GoPro SuperView-like adaptive aspect ratio

bSplineResizeWidth.m

function [outImage, SAFEZONE] = bSplineResizeWidth(theSize, inImage, SAFEZONE, DEBUG)
    if nargin < 4 || isempty(DEBUG)
        DEBUG = 0;                                                          % Number of "safe zones"
    end
    if nargin < 3 || isempty(SAFEZONE)
        SAFEZONE = [37.5,62.5];                                             % Percent of image width
    end
    INTERPMETHOD = 'spline';

    %% Deal with input and output image sizes
    oldSize = size(inImage);                                                % Old image size
    newSize = [size(inImage,1),...                                          % New image size
               round(theSize(2)/theSize(1)*size(inImage,1))];
    fprintf('Input Image Size: %ux%u\n',oldSize(2),oldSize(1));
    fprintf('Transitional Image Size: %ux%u\n',newSize(2),newSize(1));
    fprintf('Output Image Size: %ux%u\n',theSize(2),theSize(1));

    %% Enable interactive selection if DEBUG is greater than 0
    if DEBUG > 0
        figure(1); clf;
        imshow(inImage); hold on
        % With DEBUG greater than 1, we allow for multiple "Safe Zones"
        for rows = 1:DEBUG
            [x(rows,1),y] = ginput(1);
            plot([x(rows,1) x(rows,1)],[1 size(inImage,1)],'r')
            [x(rows,2),y] = ginput(1);
            plot([x(rows,2) x(rows,2)],[1 size(inImage,1)],'g')
        end
        hold off;
        SAFEZONE = x/oldSize(2)*100;
    end

    %% Create spline remapping function
    xOld = linspace(1,oldSize(2),newSize(2));
    xNew = linspace(1,newSize(2),newSize(2));
    xOldOffset = (newSize(2)-oldSize(2))/2;
    xOld = xOld + xOldOffset;
    pointsX = xNew(1);
    pointsY = xOld(1);

    % Create "Safe Zones" around the regions protected by the user
    for SNUM = 1:size(SAFEZONE,1)
        SAFEZONEL = round(SAFEZONE(SNUM,1)/100 * newSize(2));
        SAFEZONEH = round(SAFEZONE(SNUM,2)/100 * newSize(2));

        diffL = (xNew(SAFEZONEL)-xOld(SAFEZONEL));
        diffH = (xNew(SAFEZONEH)-xOld(SAFEZONEH));
        theShift = ((diffH+diffL)/2);

        pointsX = [pointsX,xOld(SAFEZONEL:SAFEZONEH)+theShift];
        pointsY = [pointsY,xOld(SAFEZONEL:SAFEZONEH)];
    end

    pointsX = [pointsX,xNew(end)];
    pointsY = [pointsY,xOld(end)];

    splineF = csape(pointsX,pointsY,'variational');

    % Show mapping if DEBUG is not equal to 0
    if DEBUG ~= 0
        figure(2); clf;
        plot(xOld-xOldOffset,xOld-xOldOffset,'b', 'LineWidth',1, 'LineSmoothing','on'); hold on
        plot(xOld-xOldOffset,xNew,'r', 'LineWidth',1, 'LineSmoothing','on');
        remapping = fnval(splineF,xNew);
        plot(remapping-xOldOffset,xNew,'g', 'LineWidth',1, 'LineSmoothing','on');
        xlabel('Input')
        ylabel('Output')
        title('Input to Output Pixel Mapping')
        legend('Input Image Mapping','Output Image, Linear Mapping','Output Image, Spline Mapping','Location','SouthEast')
    end

    %% Interpolate old pixels to new coordinates
    newX = fnval(splineF,1:newSize(2),newSize(2))-(newSize(2)-oldSize(2))/2;% New image pixel X coordinates
    newY = linspace(1,oldSize(1),newSize(1));                               % New image pixel Y coordinates

    oldClass = class(inImage);                                              % Original image type
    inImage = double(inImage);                                              % Convert image to double precision for interpolation

    if numel(oldSize) == 2                                                  % Interpolate grayscale image
        outImage = interp2(inImage,newX,newY(:),INTERPMETHOD);
    else                                                                    % Interpolate RGB image
        outImage = zeros([newSize 3]);                                      % Initialize new image
        outImage(:,:,1) = interp2(inImage(:,:,1),newX,newY(:),INTERPMETHOD);    % Red
        outImage(:,:,2) = interp2(inImage(:,:,2),newX,newY(:),INTERPMETHOD);    % Green
        outImage(:,:,3) = interp2(inImage(:,:,3),newX,newY(:),INTERPMETHOD);    % Blue
    end

    inImage = cast(inImage,oldClass);                                       % Convert back to original image type
    outImage = cast(outImage,oldClass);                                     % Convert back to original image type
    outImage = imresize(outImage,[theSize(1) theSize(2)]);                  % Resize to output size

    if DEBUG > 0
        figure(1); clf;
        subplot(2,1,1);
        imshow(inImage);
        subplot(2,1,2);
        imshow(outImage);
    end
end

seamCarving.m

function [outImage, gradImage, seamImage] = seamCarving(theSize, inImage)
    addpath('MATLAB_Seam_Carving');

    %Remove this for full image seam carving
    % --------------------
    ARin = size(inImage,2)/size(inImage,1);
    inImage = imresize(inImage,[theSize(1), theSize(1) * ARin]);
    % --------------------

    outImage = double(inImage)/255;

    newcols = theSize(2);
    newrows = theSize(1);
    % Let's just resize the width based upon aspect ratio.  Remove this for
    % full image seam carving
    % --------------------
    newcols = round(size(inImage,1)*theSize(2)/theSize(1));
    newrows = size(inImage,1);
    disp(sprintf('Input Image Size: %ux%u',size(inImage,2),size(inImage,1)));
    disp(sprintf('Transitional Image Size: %ux%u',newcols,newrows));
    disp(sprintf('Output Image Size: %ux%u',theSize(2),theSize(1)));
    % --------------------

    Rcols = size(inImage,2)-newcols;
    Rrows = size(inImage,1)-newrows;

    gradImage = findEnergy(outImage);    %Finds the gradient image

    if abs(Rcols)>=size(inImage,2) || abs(Rrows)>=size(inImage,1)
        disp('Specified dimensions cannot be calculated, minimum image size is 1x1, and maximum is (2xCurrentSize)-1')
        outImage = inImage;
        return
    elseif Rrows==0 && Rcols==0
        disp('Specified dimensions are same as original')
        outImage = inImage;
        return
    end

    if Rcols>0
        clear M
        fprintf('Downsizing image by removing %u vertical seams\n',Rcols)
        M=removalMap(outImage,Rcols);
        outImage=SeamCut(outImage,M);
        gradImage=SeamCut(gradImage,M);
        seamImage=findSeamImg(gradImage);
    elseif Rcols<0
        clear M
        fprintf('Increasing image size by adding %u vertical seams\n',-Rcols)
        M=removalMap(outImage,abs(Rcols));
        outImage=SeamPut(outImage,M);
        gradImage=SeamPut(gradImage,M);
        seamImage=findSeamImg(gradImage);
    end

    if Rrows>0
        clear M
        fprintf('Downsizing image by removing %u horizontal seams\n',Rcols)
        Y=permute(outImage,[2,1,3]);
        M=removalMap(Y,Rrows);
        outImage=permute(SeamCut(Y,M),[2,1,3]);
        gradImage=SeamCut(gradImage.',M).';
        seamImage=findSeamImg(gradImage);
    elseif Rrows<0
        clear M
        fprintf('Increasing image size by adding %u horizontal seams\n',-Rcols)
        Y=permute(outImage,[2,1,3]);
        M=removalMap(Y,abs(Rrows));
        outImage=permute(SeamPut(Y,M),[2,1,3]);
        gradImage=SeamPut(gradImage.',M).';
        seamImage=findSeamImg(gradImage);
    end
end