Matlab Process Images

uifigure
└── uigridlayout
    ├── viewer2d          ← image container (left/main pane)
    │   └── imageshow
    └── uipanel           ← controls (right/side pane)
        └── uislider, uibutton, uidropdown, ...

fig = uifigure(Name="Image Processor");
gl = uigridlayout(fig, [1 2], ColumnWidth={"1x", 200});

% Image viewer (left)
v = viewer2d(gl);
im = imageshow(img, Parent=v);

% Controls panel (right)
pnl = uipanel(gl, Title="Controls");
pgl = uigridlayout(pnl, [4 1], RowHeight={30, 30, 30, "1x"});

% Add controls
sld = uislider(pgl, Limits=[0 1], Value=0.5);
sld.ValueChangedFcn = @(src, ~) updateThreshold(im, img, src.Value);

function updateThreshold(im, img, thresh)
    bw = imbinarize(img, thresh);
    im.Data = bw;          % Replace the displayed image
    % or
    im.OverlayData = bw;   % Show mask as overlay on original
end

% Interactive drawing (blocks until user finishes)
roi = uidraw(v, "polygon");            % Wait="drawing" (default)
roi = uidraw(v, "rectangle", Wait="accept");  % Blocks until Enter or accept icon — lets user adjust shape before returning

% Programmatic placement (non-interactive)
roi = uidraw(v, "rectangle", Position=[50 50 100 80], Wait="none");

% Rectangle: [xmin ymin width height]
roi = uidraw(v, "rectangle", Position=[50 50 100 80], Wait="none");

% Circle: [x y radius] or [x y z radius]
% Ellipse: [x y semix semiy] or [x y semix semiy theta]
% Angle: similar — optional z in center coordinate

% Polygon/polyline/freehand: Nx2 or Nx3
roi = uidraw(v, "polygon", ...
    Position=[50 50; 150 50; 150 150; 50 150], Wait="none");

% Point: [x y] or [x y z]
roi = uidraw(v, "point", Position=[100 100], Wait="none");

roi = uidraw(v, "polygon");
mask = createMask(roi);  % Binary mask matching displayed image size

% Interactive: draw multiple, press Enter or accept icon when done
rois = uidraw(v, "polygon", Wait="multiple");

% Programmatic: pass multiple positions as rows of a matrix
rois = uidraw(v, "rectangle", Position=[50 50 100 80; 200 200 60 60]);

% All viewer callbacks were introduced in R2026b

% Click on viewer content — image, volume, or surface
v.ObjectClickedFcn = @(~,evt) onObjectClicked(evt);

% Camera callbacks — after camera settles vs. during movement
v.CameraMovedFcn  = @(~,~) updateStatusBar(v.CameraZoom);
v.CameraMovingFcn = @(~,~) showMovingIndicator();   % fires continuously while moving

% Annotation lifecycle callbacks
v.AnnotationAddedFcn   = @(~,evt) onAnnotationAdded(evt);
v.AnnotationMovedFcn   = @(~,evt) onAnnotationMoved(evt);
v.AnnotationRemovedFcn = @(~,evt) onAnnotationRemoved(evt);

% Iterate all annotations
for roi = v.Annotations'
    roi.Color = [1 0 0];
end

% Index directly
v.Annotations(1).Label = "Region A";

% Count
n = numel(v.Annotations);

v.SpatialUnits = "mm";        % display labels show "mm"
roi.Position                  % still in pixel coordinates
roi.Position * pixelSpacing   % convert yourself

% Pass all positions in one call
rects  = uiannotate(v, "rectangle", positions);  % N-by-4: [x y w h] per row
circs  = uiannotate(v, "circle",    positions);  % N-by-3: [x y r] per row
pts    = uiannotate(v, "point",     positions);  % N-by-2: [x y] per row
arrows = uiannotate(v, "arrow",     positions);  % N-by-4: [x1 y1 x2 y2] (endpoints) or N-by-5: [x y u v mag] (direction+magnitude) per row

% Avoid — forces a render after every single property change
for i = 1:numel(rois)
    rois(i).Color = newColors(i,:);
    drawnow  % do not do this in a loop
end

% Prefer — let the viewer process all changes together
for i = 1:numel(rois)
    rois(i).Color = newColors(i,:);
end

v = viewer2d;
im = imageshow(img, Parent=v);
mask = uipaint(im, BrushSize=15);  % Blocks until user finishes

im = imageshow(img);
mask1 = uipaint(im, BrushSize=10, OverlayValue=1);
mask2 = uipaint(im, BrushSize=10, OverlayValue=2);

% Programmatic zoom reset button
btn = uibutton(pgl, Text="Reset View");
btn.ButtonPushedFcn = @(~,~) set(v, CameraZoom=1);

% Focus viewer on a specific image region (R2026a)
v.CameraViewport = [x y width height];

% Set view to a standard angle on a 3-D viewer (R2026a)
viewangle(v3d, 45, 30);  % azimuth, elevation

% Make viewer display-only (disable all user interaction)
v.Interactions = "none";

% Hide or auto-hide toolbar for cleaner app UI
v.Toolbar = "off";     % always hidden
v.Toolbar = "hover";   % appears on mouse-over only

gl = uigridlayout(fig, [1 2]);
v1 = viewer2d(gl);
v2 = viewer2d(gl);
imageshow(original, Parent=v1);
imageshow(processed, Parent=v2);

linkviewers([v1 v2]);  % Synchronized pan/zoom

% Crop to a rectangular box around a detected region (R2023b)
v.CropRegion = [xmin ymin zmin; xmax ymax zmax];

% Clear the crop
v.CropRegion = [];

% Programmatic-only crop with no user interaction
v.CropRegion = [xmin ymin zmin; xmax ymax zmax];
v.CropInteractions = "none";

% Inverted crop — hide the interior, show the surroundings
v.CropMode = "exclusive";

ax = uiaxes(gl);
imshow(img, Parent=ax);  % Legacy: axes-based display

roi = drawpolygon(ax);       % Interactive polygon
roi = drawrectangle(ax, Position=[50 50 100 80]);  % Programmatic
mask = createMask(roi);

addlistener(roi, "ROIMoved", @(src, ~) onROIMoved(src));
addlistener(roi, "MovingROI", @(src, evt) onMoving(evt));

im = imageshow(img);  % Image object, not the viewer

% Caliper: measure edge-pair distances interactively
cal = uicaliper(im, EdgeTransition="rising");
d   = cal.IntraEdgeDistance;   % distance within each edge pair

% T-square: point-to-line perpendicular distance
tsq = uitsquare(im);
d   = tsq.Distance;            % N-by-1 perpendicular distances

% Circle fit: fit circle to circular feature
circ = uifitcircle(im, Snap=true);
r    = circ.Radius;
c    = circ.Center;

% Angle: measure angle between two edges
ang   = uifitangle(im);
theta = ang.Theta;

tsq  = uitsquare(im, LineSnapMethod="closest", EdgeMap="canny");
snap(tsq);   % aligns tool to detected edges

function imageThresholdApp(img)
    fig = uifigure(Name="Threshold App");
    gl = uigridlayout(fig, [2 2], ...
        RowHeight={"1x", 40}, ColumnWidth={"1x", "1x"});

    % Original and result viewers
    v1 = viewer2d(gl); v1.Layout.Row = 1; v1.Layout.Column = 1;
    v2 = viewer2d(gl); v2.Layout.Row = 1; v2.Layout.Column = 2;
    linkviewers([v1 v2]);

    gray = im2gray(img);
    im1 = imageshow(img, Parent=v1);
    im2 = imageshow(imbinarize(gray), Parent=v2);

    % Threshold slider
    sld = uislider(gl, Limits=[0 1], Value=graythresh(gray));
    sld.Layout.Row = 2; sld.Layout.Column = [1 2];
    sld.ValueChangedFcn = @(src, ~) updateResult(im2, img, src.Value);
end

function updateResult(im, img, thresh)
    im.Data = imbinarize(img, thresh);
end