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Topic: Cursor position on images
Replies: 4   Last Post: Jan 10, 2013 2:20 AM

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Murray Eisenberg

Posts: 2,097
Registered: 12/6/04
Re: Cursor position on images
Posted: Jan 10, 2013 2:20 AM
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I discovered the source of the problem: on Mac OS X it's Command + Click instead of Alt + Click!

And in the Documentation Center, e.g., ref/LocatorAutoCreate, it incorrectly and repeatedly gives Alt + Click, which is OK for Windows, but should be instead Command + Click for OS X.


On Jan 9, 2013, at 9:16 AM, Murray Eisenberg <murray@math.umass.edu> wrote:

> I still don't quite understand.
>
> In your original message, you included the following steps:
>
> Step 2: Enter the reference points at the plot axes into the input fields. Press Enter.
>
> Step3: Alt+Click on the point with x-coordinate x1.
> This brings up the first locator visible as a circle.
> Alt+Click on that with x2 which gives rise to the second locator.
> Adjust the locators, if necessary.
> Press the button ?Memorize scale X?.
>
> I think you're now saying to do things in an opposite order:
>
> (1) first put 2 by Alt+MouseClick put locators in two positions along, say, the x axis,
> (2) type two corresponding x coordinates and
> (3) then press the button "Memorize scale x",
> (4) then pull the same locators in two points along the y axis,
> (5) type the corresponding y values and
> (6) press the corresponding button.
>
> I presume this new (1) has a typo and should be simply:
>
> (1) first put Alt+MouseClick put locators in two positions along, say, the x axis,
>
> Assuming this new, opposite, order is what you intended,
>
> Still, no locator appears when I Alt-click anywhere in the image =

output after the copyCurve[pic] is evaluated. That's using Mathematica =
9.0.0 under Mac OS X 10.8.2.
>
> I now tried the same thing, with the same image, using the Windows =

version of Mathematica 9.0.0 under Windows 7 (running in a virtual =
machine in Parallels Desktop 8 on my same Mac). Now copyCurve _does_ =
work.
>
> So something's wrong with copyCurve on Mac. (Of course Alt in the Mac =

context means Option.) I tried the "obvious" things of Alt+Shift+Click, =
but that still does not produce a Locator.
>
> Wait=85the problem is with Alt-Click in Mathematica under OS X, for =

anything! For example, the code
>
> Manipulate[
> Graphics[{Line[u]}, PlotRange -> 2], {{u, {{-1, -1}, {1, 1}}},
> Locator, LocatorAutoCreate -> True}]
>
> from the Documentation Center does not work as expected in OS X: using =

Alt-Click does not create a new Locator!
>
> [In your original message, you partially reversed steps (1) and (2). =

There you said
> On Jan 9, 2013, at 3:33 AM, Alexei Boulbitch <Alexei.Boulbitch@iee.lu> =
wrote:
>
>> Dear Murray,
>>
>> In principle this:
>> pic = ExampleData[{"TestImage", "Lena"}]
>> copyCurve[pic]
>> is exactly how it should be used. I could not, however, repeat =

ExampleData[{"TestImage", "Lena"}] on my machine. It did not load the =
image for a long time, and after 5 minutes waiting I aborted it and =
copy-pasted Lena from Menu/Help/Image. I tried on my machine (Math9, PC, =
Win XP) with Lena obtained this way and it works. It is only necessary =
that the graphics you use has the head Image. Otherwise you can wrap it =
with Image. It also worked for me with PC/XP/Math8 (in which I have =
written it) and on PC/Win.7/Math9. I never tried it on Mac though.
>>
>> A minor thing is not quite correct with your sequence of actions. You =

should first put 2 by Alt+MouseClick put locators in two positions =
along, say, the x axis, type two corresponding x coordinates and then =
press the button "Memorize scale x", then pull the same locators in two =
points along the y axis, type the corresponding y values and press the =
corresponding button. Then use the same 2 locators at the first 2 points =
of the line you need to digitalize and add more locators where needed. =
The order x before y or y before x is of no importance. But of course, =
as soon as locators show up you immediately find the right way.
>>
>> Did you try to change the colour of the locators by the ColorSlider? =

They are red by default and may be poorly visible with Lena on the =
background.
>>
>> Best, Alexei
>>
>> Alexei BOULBITCH, Dr., habil.
>> IEE S.A.
>> ZAE Weiergewan,
>> 11, rue Edmond Reuter,
>> L-5326 Contern, LUXEMBOURG
>>
>> Office phone : +352-2454-2566
>> Office fax: +352-2454-3566
>> mobile phone: +49 151 52 40 66 44
>>
>> e-mail: alexei.boulbitch@iee.lu
>>
>>
>> -----Original Message-----
>> From: Murray Eisenberg [mailto:murray@math.umass.edu]
>> Sent: Tuesday, January 08, 2013 6:16 PM
>> To: mathgroup
>> Subject: Re: Cursor position on images
>>
>> Either I'm not understanding the instructions for copyCurve or else =

something is not working right for Mathematica 9.0.0 on Mac OS X. =
Example:
>>
>> pic = ExampleData[{"TestImage", "Lena"}]
>> copyCurve[pic]
>>
>> I now type into the x1, y1, x2, y2 input fields the values 0, 0, 200, =

200 respectively and press Enter.
>>
>> When I use Alt+Click, nothing happens -- I don't see any Locator.
>>
>> I also tried Shift+Alt+Click in case that's required for Mac, but =

still no action.
>>
>> On Jan 7, 2013, at 11:07 PM, Alexei Boulbitch =

<Alexei.Boulbitch@iee.lu> wrote:
>>
>>> I am sure this is straightforward but I cannot quite see how to do =
this. I have an image (jpg file, but could be any format if that =
matters). I want to be able to left click on the image and mark the =
point with a dot of some sort and collect the coordinates of the point =
(the coordinate system is fairly arbitrary). I then want to be able to =
repeat this as many times as required and end up with a list of the =
coordinates of the points clicked on for further manipulation. Clickpane =
should do the trick but I can't work out how.
>>>
>>> Any suggestions, thanks.
>>>
>>> Peter
>>>
>>> Hi, Peter,
>>>
>>> It is not exactly but very close to what you ask about. Below you =

will find a function along with its description. I use it to digitalize =
functions only available as curves on graphics, like taken from images. =
This might be what you have in mind. To try it just copy-paste any image =
into Mathematica, give it a name and apply the copyCurve function to it. =
Then act as it is described below. As the result you will get a list of =
points coordinates.
>>>
>>> Have fun, Alexei
>>>
>>>
>>>
>>> Description
>>>
>>> The function copyCurve enables one to get the coordinates of curve =

points from a plot found on an image and memorises them in a list =
entitled ?listOfPoints?
>>> Parameters:
>>>
>>> image is any image. It should have Head=Image, but may be also a =

Graphics object, since no specific functions of image have been used. I =
typically wrap it in Image[] statement.
>>>
>>> Controls:
>>>
>>> The Checkbox ?whiteLocatorRing? defines, if the locators are shown =

by a single color ring (unchecked), or with two rings, the outer having =
a color defined by the ColorSlider (see below), the innder being white. =
This may be helpful, if working with a too dark image.
>>>
>>> size controls the size of the image. The default value is 450. This =

slider is used to adjust the size to the one to enable the most =
comfortable work with the image plot.
>>>
>>> opacity controls the opacity of the line connecting the locators
>>>
>>> thickness controls the thickness of the double ring that forms each =

locator.
>>>
>>> lineThickness controls the thickness of the line connecting the =

locators
>>>
>>> color is the color slider that controls the color of the outer ring =

forming the locator and the line connecting them. The inned locator ring =
is always white.
>>>
>>> radius controls the radius of the locators.
>>>
>>> InputFields: should be supplied by the reference points x1 and x2 at =

the axis x, as well as y1 and y2 at the axis y.
>>>
>>> Buttons: The buttons ?Memorize scale X? and ?Memorize scale Y? =

should be pressed after the first two locators are placed on the =
corresponding reference points (presumably, located at the x or y axes). =
Upon pressing the reference points are memorized. The button ?Make list =
of the curve points? should be pressed at the end of the session. Upon =
its pressing the actual list of points representing the points of the =
curve is assigned to the global variable ?listOfPoints?
>>>
>>>
>>> Operation:
>>> Step 1: Execute the function with the name of the image containing =

the curve to be digitalized.
>>>
>>> Step 2: Enter the reference points at the plot axes into the input =

fields. Press Enter.
>>>
>>> Step3: Alt+Click on the point with x-coordinate x1. This brings up =

the first locator visible as a circle. Alt+Click on that with x2 which =
gives rise to the second locator. Adjust the locators, if necessary. =
Press the button ?Memorize scale X?.
>>>
>>> Step 4: Move the two already existing locators to the points with =

the coordinates y1 and y2. Press the button ?Memorize scale Y?. Now the =
both scales are captured.
>>>
>>> Step 5: Move the two already existing locators to the first two =

points of the curve to be captured. Alt+Click on other points of the =
curve. Each Alt+Click will generate an additional locator. Adjust =
locators, if necessary. To remove, Alt+Click on unnecessary locators.
>>>
>>> Step 6: Press the button ?Make the list...?. This assigns the =

captured list to the variable ?listOfPoints?. Done.
>>>
>>> The ?listOfPoints? is a global variable. It can be addressed =

everywhere in the notebook.
>>>
>>> The function copyCurve
>>>
>>> Clear[copyCurve];
>>>
>>> copyCurve[image_] :=
>>>
>>> Manipulate[
>>> DynamicModule[{pts = {}, x1 = Null, x2 = Null, y1 = Null,
>>> y2 = Null, X1, X2, Y1, Y2, \[CapitalDelta]X, \[CapitalDelta]Y, =

g,
>>> myRound},
>>>
>>> myRound[x_] := Round[1000.*x]/1000. // N;
>>>
>>> (* Begins the column with all the content of the manipulate *)
>>> Column[{
>>> (* Begin LocatorPane*)
>>> Dynamic@LocatorPane[Union[Dynamic[pts]],
>>> Dynamic@
>>> Show[{ReplacePart[image, {4, 2} -> size],
>>> Graphics[{color, AbsoluteThickness[lineThickness],
>>> Opacity[opacity], Line[Union[pts]]}]
>>> }], LocatorAutoCreate -> True,
>>> (* Begin Locator appearance *)
>>> Appearance -> If[whiteLocatorRing,
>>>
>>> Graphics[{{color, AbsoluteThickness[thickness],
>>> Circle[{0, 0}, radius + thickness/2]}, {White,
>>> AbsoluteThickness[thickness], Circle[{0, 0}, radius]}},
>>> ImageSize -> 10]
>>> ,
>>> Graphics[{{color, AbsoluteThickness[thickness],
>>> Circle[{0, 0}, radius + thickness/2]}},
>>> ImageSize -> 10]](* End Locator appearance *)
>>> ],(* End LocatorPane*)
>>>
>>> (* Begin of the block of InputFields *)
>>> , Row[{ Style["\!\(\*SubscriptBox[\(x\), \(1\)]\):"],
>>> InputField[Dynamic[x1],
>>> FieldHint -> "Type \!\(\*SubscriptBox[\(x\), \(1\)]\)",
>>> FieldSize -> 7, FieldHintStyle -> {Red}],
>>> Spacer[20], Style[" \!\(\*SubscriptBox[\(y\), \(1\)]\):"],
>>> InputField[Dynamic[y1],
>>> FieldHint -> "Type \!\(\*SubscriptBox[\(y\), \(1\)]\)",
>>> FieldSize -> 7, FieldHintStyle -> {Red}]
>>> }],
>>> Row[{ Style["\!\(\*SubscriptBox[\(x\), \(2\)]\):"],
>>> InputField[Dynamic[x2],
>>> FieldHint -> "Type \!\(\*SubscriptBox[\(x\), \(2\)]\)",
>>> FieldSize -> 7, FieldHintStyle -> {Red}],
>>> Spacer[20], Style[" \!\(\*SubscriptBox[\(y\), \(2\)]\):"],
>>> InputField[Dynamic[y2],
>>> FieldHint ->
>>> "Type \!\(\*SubscriptBox[\(y\), \(2\)]\)+Enter",
>>> FieldSize -> 7, FieldHintStyle -> {Red}]
>>> }],
>>> (* End of the block of InputFields *)
>>> (* Begin the buttons row *)
>>> Row[{Spacer[15],
>>> (* Begin button "Memorize scale X" *)
>>> Button["Memorize scale X",
>>> X1 = Min[Transpose[myRound /@ Union[pts]][[1]]];
>>> X2 = Max[Transpose[myRound /@ Union[pts]][[1]]];
>>> \[CapitalDelta]X = X2 - X1;
>>> ],(* End of button "Memorize scale X" *)
>>> Spacer[70],
>>> (* Begin button "Memorize scale Y" *)
>>> Button["Memorize scale Y",
>>> Y1 = Min[Transpose[myRound /@ Union[pts]][[2]]];
>>> Y2 = Max[Transpose[myRound /@ Union[pts]][[2]]];
>>> \[CapitalDelta]Y = Y2 - Y1;
>>> ](* End of button "Memorize scale Y" *)
>>>
>>>
>>> }],(* End the buttons row *)
>>> Spacer[0],
>>>
>>> (* Begin button "Make the list of the curve's points" *)
>>> Button[Style["Make the list of the curve's points" , Bold],
>>> g[{a_, b_}] := {(x1*X2 - x2*X1)/\[CapitalDelta]X +
>>> a/\[CapitalDelta]X*Abs[x2 - x1], (
>>> y1*Y2 - y2*Y1)/\[CapitalDelta]Y +
>>> b/\[CapitalDelta]Y*Abs[y2 - y1]};
>>> Clear[listOfPoints];
>>> listOfPoints = Map[myRound, Map[g, pts]]
>>> ](* End of button "Make the list..." *)
>>>
>>> }, Alignment -> Center](*
>>> End of column with all the content of the manipulate *)
>>> ],(* End of the DynamicModule *)
>>>
>>> (* The massive of sliders begins *)
>>> Column[{Row[{Control[{whiteLocatorRing, {True, False}}],
>>> Spacer[50]}],
>>> Row[{Spacer[32.35], Control[{{size, 450}, 300, 800}],
>>> Spacer[38.5`], Control[{{opacity, 0.5}, 0, 1}]}],
>>> Row[{Spacer[10.], Control[{{thickness, 1}, 0.5, 5}],
>>> Spacer[13.65], Control[{{lineThickness, 1}, 0, 10}] }],
>>> Row[{Spacer[22.8], Control[{color, Red}], Spacer[59.3],
>>> Control[{{radius, 0.5}, 0, 3}]}]
>>> }, Alignment -> Center],(* The massive of sliders ends *)
>>>
>>> (* Definitions of sliders *)
>>> ControlType -> {Checkbox, Slider, Slider, Slider, Slider,
>>> ColorSlider, Slider},
>>> ControlPlacement -> Top, SaveDefinitions -> True
>>> ];
>>> (* End of the function *)
>>>
>>>
>>> Alexei BOULBITCH, Dr., habil.
>>> IEE S.A.
>>> ZAE Weiergewan,
>>> 11, rue Edmond Reuter,
>>> L-5326 Contern, LUXEMBOURG
>>>
>>> Office phone : +352-2454-2566
>>> Office fax: +352-2454-3566
>>> mobile phone: +49 151 52 40 66 44
>>>
>>> e-mail: alexei.boulbitch@iee.lu

>>
>> ---
>> Murray Eisenberg =

murray@math.umass.edu
>> Mathematics & Statistics Dept.
>> Lederle Graduate Research Tower phone 413 549-1020 (H)
>> University of Massachusetts 413 =

545-2838 (W)
>> 710 North Pleasant Street fax 413 545-1801
>> Amherst, MA 01003-9305
>>
>>
>>
>>
>>
>>

>
> ---
> Murray Eisenberg =

murray@math.umass.edu
> Mathematics & Statistics Dept.
> Lederle Graduate Research Tower phone 413 549-1020 (H)
> University of Massachusetts 413 545-2838 =

(W)
> 710 North Pleasant Street fax 413 545-1801
> Amherst, MA 01003-9305
>
>
>
>
>


---
Murray Eisenberg =
murray@math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 413 549-1020 (H)
University of Massachusetts 413 545-2838 =
(W)
710 North Pleasant Street fax 413 545-1801
Amherst, MA 01003-9305









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