MATLAB: Resize an Image while preserving aspect ratio in MATLAB Report Generator R2018a

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I would like to resize my image in MATLAB Report Generator but preserve the aspect ratio. I am using the method described in the link below, but I have not found an easy way to preserve the aspect ratio.

https://www.mathworks.com/help/rptgen/ug/create-and-format-images.html

Best Answer

See the example which shows how if you only specify the "Height" in the "<image>.Style" property and not the "Width", then the aspect ratio is preserved.

import mlreportgen.dom.*
%create document
d = Document('imageArea2','pdf');
%create two images, origional and resized
img_orig = Image('circle.png');
img_resize = Image('circle.png');
%resize one image
img_resize.Style  = {Height('2.5in')}; %the new height we want in inches
%add both to document and view
append(d,img_orig);
append(d,img_resize);
close(d);
rptview(d.OutputPath);

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MATLAB: How to center an image horizontally and vertically in a PDF created with Report Generator

To center an image in a report programmatically , you can modify the "Style" property of the image. The "Style" property of an image and other DOM document objects is a cell array of format objects, which you can use to style the DOM document object. Here is an example of how you can add a "HAlign" object to "Style" property of the "thePlot" image to center it in the PDF:

plotPath = getSnapshotImage(fig, R);
halign = mlreportgen.dom.HAlign('center');
thePlot.Style = [thePlot.Style(:)' {halign}];

However, adding a "VAlign" format object to the "Style" property of the image will not vertically align the image to the center of the page. PDF viewers honor the "VAlign" property only for DOM objects that are children of objects that have a specifiable height. Although pages have a specifiable height, they are not DOM objects so adding a "VAlign" object to the style property of an image that is a child of a page will not center the image. However, you can vertically align an image using the "VAlign" format object on a page if the image is a child of a 1 by 3 invisible table whose width and height are equivalent to the page body's width and height. To see an example, open the script "alignImage.m" attached and look at the "centerImage" function in the script for details..

MATLAB: Does imshow image shift the other plots and text on the UIAxes in app designer

When 'imshow' is called, it rearranges a few of the axes properties of app.UIAxes. It changes the direction of the y-axis ('YDir'), the modes of both the aspect ratios ('PlotBoxAspectRatioMode' and 'DataAspectRatioMode'), and the values of the aspect ratios ('PlotBoxAspectRatio' and 'DataAspectRatio'). We will need to preserve the original values and reassign them after 'imshow' is called.

The first row of pixels within an image is normally at the top. By default, the 'imshow' function inverts the y-axis direction when the image is displayed on an axes by setting the 'YDir' property to 'reverse.' To revert the y-axis direction after calling 'imshow', set the 'YDir' property to 'normal'. Then, to preserve the orientation of the image, flip the image using 'flip'.

Next, the 'imshow' function sets the 'DataAspectRatioMode' property of app.UIAxes to 'manual' and the 'PlotBoxAspectRatioMode' to 'auto'. The 'DataAspectRatio' property of app.PlotLegend is then rearranged to match the ratio of the image, and the 'PlotBoxAspectRatioMode' modifies itself accordingly.

In the code below, the original 'PlotBoxAspectRatio' is preserved, then the 'PlotBoxAspectRatioMode' is set to 'manual' while the 'DataAspectRatioMode' is set to 'auto'. Finally, the 'PlotBoxAspectRatio' is reassigned to the property's original value and the 'DataAspectRatio' property modifies itself accordingly.

          % Button pushed function: Button
          function ButtonPushed(app, event)
              v = [60,0; 75,0; 75,2; 60,2];
              f = [1, 2, 3, 4, 1];
              sqHandle = patch(app.UIAxes,'vertices', v, 'faces', f, ...
                  'FaceColor', 'k', 'LineStyle', 'none');
              txtHandle = text(app.UIAxes, 80, 0, 'test text','Fontsize',12,'VerticalAlignment', 'bottom');
              hold(app.PlotLegend,'on');
              pbarOriginal = pbaspect(app.UIAxes); % preserve the original PlotBoxAspectRatio
              I = imread('myImage.jpg');
              I = flip(I); % flip the image
              imshow(I,'Parent',app.UIAxes,'XData',[90,95],'YData',[0,2]);
              % Revert the properties back to their original values
              app.UIAxes.YDir = 'normal';
              app.UIAxes.PlotBoxAspectRatioMode = 'manual';
              app.UIAxes.DataAspectRatioMode = 'auto';
              app.UIAxes.PlotBoxAspectRatio = pbarOriginal;
          end

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Related Solutions

MATLAB: How to center an image horizontally and vertically in a PDF created with Report Generator

MATLAB: Does imshow image shift the other plots and text on the UIAxes in app designer

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