RE: Help-octave Digest, Vol 164, Issue 7

[Joe Tusek]

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Subject: Help-octave Digest, Vol 164, Issue 7

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Today's Topics:

   1. help -  image representation not filling figure window (Joe Tusek)
   2. Re: help -  image representation not filling figure window
      (Pantxo)


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Message: 1
Date: Tue, 5 Nov 2019 10:13:59 +0000
From: Joe Tusek <address@hidden>
To: "address@hidden" <address@hidden>
Subject: help -  image representation not filling figure window
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="utf-8"

Hi,

When plotting images using imshow, the resulting images resist expansion 
outside of their present boundaries under mouse control. Whilst in many cases 
it could be argued that the image does not warrant expansion, enabling it can 
reduce visual stress and is common when wanting to inspect pixels. Maybe there 
is already a plot option for this?

The following code generates the attached image, zzf_ed = eye(512,256); [H, 
theta, rho] = hough (zzf_ed, 'Theta', [-10:0.2:10]); imshow (mat2gray (H), 
[],"XData",theta,"YData",rho); axis on; xlabel("theta [degrees]"); ylabel("rho 
[pixels]");

There is a sequence of mouse and button operations that seem to do most of what 
I am after but are a very cumbersome way of achieving it. This involves using 
the Tools menu on the figure and enabling mouse zoom. This then enables me to 
expand the axes of the plot across the figure window and then by zooming in on 
the image I can achieve some improvement in zoom. It's not really giving the 
same outcome as just dragging the corners of the image to form a new plot 
boundary for the figure, which is what I was expecting to be able to do.

Also, a right-click figure copy function would be handy.

I am using W10 and Oct 5.1.0.

Regards
Joe

Joe Tusek (BE MBA)
Technical Director
23 Warabrook Boulevard, Warabrook, NSW 2304 P +61 2 4961 9000  M +61 418 669 250
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Message: 2
Date: Tue, 5 Nov 2019 09:36:10 -0600 (CST)
From: Pantxo <address@hidden>
To: address@hidden
Subject: Re: help -  image representation not filling figure window
Message-ID: <address@hidden>
Content-Type: text/plain; charset=us-ascii

Joe Tusek wrote
> Hi,
> 
> When plotting images using imshow, the resulting images resist 
> expansion outside of their present boundaries under mouse control. 
> Whilst in many cases it could be argued that the image does not 
> warrant expansion, enabling it can reduce visual stress and is common 
> when wanting to inspect pixels. Maybe there is already a plot option for this?
> 
> The following code generates the attached image, zzf_ed = 
> eye(512,256); [H, theta, rho] = hough (zzf_ed, 'Theta', [-10:0.2:10]); 
> imshow (mat2gray (H), [],"XData",theta,"YData",rho); axis on; 
> xlabel("theta [degrees]"); ylabel("rho [pixels]");
> 
> There is a sequence of mouse and button operations that seem to do 
> most of what I am after but are a very cumbersome way of achieving it. 
> This involves using the Tools menu on the figure and enabling mouse 
> zoom. This then enables me to expand the axes of the plot across the 
> figure window and then by zooming in on the image I can achieve some 
> improvement in zoom. It's not really giving the same outcome as just 
> dragging the corners of the image to form a new plot boundary for the 
> figure, which is what I was expecting to be able to do.
> 
> Also, a right-click figure copy function would be handy.
> 
> I am using W10 and Oct 5.1.0.
> 
> Regards
> Joe
> 
> Joe Tusek (BE MBA)
> Technical Director
> 23 Warabrook Boulevard, Warabrook, NSW 2304 P +61 2 4961 9000  M +61 
> 418 669 250
> 
> 
> 
> 
> imageplot_narrow.png (15K)
> &lt;https://octave.1599824.n4.nabble.com/attachment/4694469/0/imageplo
> t_narrow.png&gt;

Hi,

Imshow is a high level convenience function that besides creating an image 
object to display your data, sets up the axes to have the most commonly 
expected properties including data aspect ratio [1 1 1] (see the "image"
option in the help string for "axis" function). If you want a better control 
over how your image will be displayed, create a bare image object and set axes 
properties directly:

zzf_ed = eye(512,256);
[H, theta, rho] = hough (zzf_ed, 'Theta', [-10:0.2:10]); image (theta, rho, 
mat2gray (H), "cdatamapping", "scaled"); set (gca, "colormap", gray ())

HTH,

Pantxo



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Thanks, that certainly does work. I think the limitations of the Figure window 
though, will need to be addressed through an improvement request.

Joe