%% Grayscale Morphological Erosion
% Perform morphological erosion on a grayscale thumbnail image.
% Load a source image from a file. Select a portion of the image matching the desired test size.

frmOrig = imread('rice.png');
frmActivePixels = 64;
frmActiveLines = 48;
frmInput = frmOrig(1:frmActiveLines,1:frmActivePixels);
imshow(frmInput,'InitialMagnification',300)
title 'Input Image'

%
% Create a serializer object and define the inactive pixel regions. Make the number of inactive pixels following each active line at least double the horizontal size of the neighborhood. Make the number of lines following each frame at least double the vertical size of the neighborhood.

frm2pix = visionhdl.FrameToPixels(...
      'NumComponents',1,...
      'VideoFormat','custom',...
      'ActivePixelsPerLine',frmActivePixels,...
      'ActiveVideoLines',frmActiveLines,...
      'TotalPixelsPerLine',frmActivePixels+20,...
      'TotalVideoLines',frmActiveLines+20,...
      'StartingActiveLine',3,...     
      'FrontPorch',10);

%
% Create a filter object.

merode = visionhdl.GrayscaleErosion( ...
          'Neighborhood',ones(2,5));

%
% Serialize the test image by calling the serializer object. pixIn is a vector of intensity values. ctrlIn is a vector of control signal structures.
% Note: This syntax runs only in R2016b or later. If you are using an earlier release, replace each call of an object with the equivalent step syntax. For example, replace myObject(x) with step(myObject,x).

[pixIn,ctrlIn] = frm2pix(frmInput);

%
% Prepare to process pixels by preallocating output vectors.

[~,~,numPixelsPerFrame] = getparamfromfrm2pix(frm2pix);
pixOut = uint8(zeros(numPixelsPerFrame,1));
ctrlOut = repmat(pixelcontrolstruct,numPixelsPerFrame,1);

%
% For each pixel in the padded frame, compute the morphed value. Monitor the control signals to determine the latency of the object. The latency of a configuration depends on the number of active pixels in a line and the size of the neighborhood.

foundValIn = false;
foundValOut = false;
for p = 1:numPixelsPerFrame  
    if (ctrlIn(p).valid && foundValIn==0)
        foundValIn = p;
    end
    [pixOut(p),ctrlOut(p)] = merode(pixIn(p),ctrlIn(p));
    if (ctrlOut(p).valid && foundValOut==0)
        foundValOut = p;
    end
end
sprintf('object latency is %d cycles',foundValOut-foundValIn)

%
% Create a deserializer object with a format matching that of the serializer. Convert the pixel stream to an image frame by calling the deserializer object. Display the resulting image.

pix2frm = visionhdl.PixelsToFrame(...
      'NumComponents',1,...
      'VideoFormat','custom',...
      'ActivePixelsPerLine',frmActivePixels,...
      'ActiveVideoLines',frmActiveLines);
[frmOutput,frmValid] = pix2frm(pixOut,ctrlOut);
if frmValid
    figure
    imshow(frmOutput, 'InitialMagnification',300)
    title 'Output Image'
end

% Copyright 2012 The MathWorks, Inc.