How can i create a table that will contains the pixel values that i get from impixel()?

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Stephani Kanga
Stephani Kanga on 20 Nov 2020
Commented: Jemima Pulipati on 25 Nov 2020
I want to display the values from impixel to a uitable but, as the user is going to choose the points, the values are not constant so i can't initialize the table's data. How can i read the values from impixel and then put it in the table(RGB) along with two other columns (Name, Color)?
P = impixel() ;
Table = uitable(Tab1,'Units','normalized','Position',[.0 .1 1 .6]);
Table.ColumnName = {'Name','RGB','Color'};
Table.ColumnEditable = [true false false];
Table.RowName = 'numbered';
[numSelections,numCols] = size(P);
for i = 1 :numSelections-1
cell(i).name ='Label '+i;
cell(i).rgb = P(i,1);
cell(i).color = 'Color'+ i ;
end
Table.Data = cell2table(cell);

Answers (1)

Jemima Pulipati
Jemima Pulipati on 23 Nov 2020
Edited: Jemima Pulipati on 23 Nov 2020
Hello,
The impixel() accepts the image as an argument and returns the values of the pixels selected interactively on the image.
image = imread('peppers.png');
P = impixel(image) ;
The points on the image can be selected using normal button clicks but the last point has to be selected using 'Shift - click'.
Here is the modified code using the impixel() and storing the data in a uitable.
image = imread('peppers.png');
P = impixel(image) ;
% Specifying a parent container for uitable
f = uifigure;
Table = uitable(f,'Units','normalized','Position',[.0 .1 1 .6]);
Table.ColumnName = {'Name','RGB','Color'};
Table.ColumnEditable = [true false false];
Table.RowName = 'numbered';
[numSelections,numCols] = size(P);
% Pre allocating the array for speed
cellArray = cell(numSelections-1,3);
for i = 1 :numSelections-1
% storing the values in a cell array
cellArray(i,:) = {"Label"+num2str(i), P(i,1), "Color"+ num2str(i)};
end
Table.Data = cell2table(cellArray);
The output of this code is
NOTE: The number of values displayed in the table depend on the number of iterations, the loop runs. Since, you are running the loop till 'numSelections - 1' the last point selected on the image will not be displayed in the table. To get all the values selected interactively, you may use
for i = 1 :numSelections
  2 Comments
Jemima Pulipati
Jemima Pulipati on 25 Nov 2020
Hello,
A uitable can accept a 'figure' as a parent container.
Here is the modified code using a 'figure'
image = imread('peppers.png');
P = impixel(image) ;
% Specifying a parent container for uitable
f = figure;
Table = uitable(f,'Units','normalized','Position',[.0 .1 1 .6]);
Table.ColumnName = {'Name','RGB','Color'};
Table.ColumnEditable = [true false false];
Table.RowName = 'numbered';
[numSelections,numCols] = size(P);
% Pre allocating the array for speed
cellArray = cell(numSelections-1,3);
for i = 1 :numSelections-1
% storing the values in a cell array
% converting the string to a char while storing in a cell array
cellArray(i,:) = {char("Label "+num2str(i)), P(i,1), char("Color "+num2str(i))};
end
Table.Data = cellArray;
NOTE: Clearing the workspace would help incase of any errors while running the code

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