imgca

Get current axes containing image

Syntax

ax = imgca

ax = imgca(fig)

Description

ax = imgca returns the current axes that contains an image. The current axes can be in a regular figure window or in an Image Tool window. Note that the current axes that contains an image might not be the same as the most recently accessed axes.

If no figure contains an axes that contains an image, then imgca creates a new axes.

example

ax = imgca(fig) returns the current axes that contains an image in the specified figure.

Examples

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Get Axes Containing Image

Open Live Script

Read a grayscale image into the workspace.

I = imread('coins.png');
imshow(I)

Figure contains an axes object. The hidden axes object contains an object of type image.

Convert the image into a binary image.

bw = imbinarize(I);
imshow(bw)

Figure contains an axes object. The hidden axes object contains an object of type image.

Fill holes in the binary objects, then calculate the centroids of the objects.

bw2 = imfill(bw,'holes');
s = regionprops(bw2, 'centroid');
centroids = cat(1,s.Centroid);

Display the original image and a plot of the centroids in the same figure window. Note that the current axes contains the plot of the centroids, not the displayed image.

subplot(1,2,1)
imshow(I)
subplot(1,2,2)
plot(centroids(:,1),centroids(:,2),'*')
axis image

Figure contains 2 axes objects. Axes object 1 contains a line object which displays its values using only markers. Hidden axes object 2 contains an object of type image.

The direction of the y-axis is reversed for images. For equivalent comparison of the image and the plot of the centroids, reverse the y-axis direction of the plot. To get the most recent axes, which contains the plot of the centroids, use the gca function.

h = gca;
h.YDir = 'reverse';

Use imgca to get the most recent axes containing an image. Note that this axes is not the most recent axes. Overlay the centroids in red asterisks on the image.

hIm = imgca;
hold(hIm,'on')
plot(hIm,centroids(:,1),centroids(:,2),'r*')
hold(hIm,'off')

Figure contains 2 axes objects. Axes object 1 contains a line object which displays its values using only markers. Hidden axes object 2 contains 2 objects of type image, line. One or more of the lines displays its values using only markers