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<h1>Instructions for using the program named JpgToSig-A-01</h1>
<p>Version 0.0.1 2012.02.12<br />
Revised 02/12/12</p>
<h2>Table of contents</h2>
<ul>
<li><a href="#Introduction">Introduction</a><ul>
<li><a href="#Semi-theoretical_background">Semi-theoretical background</a><ul>
<li><a href="#The_answer_to_the_question">The answer to the question</a><ul>
<li><a href="#Loss_of_color_information">Loss of color
information</a><ul>
<li><a href="#The_billboard_example">The billboard example</a></li>
</ul>
</li>
<li><a href="#Loss_of_spatial_detail">Loss of spatial detail</a></li>
</ul>
</li>
<li><a href="#The_solution">The solution to the color loss problem</a><ul>
<li><a href="#Outlines">Outlines are good</a></li>
<li><a href="#Color_differences_are_paramount">Color differences are paramount</a></li>
<li><a href="#Camouflage">Camouflage</a></li>
<li><a href="#Emphasizing_outlines">Emphasizing outlines</a></li>
<li><a href="#Color_changes">Color changes</a></li>
<li><a href="#An_audio_speed_sensor">An audio speed sensor</a></li>
<li><a href="#Getting_back_to_outlines">Getting back to outlines</a></li>
<li><a href="#A_mathematical_description">A mathematical description</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><a href="#Operating_instructions">Brief operating instructions</a><ul>
<li><a href="#GUI_components">GUI components</a></li>
<li><a href="#Data_entry">Data entry and file selection</a></li>
<li><a href="#The_sliding_scale">The sliding scale</a></li>
<li><a href="#Sliding_scale_value_display">Sliding scale value display</a></li>
<li><a href="#Write_the_output_file">Write output files</a></li>
<li><a href="#Exit_the_program">Exit the program</a></li>
</ul>
</li>
<li><a href="#Fitting_the_embossed_image_to_the_page">Fitting the embossed image to the page</a><ul>
<li><a href="#Retention_of_the_salient_features_of_the_original_image">Retention of the salient features of the original image</a></li>
<li>
<a href="#Tactile_presentation_of_the_salient_features_of_the_original_image">Tactile presentation of the salient features of the original image</a><ul>
<li><a href="#A_12_dot_per_inch_embosser_example">A 12 dot-per-inch embosser example</a></li>
<li><a href="#A_100_pixel_per_inch_monitor">A 100 pixel-per-inch monitor</a></li>
<li><a href="#Poster_size_embossed_images">Poster size embossed images</a></li>
<li><a href="#Simulating_a_24-inch_embosser">Simulating a 24-inch embosser</a></li>
<li><a href="#The_maximum_allowable_number_of_panels">The maximum allowable number of panels</a></li>
<li><a href="#An_integer_number_of_panels">An integer number of panels</a></li>
<li><a href="#The_output_file_number_system">The output file numbering system</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#Detailed_operating_instructions">Detailed operating
instructions</a></li>
<ul>
<li><a href="#Embosser_width_in_inches">Embosser width in inches</a></li>
<li><a href="#Dots_per_inch">Dots per inch</a></li>
<li><a href="#Maximum_allowable_number_of_panels">Maximum allowable
number of panels</a></li>
<li><a href="#SelectAndProcessFile">Select file</a><ul>
<li><a href="#Allowable_file_types">Allowable file types</a></li>
<li><a href="#Processing_begins">Processing begins</a></li>
</ul>
</li>
<li><a href="#Slide_to_adjust_image">Slide to adjust threshold</a></li>
<li><a href="#Sliding scale value display">Sliding scale value display</a></li>
<li><a href="#Write_output_file(s)">Write output file(s) </a>
</li>
</ul>
</ul>
<h2><a name="Introduction">Introduction</a></h2>
<p>JpgToSig-A-01 is a program that is designed to make it easier for sighted
teachers and others who assist blind people to enhance bitmap images, convert them to SIG files, and emboss them in the
enhanced format on an embosser that accepts the Duxbury QuickTac SIG file format
for embossing graphics data.</p>
<p>The program is not accessible to blind users because it requires the use of a
mouse and a slider to adjust a threshold in the enhancement algorithm for best results on each
individual image.</p>
<p>The program applies a sophisticated image processing algorithm to the
full-color bitmap image for the purpose of identifying and
<a href="#Retention_of_the_salient_features_of_the_original_image">retaining the
salient features</a> of the image prior to converting to black and white format.</p>
<p>The program also employs a presentation format that is designed to provide an
enhanced
<a href="#Tactile_presentation_of_the_salient_features_of_the_original_image">
tactile presentation</a> of those salient features.</p>
<h3><a name="Semi-theoretical_background">Semi-theoretical background</a></h3>
<p>Why is it so difficult to produce tactile embossed images that are
recognizable by and useful to blind users? The answer is simple. The solution is not so
simple.</p>
<h4><a name="The_answer_to_the_question">The answer to the question</a></h4>
<p>In most cases, a digital image consists of an array of colored pixels where
any one pixel can take on more than 16 million colors.</p>
<p>Unless you are fortunate enough to have access to an embosser that produces
variable dot heights, an embossed output is analogous to a digital image
containing only two colors -- black and white. The situation is somewhat better
with variable dot height, which can represent black, white, and three or four
shades of gray.</p>
<p>However, this program is designed specifically for use with embossers that can only
display black and white, so the remaining discussion will concentrate on
the preparation of images for use on embossers of those types. I will publish a
different program later that is designed to use with embossers that produce dots
of different heights.</p>
<h5><a name="Loss_of_color_information">Loss of color information</a></h5>
<p>Part of the answer is that in order to emboss a digital image, we
must somehow map 16 million colors into two colors (black and white) and still cause those
two colors to portray the original image.</p>
<p>Assume, for example, that you were to divide the colors into two sets of
about 8 million colors each. Then assume that in order to emboss a bitmap image,
you were to convert every pixel whose color falls in one set to black and you
were to convert every pixel whose color falls in the other set to white.</p>
<p>The results that you get will depend entirely on chance and the chances for
success aren't very good. The chances are about 8 million to 1 that each pixel
will be indistinguishable from its neighbors in the final black and white
version.</p>
<h6><a name="The_billboard_example">The billboard example</a></h6>
<p>Assume, for example, that two of the primary colors, red and green, are
assigned to black and the third primary color, blue, is assigned to white. Now
assume that you emboss an image of a green rectangular billboard containing red
letters in front of a blue sky. The result would be a black rectangle on a white
background. The message being conveyed by the red letters would be completely
lost because they also would be converted to black and would be
indistinguishable from the billboard.</p>
<p>We need a better way to convert those 16 million colors to black and white. I
will explain a better way shortly.</p>
<h5><a name="Loss_of_spatial_detail">Loss of spatial detail</a></h5>
<p>The second part of the answer has to do with spatial sampling. A typical
500x500 bitmap image consists of an array of 250,000 colored pixels. Typical
embossers have dot resolutions ranging from 10 dots per inch on the low side to
25 dots per inch on the high side. Therefore, an 8x10
inch embossed image will typically contain somewhere between 8,000 and 50,000
dots (black) or spaces (white) depending on the embosser.</p>
<p>Fewer dots mean that less detail can be portrayed by the embossed image. For
example, a small circle in a bitmap image may come out looking more like a square
than a circle in
an embossed image. An arrowhead on a vector in a bitmap image may come out
looking like a random collection of a few dots in an embossed image.</p>
<p>Short of inventing an embosser with many more dots per inch, this is a very
difficult problem to solve. However, I do have a non-ideal approach to
alleviating the problem that I will describe later.</p>
<h4><a name="The_solution">The solution to the color loss problem</a></h4>
<p>Let me begin by saying that there is no single best solution to the problem
of color loss.
Different solutions may provide better results for different images. The
solution provided by this program is only one of several possible solutions.</p>
<h5><a name="Outlines">Outlines are good</a></h5>
<p>Coloring books used by small sighted children contain images consisting
almost entirely of the outlines of objects. However, once a student progresses
beyond childhood coloring books and enrolls in an art class, she learns that there are very few outlines
in nature. Consequently, there are usually very few outlines in digital images.</p>
<h5><a name="Color_differences_are_paramount">Color differences are paramount</a></h5>
<p>In general, the only
thing that distinguishes one object from another in a full color digital image is
the fact that the two objects are colored differently. As mentioned above, if
the scheme for converting the color image to black and white depends on
subdividing the colors into two groups, and simply mapping the colors into black
and white, much of the information will be lost in
the transformation from color to black and white.</p>
<h5><a name="Camouflage">Camouflage</a></h5>
<p>Animals and military combat troops use camouflage to avoid being seen by
predators or by the enemy. The purpose of camouflage is to eliminate outlines
and to prevent the recognition of common shapes.</p>
<p>For example, the colors of the feathers on a quail cause it to blend into its
surroundings and eliminate or reduce its visual outline. The chameleon and
certain undersea creatures can change their color to match that of their
surroundings, once again to eliminate or reduce their visual outline.</p>
<p>For purposes of embossing a digital image on a two-level embosser, we need a
way to un-camouflage the objects in the image.</p>
<h5><a name="Emphasizing_outlines">Emphasizing outlines</a></h5>
<p>Rather than eliminating outlines, the image processing algorithm used by this
program is designed to emphasize outlines. The objective is to cause each object
in an image to be described by a black outline against a white background.</p>
<h5><a name="Color_changes">Color changes</a></h5>
<p>The distinguishing characteristic among objects in a full-color digital image
is usually not the absolute colors themselves. Instead, the distinguishing characteristic is the
change in color from one object to the next. For example, I can invert the
colors in a color image so that every unique color is changed to a different
unique color and a sighted person will probably still be able to distinguish
among the different objects in the image.</p>
<p>Therefore, the primary characteristic of the algorithm used by this program
is not based the translation of absolute colors into black and white. Instead, it
is based on detecting the changes in color and reflecting those changes in black
and white.</p>
<h5><a name="An_audio_speed_sensor">An audio speed sensor</a></h5>
<p>This is analogous to installing a buzzer in your car that sounds off when
your rate of change of position (speed) exceeds a preset limit. The buzzer
doesn't care about your absolute position, it cares only about the rate of
change in position.</p>
<p>The algorithm used in this program doesn't care about absolute color, it
cares only about the rate of change of color.</p>
<h5><a name="Getting_back_to_outlines">Getting back to outlines</a></h5>
<p>The net effect of the algorithm is to convert the image back to the "coloring book" format of
black outlines on a white background. This is a format that seems to work well
for embossing images with a two-level embosser.</p>
<h5><a name="A_mathematical_description">A mathematical description</a></h5>
<p>For the mathematicians in the group, the enhancement algorithm simulates the
computation of the first derivative of a five-dimensional surface (X, Y, red,
green, and blue) and the creation of a three-dimensional surface where the height of the
surface at a particular X-Y coordinate position represents the rate of change of color at
that position in the original image.</p>
<p>A slider is used to manually apply a level detector to the surface, producing
black pixels where the rate of change exceeds the threshold and producing white
pixels where the rate of change is less than the threshold. Thus, peaks in the
surface are represented as black islands in a sea of white.</p>
<h2><a name="Operating_instructions">Brief operating instructions</a></h2>
<p>JpgToSig-A-01 is a GUI application designed for use by sighted instructors
and others who assist blind people. It is not designed to be accessible for
unassisted use by the blind. (I will publish a different version of the program
later that is designed for unassisted use by the blind.) The user interface consists
of labels, data entry fields, a sliding scale, a small display window, two
buttons, and a large onscreen visual display.</p>
<h3><a name="GUI_components">GUI components</a></h3>
<p>When the program starts running, focus is on a component that I refer to as
home base. It reads "Start here and tab down." As you tab down, you will
encounter the following components in order, which are labeled as shown. I will explain
the purpose of each component in later sections of this document.</p>
<ul>
<li><a name="Edit_field">Edit field</a> -
<a href="#Embosser_width_in_inches">Embosser width in inches</a></li>
<li>Edit field - <a href="#Dots_per_inch">Dots per inch</a></li>
<li>Edit field - <a href="#Maximum_allowable_number_of_panels">Maximum allowable number of panels</a></li>
<li>Button - <a href="#SelectAndProcessFile">Select file</a></li>
<li>Sliding scale - <a href="#Slide_to_adjust_image">Slide to adjust threshold</a></li>
<li>Display - <a href="#Sliding scale value display">Sliding scale value display</a></li>
<li>Button - <a href="#Write_output_file(s)">Write output file(s)</a></li>
</ul>
<h3><a name="Data_entry">Data entry</a> and file selection</h3>
<p>Enter data into the three edit fields and then press the button
labeled "Select file.". When you press that button, a
standard file selection dialog will appear allowing you to select
a bitmap image file for processing.</p>
<h3><a name="The_sliding_scale">The sliding scale</a></h3>
<p>When you select an image file for processing, the program will begin running
the image enhancement algorithm described <a href="#The_solution">earlier</a> The slider
on the scale will move to the center position with a value of 50 and a black and
white version of the selected image will appear in a onscreen display.</p>
<p>A threshold value that is used by the enhancement algorithm can be adjusted to show more less detail. Detail
decreases you move the slider to the left and increases as you move the slider
to the right. </p>
<p>Only you can decide what works best for any particular
image and you can use the slider to adjust the level of detail accordingly.</p>
<h3><a name="Sliding_scale_value_display">Sliding scale value display</a></h3>
<p>The sliding scale is calibrated from 0 on the left to 100 on the right. As
you move the slider, you should see the current position of the slider reflected
in a small read-only display immediately below the sliding scale.</p>
<h3><a name="Write_the_output_file">Write output file</a>(s)</h3>
<p>When you are satisfied with the image showing in the onscreen display, press
the button labeled "Write output file(s). This will cause one or more output
files to be written in the Duxbury sig file format. The files will be written
into the same folder as the input file that you <a href="#Data_entry">selected</a>
for processing earlier.</p>
<p>When the output SIG files have been written, you can use them to produce an
embossed version of the enhanced image. </p>
<p>At that point, you can either select another file for processing, or exit the
program.</p>
<h3><a name="Exit_the_program">Exit the program</a></h3>
<p>You can exit the program by selecting the X in the
upper-right corner of the graphical user interface.</p>
<h2><a name="Fitting_the_embossed_image_to_the_page">Fitting the embossed image
to the page</a></h2>
<p>In an earlier section, I explained the problem resulting from the
<a href="#Loss_of_spatial_detail">loss of spatial detail</a>. The program is designed to take full advantage of the paper size
and dot resolution capacity of
your embosser to produce embossed
tactile images that preserve the salient features of the original image.</p>
<p>When you run this program, you will provide information on embosser or paper
<a href="#Embosser_width_in_inches">width</a>, the number of
<a href="#Dots_per_inch">dots per inch</a> that your embosser can punch, and the
maximum allowable <a href="#Maximum_allowable_number_of_panels">number of panels</a>.</p>
<p>Two important concepts were paramount in the design of the
program:</p>
<ol>
<li>Identification and retention of the salient features of the original image
prior to discarding the color information</li>
<li>Tactile presentation of the salient features of the original image</li>
</ol>
<h3><a name="Retention_of_the_salient_features_of_the_original_image">Retention
of the salient features of the original image</a></h3>
<p>A full-color bitmap image can contain more than sixteen million different
colors applied to images with typical widths of 250 to 600 pixels. Obviously,
some images are wider and some are narrower.</p>
<p>Typical embosser widths range from 100 to 350 dots. Embossers with variable
dot heights can probably represent three or four colors (dot heights or shades
of gray) and embossers without variable dot height can only represent black and
white. This program is designed specifically for use with embossers that do not
support variable dot height.</p>
<p>Regardless of how you approach the problem, the conversion of a full-color
image to an array of Braille dots requires that a tremendous amount of
information be discarded in the process.</p>
<p>As explained <a href="#The_solution">earlier</a>, this program is designed to retain as much information as possible about the
salient features of the original image. This is accomplished by applying a
sophisticated image processing algorithm to the full-color image and extracting
those features prior to
discarding the color information and transforming the image into a black and
white image.</p>
<h3>
<a name="Tactile_presentation_of_the_salient_features_of_the_original_image">
Tactile presentation of the salient features of the original image</a></h3>
<p>Doing an effective job of retaining the salient features of the original
image in the conversion from full color to black and white is only part of the
problem. The other part of the problem is finding an effective way to present
the enhanced black and white information in a tactile format based on only ten to twenty-five
Braille dots per inch.</p>
<h4><a name="A_12_dot_per_inch_embosser_example">A 12 dot-per-inch embosser
example</a></h4>
<p>For talking purposes, let's assume that you have an embosser with 12 dpi that
supports continuous form paper. Assume that the machine can emboss across the perforations that
separate pages. If the paper is 8.5 inches wide, you can create embossed images
that are about 100 dots wide and any length. (When the image is converted to
landscape mode, you can create embossed images that are about 100 dots high and
any width.)</p>
<h4><a name="A_100_pixel_per_inch_monitor">A 100 pixel-per-inch monitor</a></h4>
<p>My 22-inch monitor can display about 100 pixels per inch. Thus, a full width embossed
image on your 12 dpi embosser would be about one inch wide on my monitor. If I
begin with a bit-mapped image that is 300 pixels wide and scale it down until it
is only 100 pixels wide, I will have lost a lot of information even if I retain
16 million colors. (I will lose a lot more information if I convert it
to black and white in the process.) In all probability, the original image that is three inches wide conveys a lot
more information than the image that is only one inch wide.</p>
<h4><a name="Poster_size_embossed_images">Poster size embossed images</a></h4>
<p>I believe that up to a point, the same concept should apply to embossed
tactile images. For example, a poster-sized tactile image that is 300 dots wide
(about 24 inches at 12 dpi) should convey more information than the same image
scaled down to make it 100 dots or 8 inches wide.</p>
<p>The real question then has to do with overall size limitations in the
interpretation of tactile material by blind users. In other words, can a blind
user effectively extract the same information from an embossed image that is 24
inches wide that I can extract from a corresponding visual image that is 300
pixels wide? I don't know the answer to that question.</p>
<h4><a name="Simulating_a_24-inch_embosser">Simulating a 24-inch embosser</a></h4>
<p>As far as I know, there are no commercially available embossers that can
handle paper that is 24 inches wide. Therefore, this program subdivides the
enhanced image into panels that are intended to be embossed and placed
side-by-side for interpretation. The program produces a separate output file for
embossing each panel.</p>
<p>The program also adds a grid of individual dots on
one-inch centers as an aid in the interpretation of large tactile images.</p>
<h4><a name="The_maximum_allowable_number_of_panels">The maximum allowable
number of panels</a></h4>
<p>The purpose of the input parameter named
<a href="#Maximum_allowable_number_of_panels">Maximum allowable number of
panels</a> is to specify the overall size of the final embossed image
consisting of one or more panels placed side-by-side for interpretation.</p>
<p>For example, if the enhanced version of your original image is 350 pixels wide, you have a paper
width of 100 dots, and you specify one panel, the enhanced image will be scaled
down to fill one panel. (Note that in the enhancement process, excessive white
margins are discarded keeping only that portion of the enhanced image that
contains black pixels.)</p>
<p>If you specify two panels, the enhanced image will be scaled down to fill two
panels.</p>
<p>If you specify four panels, the enhanced image will be
scaled up to fill four panels.</p>
<p>If you specify five panels, the enhanced image
will still be scaled up to fill four panels, and you will get four
output files instead of five. In other words, excessive up-scaling is not
allowed, because up-scaling a bitmap image to a size larger than the original
doesn't add information.</p>
<h4><a name="An_integer_number_of_panels">An integer number of panels</a></h4>
<p>Up-scaling to fill an integer number of panels is allowed, however. This makes it
possible to easily determine which panel of a multi-panel display will contain a
feature that is identified in a single-panel version of the enhanced image. For example,
a feature that is found in the right-most portion of a single-panel version of
an enhanced image will also appear much larger and with more detail in the right-most
panel of a four-panel version of the same enhanced image.</p>
<p>When more than one output file is produced, you should emboss them all. Then
lay the embossed images side-by-side (perhaps using tape to attach them
together) for interpretation. The image produced from
the first output file should be placed on the left and the image produced from
the last output file should be placed on the right.</p>
<h4><a name="The_output_file_number_system">The output file numbering system</a></h4>
<p>The names of the output files are based on the name of the input image file. The output files are numbered (beginning with -0 and continuing through -1,
-2, etc.) so that you can keep them in order. However, this information is not
embossed, so you will need to manually mark the embossed images as you remove
them from the embosser so that you can refer to them later in the proper order.</p>
<p>If the enhanced image is wider than it is tall, the image is automatically
rotated into landscape mode. In this case, the output file name will include
"-R-" to tell you that the images has been rotated. In this case, the output
file numbered 0 will contain the top of the image and the output file with the
largest number will contain the bottom of the image.</p>
<p>Regardless of whether the output is normal or landscape mode, the name of the
input file is embossed in the top left corner of each output panel.</p>
<h2><a name="Detailed_operating_instructions">Detailed operating instructions</a></h2>
<h3><a name="Embosser_width_in_inches">Embosser width in inches</a></h3>
<p>This is the width in inches within which your embosser can punch dots. Stated
differently, this is the distance in inches from the leftmost dot that your
embosser can punch to the rightmost dot that your embosser can punch on the same
horizontal row for a given paper size.</p>
<p>The purpose of this input parameter was discussed in detail earlier in the
section titled "<a href="#Fitting_the_embossed_image_to_the_page">Fitting the
embossed image to the page</a>." </p>
<p>Simply enter the width information into the field, being careful to include
only numeric characters and a decimal point.</p>
<h3><a name="Dots_per_inch">Dots per inch</a></h3>
<p>This is the maximum number of dots that your embosser can punch in a
horizontal inch. You may need to look this up in your embosser documentation. I
believe, for example, that the Tiger embossers punch 20 dots per inch. The
Phoenix embosser is advertised to punch 25 dots per inch. Although I'm not
certain, I believe that the Juliet embosser punches 12 dots per inch, and I am led to believe that some
older embossers could only punch 10 dots per inch.</p>
<p>The purpose of this input parameter was discussed in detail earlier in the
section titled "<a href="#Fitting_the_embossed_image_to_the_page">Fitting the
embossed image to the page</a>." </p>
<p>The program assumes that the number of dots per vertical inch is the same as
the number of dots per horizontal inch. If this is not the case, the program
should still work, but you should enter a value that is the lesser of the two.
The result will be a loss of aspect ratio. In other words, an embossed circle
probably won't look like a circle, but will look like an ellipse instead.</p>
<p>Simply enter the information into the field, being careful to include
only numeric characters and a decimal point if needed.</p>
<h3><a name="Maximum_allowable_number_of_panels">Maximum allowable number of
panels</a></h3>
<p>The purpose of this input parameter was discussed in detail earlier in the
section titled "<a href="#Fitting_the_embossed_image_to_the_page">Fitting the
embossed image to the page</a>." </p>
<h3><a name="SelectAndProcessFile">Select file</a></h3>
<p>Pressing this button opens a standard file selection dialog. The dialog
allows you to select a file for processing. Processing begins when you select
the file and close the dialog.</p>
<h4><a name="Allowable_file_types">Allowable file types</a></h4>
<p>The image processing portion of this program was written using a multimedia
library provided by Georgia Tech University. I'm unsure as to all of the
different image file types that it will support. I know that the program will
support image files of <a name="types_jpg">types jpg</a>, bmp, and png, so the program is written to
allow you to easily select image files of those types. (The program will also allow you
to select a file of any type, but a little extra effort is required.)</p>
<p>If you are interested in
routinely processing image files of types other than those <a href="#types_jpg">
listed above</a>, contact me by email and provide a sample image file. I will
test the file, and if it can be supported, I will update the program to include
image files of that type.</p>
<h4><a name="Processing_begins">Processing begins</a></h4>
<p>As mentioned above, processing begins when you select the file and close the
dialog. At this point, you can begin moving the slider to adjust the image in
the onscreen display. </p>
<p>Also, at this point, the values for <strong>Embosser width in inches</strong>,
<strong>Dots per inch</strong>,
and <strong>Maximum allowable number of panels</strong> are fixed. Changing the values in those
fields will have no effect until you select another file for processing.</p>
<h3><a name="Slide_to_adjust_image">Slide to adjust threshold</a></h3>
<p>As mentioned earlier, when you select an image file for processing, the
program will begin running an image enhancement algorithm that is designed to
emphasize the salient features of the original image in the embossed version of
the image.</p>
<p>At that point, the slider on the scale will move to the center position with
a value of 50 and a black and white version of the selected image will appear in
a onscreen display.</p>
<p>A threshold used by the enhancement algorithm can be adjusted to show more or less detail. You can
decrease the detail by moving the slider to the left and you can increase the
detail by moving the slider to the right.</p>
<p>Depending on the speed of your computer, you may find that the slider is
sluggish and difficult to move. Just be patient. One approach is to press the
slider with the mouse and then move the mouse pointer to the location where you
want the slider to go, even if the slider doesn't move. As soon as the computer
finishes the current task, an updated image will appear in the onscreen display
and the slider will move to that position.</p>
<p>Another way to move the slider is to click the mouse in the track to the left
or the right of the slider. This will cause the slider to move in very small increments.
This is useful in the final stages of adjusting the threshold to cause the
algorithm to
produce the desired output.</p>
<p>Only you can decide what works best for any particular image and you can use
the slider to adjust the image accordingly.</p>
<h3><a name="Sliding scale value display">Sliding scale value display</a></h3>
<p>Also as mentioned earlier, the sliding scale is calibrated from 0 on the left
to 100 on the right. As you move the slider, you should see the current position
of the slider reflected in a small read-only display immediately below the
sliding scale. Note, however, that depending on the speed of your computer, you
may also find that updates to the display are also somewhat sluggish.</p>
<h3><a name="Write_output_file(s)">Write output file(s)</a></h3>
<p>When you click this button, the enhanced image in its current state will be
converted to Duxbury Quick Tac sig file format and written into one or more
output files with an extension of .sig. The files will be written into the same
folder from which the original image file was read.</p>
<p>The names of the sig files will be based on the name of the image file to
which they pertain. The numbering system for the files was described
<a href="#The_output_file_number_system">earlier</a>.</p>
<p>Any sig files in that folder with names based on the name of the image file
will be deleted and/or overwritten. Therefore, if you would like to create and
emboss several sets of sig files for the same image file with different
threshold values, you will need to copy the sig files into a different folder
(or manually rename them) before creating the next set of output files.</p>
<p>Dick Baldwin<br/>
baldwin@dickbaldwin.com</p>
<p>-end-</p>