Image Processing, how do I create a draggable square cursor and to calculate avg and std of ROI

Hello all, I'm working on a project that requires me to filter out an image and then create a pixel region square that will hoover over a particular region of interest of the resultant image. The image is corrupted with radiation and I need to observe a particular region of this image. I have performed the filtering and used the impixelregion function which creates a pixelregion rectangule and a default window to view the ROI for the pixels of an image. However, i need the pixelregion rectangule to be of square dimension rather than rectangular.Upon specifying the region of interest by the pixelregion square, I also need to calculate the average pixel intensity and standard deviation for that region, and for the output to be displayed on the bottom half of the the default window with the pixel values at the bottom of that window. I tried to manipulate the impixelregion but to no avail. If some were to be kind to assist me in this problem. I will be grateful

[Image Analyst]

What do you mean by square cursor? Normally the cursor is an arrow but turns to crossed lines when using ginput(), or a spinning blue circle in Windows if you do this:

    % Change mouse pointer (cursor) to a circle or the "wait" cursor as defined by your operating system.
    % QUIRK: use 'watch' and you'll actually get your "wait" cursor, 
  % not a watch.
    set(gcf,'Pointer','watch');

What does it mean to have a square cursor? You mean like the mouse cursor is a tiny little square shape?

[Genus]

I made an error, it should be a pixelregion square which hoovers over a specific region similar to the pixelregion rectangle which hoovers over a ROI. But in this case its a square rather than a rectangle. Thanks

Answer 1

[Sean de Wolski]

doc imrect

And look at its method createMask

[Genus]

Yes, I have looked at imrect and the createmask technique. The createmask function notes that it returns a binary image of an input image, here my input image is rectangular, how do i manipulate createmask to produce a second image that is square. I also need this in the contex of impixelregion with the default screen displayed. thanks

[Image Analyst]

Set setFixedAspectRatioMode to true to maintain a square as you adjust the handles at the edges and corners of the rectangle displayed by imrect() over the image.

[Genus]

To image analyst the manipulation you mentioned, should be done in the imrect function.Am i correct in that assesment? What if I hypothetically wanted to manipulate the impixelregion function as to make adjustments to the function that creates the pixelregion rectangle that is exhibited below, how would one manipulate this to obtain a square and also calculate the average and standard deviation. The function is exhibited from line 220 to 254 in the impixelregion function. thanks

function zoomOut(varargin)

        min_zoom = getMinimumPixelRegionMag(scrollpanelAPI.getViewport(),hIm);

        candidate_zoom = scrollpanelAPI.getMagnification() / 1.25;
        if candidate_zoom >= min_zoom
            scrollpanelAPI.setMagnification(candidate_zoom);
        else

            rect_pos = scrollpanelAPI.getVisibleImageRect();
            image_rect = [im_xdata(1)-0.5, im_ydata(1)-0.5, im_xdata(2),  im_ydata(2)];

            rect_aspect_ratio = rect_pos(3) / rect_pos(4);

            candidate_height = image_rect(3) / rect_aspect_ratio;
            constrained_in_height = candidate_height > image_rect(4);

            getCenterX = @(pos) mean([pos(1),pos(1)+pos(3)]);
            getCenterY = @(pos) mean([pos(2),pos(2)+pos(4)]);

            % If requested zoom is less than minimum zoom, rectangle is either
            % constrained in width or constrained in height
            if constrained_in_height
                cx = getCenterX(rect_pos);
                cy = getCenterY(image_rect);
            else
                cx = getCenterX(image_rect);
                cy = getCenterY(rect_pos);
            end
            scrollpanelAPI.setMagnificationAndCenter(min_zoom,cx,cy)
        end

    end % zoomOut

end % createToolbar

[Image Analyst]

I haven't used impixelregion() so I can't help you.