How can the image be like this?

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mayy noensai
mayy noensai on 24 Apr 2022
Answered: Image Analyst on 24 Apr 2022
Hi, I'm a newbie and need help. I want my pictures to focus on vegetables. and the back is a black background that is the same size as the original image. Can you help me? how do writing code
thanks for the help really appreciate it

Answers (2)

DGM
DGM on 24 Apr 2022
Edited: DGM on 24 Apr 2022
This is one way:
A = imread('peppers.png');
imshow(A)
B = zeros(size(A),class(A)); % black image
B(100:250,200:350,:) = A(100:250,200:350,:); % copy ROI from original image
imshow(B)

Image Analyst
Image Analyst on 24 Apr 2022
Use the Color Thresholder App on the Apps tab of the tool ribbon. See if this is what you really want:
% Demo by Image Analyst, April, 2022.
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clearvars;
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
fprintf('Beginning to run %s.m ...\n', mfilename);
%-----------------------------------------------------------------------------------------------------------------------------------
% Read in image.
folder = [];
baseFileName = 'food.jpeg';
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~isfile(fullFileName)
% The file doesn't exist -- didn't find it there in that folder.
% Check the entire search path (other folders) for the file by stripping off the folder.
fullFileNameOnSearchPath = baseFileName; % No path this time.
if ~exist(fullFileNameOnSearchPath, 'file')
% Still didn't find it. Alert user.
errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
uiwait(warndlg(errorMessage));
return;
end
fullFileName = fullFileNameOnSearchPath;
end
rgbImage = imread(fullFileName);
[rows, columns, numberOfColorChannels] = size(rgbImage)
% Crop away other stuff in the screenshot to get the image along.
rgbImage = rgbImage(400:1800, 200:972,:);
% Display the image.
subplot(2, 2, 1);
imshow(rgbImage, []);
axis('on', 'image');
impixelinfo;
caption = sprintf('RGB Image : "%s"', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Set up figure properties:
% Enlarge figure to full screen.
hFig1 = gcf;
hFig1.Units = 'Normalized';
hFig1.WindowState = 'maximized';
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
hFig1.Name = 'Demo by Image Analyst';
%--------------------------------------------------------------------------------------------------------
% Segment (mask) the image.
[mask,maskedRGBImage] = createMask(rgbImage);
% Display the image.
subplot(2, 2, 2);
imshow(mask, []);
axis('on', 'image');
impixelinfo;
title('Initial Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Need to fix the mask.
mask = imfill(mask, 'holes'); % Fill holes in blobs.
mask = bwareafilt(mask, 1); % Take largest blob.
% Display the image.
subplot(2, 2, 3);
imshow(mask, []);
axis('on', 'image');
impixelinfo;
title('Final Mask', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Construct new masked RGB image with new mask
% Mask the image using bsxfun() function to multiply the mask by each channel individually. Works for gray scale as well as RGB Color images.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));
% Display the image.
subplot(2, 2, 4);
imshow(maskedRgbImage, []);
axis('on', 'image');
impixelinfo;
title('Masked Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
%=======================================================================================================
% Color Thresholder generated code.
function [BW,maskedRGBImage] = createMask(RGB)
%createMask Threshold RGB image using auto-generated code from colorThresholder app.
% [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using
% auto-generated code from the colorThresholder app. The colorspace and
% range for each channel of the colorspace were set within the app. The
% segmentation mask is returned in BW, and a composite of the mask and
% original RGB images is returned in maskedRGBImage.
% Auto-generated by colorThresholder app on 24-Apr-2022
%------------------------------------------------------
% Convert RGB image to chosen color space
I = rgb2hsv(RGB);
% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.054;
channel1Max = 0.311;
% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.390;
channel2Max = 1.000;
% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.374;
channel3Max = 1.000;
% Create mask based on chosen histogram thresholds
sliderBW = (I(:,:,1) >= channel1Min ) & (I(:,:,1) <= channel1Max) & ...
(I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...
(I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);
BW = sliderBW;
% Initialize output masked image based on input image.
maskedRGBImage = RGB;
% Set background pixels where BW is false to zero.
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;
end

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