
>
> -----Original Message-----
> From: Richard Baldwin
> Sent: Thursday, February 16, 2012 12:58 AM
> To: Blind Math list for those interested in mathematics
> Subject: Re: [Blindmath] Version 0.0.1 of ShapeExtractor02 is now
> availablefordownload
>
> Hi Peter,
>
> As you have probably observed, a sighted person can adjust the slider and
> look at an onscreen display in order to produce an output file that meets
> some given visual criteria.
>
> The difficult issue is coming up with a criteria that a blind person can
> use to know that they have the algorithm parameters properly adjusted. I am
> open to suggestions in this regard.
>
> One criteria that I have been testing is based on the number of black
> pixels in the image. Having looked at dozens of images at random, I have
> concluded that for best results in most cases, the number of black pixels
> should range somewhere between 5-percent and 25-percent of the total number
> of pixels in the image. Any more than that and the tactile image probably
> won't be interpretable due to excessive black areas. Any less than that and
> there won't be much that can be interpreted in the tactile image.
>
> However, that is still a very large range and the optimal value differs
> from one image to the next. For example, a vector diagram containing a
> single vector in a pair of Cartesian axes usually needs to be on the low
> side for good results. However, if a background grid is placed on the
> coordinate system, the percentage of black pixels needs to be substantially
> increased or the grid and the vector won't be visible in the final tactile
> image.
>
> In some cases, with a good description, the blind user might be able to
> come up with a good guess regarding the percentage of black pixels to use.
> However, most descriptions aren't written with that criteria in mind so
> that is not something that can be counted on.
>
> Right now, the best that I can come up with is to emboss three images at 5,
> 10, and 15 percent and see which seems to be best. With that information,
> it is usually possible to make a good guess for the fourth embossed image.
>
> Once again, if anyone has any ideas in this regard, I would like to hear
> them.
>
> Thanks for the response,
> Dick Baldwin
>
> On Wed, Feb 15, 2012 at 4:21 PM, Peter Donahue <pdonahue2 at satx.rr.com
> >wrote:
>
> > Hello Dick and everyone,
> >
> > What are you doing to make the slider usable by a blind person? Keep up
> > the
> > great work.
> >
> > Peter Donahue
> >
> >
> > ----- Original Message -----
> > From: "Richard Baldwin" <baldwin at dickbaldwin.com>
> > To: "BlindMath Mailing List" <blindmath at nfbnet.org>;
> > <accessibleimage at freelists.org>
> > Sent: Wednesday, February 15, 2012 2:31 PM
> > Subject: [Blindmath] Version 0.0.1 of ShapeExtractor02 is now available
> > fordownload
> >
> >
> > There are about 16-million good reasons why the embossed version of a
> > full-color bitmap image often fails to produce satisfactory tactile
> > results. Begin with the fact that the embossing process often discards
> the
> > information content of more than 16-million colors ending up with what is
> > effectively black and white, or possibly black and white with two or
> three
> > shades of gray in between, depending on the embossing method.
> >
> > This is illustrated by the two round images in the attached image files.
> > One image shows a typical color wheel made up of a mixture of red, green,
> > and blue primary color values. The other image shows the result of
> > transforming that color image into a four-level grayscale image. The
> > black,
> > gray, and white bands in the grayscale image identify the original colors
> > that would probably be indistinguishable in a four-level embossed image
> of
> > the color wheel.
> >
> > Follow the loss of color information with the fact that, unless the
> > original image is very small, the spatial sampling is probably reduced by
> > a
> > factor of 5 to 10 in the embossed image with little or no consideration
> > being given to frequency aliasing that occurs in a brute-force spatial
> > re-sampling process.
> >
> > The bottom line is that it is difficult to emboss full-color bitmap
> images
> > and end up with high-quality tactile images.
> >
> > In some cases, it is possible to pre-process an image in a way that will
> > cause it to produce a better embossed result than would be the case
> > without
> > such pre-processing. The new free program named ShapeExtractor02 is
> > designed with that purpose in mind. I explain this more fully in the html
> > document that is attached to this message.
> >
> > The four attached images of the horse show what I mean by pre-processing
> > the image to produce an improved embossed image.
> >
> > One image shows a full-color image of a beautiful brown hourse.
> >
> > A second image shows a four or five level grayscale version of the horse
> > image. This is pretty much what you would see if you were to copy the
> > image
> > to a multi-level embosser. Essentially, you would see large areas of dots
> > whose heights are slightly different from dots in adjoining areas. It
> > remains to be seen if a blind student could pick a horse out of that. If
> > you were to copy this to a black and white (dot or no dot) embosser, you
> > probably would not get anything that would be recognizable as a horse.
> >
> > Another image shows a pre-processed version of the horse image with
> black,
> > white, and three levels of gray in between. The major difference between
> > this image and the simple grayscale image is that this image tends to
> > outline the salient features of the original image with black and fill in
> > the outline with shades of gray. Thus, you don't see large areas of
> pixels
> > all having the same color of gray. Instead, you see outlines of shapes
> > that
> > identify the salient features of the original image. That is why this
> > program is named ShapeExtractor. I believe that an embossed version of
> > this
> > image would be more recognizable as a horse than an embossed version of
> > the
> > grayscale image on a multi-level embosser.
> >
> > Another attached image shows a black and white version of the
> > pre-processed
> > image of the horse. I'm confident that this would be more recognizable
> > that
> > the grayscale image on a black and white embosser and would probably also
> > be more recognizable on a multi-level embosser..
> >
> > In all cases, a good description would be needed to help the student to
> > understand the embossed image.
> >
> > I am pleased to announce that Version 0.0.1 of the new program
> > named ShapeExtractor02 is now posted at
> > http://www.austincc.edu/baldwin/SWT-SVG/SVGDraw01.zip and is available
> for
> > free and immediate downloading. (To save space on the server, the new
> > program is encapsulated in a zip file along with some earlier programs.)
> > This new program was used to produce two of the horse images that are
> > attached to this message.
> >
> > This program accepts a bitmap image as input and writes the enhanced
> > output
> > in a jpg bitmap file that can be embossed using any process that accepts
> a
> > jpg file as input. For example, if you and your students are fortunate to
> > have access to an IVEO system, you could import the enhanced image into
> > IVEO and add audio descriptions of the key features of the image. Then
> > emboss the updated image on a Tiger and allow the student to explore the
> > upgraded image on an IVEO touchpad.
> >
> > The program makes it easy for sighted teachers and others who assist
> blind
> > students to enhance bitmap images for possible improved embosser
> > performance. An onscreen display shows the enhanced version of the image
> > so
> > it isn't necessary to emboss it to evaluate the success or lack thereof
> of
> > the enhancement process. An onscreen slider makes it possible to easily
> > adjust the enhancement parameters for best performance.
> >
> > This program can also be used by blind students for the same purpose
> using
> > default settings. Even though blind students can't operate the slider to
> > optimize the output, the default settings will often produce an improved
> > embossed image.
> >
> > To use this free program, simply download the zip file using the link
> that
> > is provided above, extract the contents of the zip file into an empty
> > Windows folder, read the file named __ReadMeFirst.txt, and start
> > processing
> > bitmap files.
> >
> > A copy of the user instruction file is attached to this message for
> direct
> > reading. Another copy of the instructions, with images intact, is
> > contained
> > in the attached zip file.
> >
> > Please let me know if this program works for you and provide suggestions
> > for improvement.
> >
> > 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/
> >
> >
> >
> >
> >
>
> ----------------------------------------------------------------------------
> ----
> >
> >
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>
>
> --
> 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/
> _______________________________________________
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-- 
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/
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