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Thread Subject:
heat map

Subject: heat map

From: Jessica

Date: 19 Mar, 2008 00:20:25

Message: 1 of 6

Hi,

I was wondering if anyone could give some suggestions about
going about the following task:

I have a photograph and a long list of x-y coordinates that
fall within it. Is it possible to overlay these coordinates
atop the photograph to generate a heat map?

Thanks,
Jessica

Subject: heat map

From: roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson)

Date: 23 Mar, 2008 00:54:57

Message: 2 of 6

In article <frpm89$50r$1@fred.mathworks.com>,
Jessica <jyorzinski@ucdavis.edu> wrote:
>I have a photograph and a long list of x-y coordinates that
>fall within it. Is it possible to overlay these coordinates
>atop the photograph to generate a heat map?

I do not see the connection between "coordinates" and "heat map" ??

Are these coordinates essentially contour plot coordinates
of equal heat? Or is there a specific heat that accompanies
each coordinate? If so, then does every grid point in the
photograph have an associated heat? If not then what interpolation
should be used to determine the heat at points not specified?

For the end result, do you want -just- a heat image? Or do you
want the heat image "blended" with the underlying photograph?
--
'Roberson' is my family name; my given name is 'Walter'.

Subject: heat map

From: ImageAnalyst

Date: 23 Mar, 2008 01:01:35

Message: 3 of 6

On Mar 18, 8:20=A0pm, "Jessica " <jyorzin...@ucdavis.edu> wrote:
> Hi,
>
> I was wondering if anyone could give some suggestions about
> going about the following task:
>
> I have a photograph and a long list of x-y coordinates that
> fall within it. Is it possible to overlay these coordinates
> atop the photograph to generate a heat map?
>
> Thanks,
> Jessica

------------------------------------------------------
Jessica:
I assume the x-y coordinates are the isotherm contour lines. Just use
plot(x,y) to overlay these coordinates on the "photograph." Be sure
to use "hold on" before plot() otherwise it will blow away your image.
Regards,
ImageAnalyst

Subject: heat map

From: Jessica

Date: 27 Apr, 2008 20:53:02

Message: 4 of 6

roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
message <fs49p1$h1a$1@canopus.cc.umanitoba.ca>...
> In article <frpm89$50r$1@fred.mathworks.com>,
> Jessica <jyorzinski@ucdavis.edu> wrote:
> >I have a photograph and a long list of x-y coordinates
that
> >fall within it. Is it possible to overlay these
coordinates
> >atop the photograph to generate a heat map?
>
> I do not see the connection between "coordinates"
and "heat map" ??
>
> Are these coordinates essentially contour plot coordinates
> of equal heat? Or is there a specific heat that
accompanies
> each coordinate? If so, then does every grid point in the
> photograph have an associated heat? If not then what
interpolation
> should be used to determine the heat at points not
specified?
>
> For the end result, do you want -just- a heat image? Or
do you
> want the heat image "blended" with the underlying
photograph?
> --
> 'Roberson' is my family name; my given name is 'Walter'.

Hi,

Thanks for the response. I am trying to generate an image
like the one found on this website:
http://www.intranetjournal.com/articles/200503/Heatmap.jpg

Each coordinate would be worth the same amount but the
different colors would just represent how numerous they are.

I would like to still be able to see the underlying picture.

Thanks,
Jessica

Subject: heat map

From: ImageAnalyst

Date: 28 Apr, 2008 01:26:42

Message: 5 of 6

On Apr 27, 4:53=A0pm, "Jessica " <jyorzin...@ucdavis.edu> wrote:
> rober...@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
> message <fs49p1$h1...@canopus.cc.umanitoba.ca>...
>
>
>
>
>
> > In article <frpm89$50...@fred.mathworks.com>,
> > Jessica =A0<jyorzin...@ucdavis.edu> wrote:
> > >I have a photograph and a long list of x-y coordinates
> that
> > >fall within it. Is it possible to overlay these
> coordinates
> > >atop the photograph to generate a heat map?
>
> > I do not see the connection between "coordinates"
> and "heat map" ??
>
> > Are these coordinates essentially contour plot coordinates
> > of equal heat? Or is there a specific heat that
> accompanies
> > each coordinate? If so, then does every grid point in the
> > photograph have an associated heat? If not then what
> interpolation
> > should be used to determine the heat at points not
> specified?
>
> > For the end result, do you want -just- a heat image? Or
> do you
> > want the heat image "blended" with the underlying
> photograph?
> > --
> > 'Roberson' is my family name; my given name is 'Walter'.
>
> Hi,
>
> Thanks for the response. I am trying to generate an image
> like the one found on this website:http://www.intranetjournal.com/articles=
/200503/Heatmap.jpg
>
> Each coordinate would be worth the same amount but the
> different colors would just represent how numerous they are.
>
> I would like to still be able to see the underlying picture.
>
> Thanks,
> Jessica- Hide quoted text -
>
> - Show quoted text -

----------------------------------------------------------------------------=
--------------------
Jessica:
It looks like you're trying to overlay a "gaze map," like one that is
constructed from eye-tracker experiments, onto an image. In your
example image it looks like the Hue of the image has been replaced by
your gaze map image. Here's what you can do:
1. From your list of coordinates build an gaze map image. There are
many, many ways to do this so pick one, for example, drop down a
Gaussian of a certain size onto the image at each coordinate.
2. Convert your original image to HSI color space.
3. Replace the H band of the original image with the appropriately
scaled gaze map. You scaled it (possibly non-linearly) depending on
what gaze value you want to be at what color.
4. Convert your HSI image back into RGB color space.
Regards,
ImageAnalyst

Subject: heat map

From: Jessica

Date: 28 Apr, 2008 02:25:03

Message: 6 of 6

ImageAnalyst <imageanalyst@mailinator.com> wrote in message
<eb4bf06a-01d3-4f4a-9281-
7d52e316b599@t54g2000hsg.googlegroups.com>...
> On Apr 27, 4:53=A0pm, "Jessica " <jyorzin...@ucdavis.edu>
wrote:
> > rober...@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
> > message <fs49p1$h1...@canopus.cc.umanitoba.ca>...
> >
> >
> >
> >
> >
> > > In article <frpm89$50...@fred.mathworks.com>,
> > > Jessica =A0<jyorzin...@ucdavis.edu> wrote:
> > > >I have a photograph and a long list of x-y
coordinates
> > that
> > > >fall within it. Is it possible to overlay these
> > coordinates
> > > >atop the photograph to generate a heat map?
> >
> > > I do not see the connection between "coordinates"
> > and "heat map" ??
> >
> > > Are these coordinates essentially contour plot
coordinates
> > > of equal heat? Or is there a specific heat that
> > accompanies
> > > each coordinate? If so, then does every grid point in
the
> > > photograph have an associated heat? If not then what
> > interpolation
> > > should be used to determine the heat at points not
> > specified?
> >
> > > For the end result, do you want -just- a heat image?
Or
> > do you
> > > want the heat image "blended" with the underlying
> > photograph?
> > > --
> > > 'Roberson' is my family name; my given name
is 'Walter'.
> >
> > Hi,
> >
> > Thanks for the response. I am trying to generate an
image
> > like the one found on this
website:http://www.intranetjournal.com/articles=
> /200503/Heatmap.jpg
> >
> > Each coordinate would be worth the same amount but the
> > different colors would just represent how numerous they
are.
> >
> > I would like to still be able to see the underlying
picture.
> >
> > Thanks,
> > Jessica- Hide quoted text -
> >
> > - Show quoted text -
>
> ----------------------------------------------------------
------------------=
> --------------------
> Jessica:
> It looks like you're trying to overlay a "gaze map," like
one that is
> constructed from eye-tracker experiments, onto an image.
In your
> example image it looks like the Hue of the image has been
replaced by
> your gaze map image. Here's what you can do:
> 1. From your list of coordinates build an gaze map
image. There are
> many, many ways to do this so pick one, for example, drop
down a
> Gaussian of a certain size onto the image at each
coordinate.
> 2. Convert your original image to HSI color space.
> 3. Replace the H band of the original image with the
appropriately
> scaled gaze map. You scaled it (possibly non-linearly)
depending on
> what gaze value you want to be at what color.
> 4. Convert your HSI image back into RGB color space.
> Regards,
> ImageAnalyst

Hi ImageAnalyst,

Thanks for these suggestions! I am indeed trying to
create 'gaze maps' from data gathered from an eye tracker.
I am relatively new to programming so would appreciate any
further details you can provide about the instructions you
listed above. I found a script for converting between RGB
and HSI so that is not a problem for me. Therefore, steps 1
and 3 are were I could use a little more assistance. Are
there any particular commands already set-up to perform
these actions?

Thanks,
Jessica

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