how to crop the image from the green screen

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Nikhil Gulati
Nikhil Gulati il 10 Mar 2020
Risposto: Image Analyst il 28 Ott 2024
the background of the image will be green but i want to detect the white rectange inside and crop the image removing the green screen

Risposte (3)

Image Analyst
Image Analyst il 10 Mar 2020
Use the Color Thresholder app on the Apps tab of the tool ribbon.

Gautam
Gautam il 24 Ott 2024
You can crop out the green portion by thresholding or quantizing the image based on colours.
Here's a code that uses K-means clustering to quantize the image and crops it
img = imread('image.jpeg');
numColors = 3;
L = imsegkmeans(img,numColors);
mask = mat2gray(L) > 0;
[rows, cols] = find(mask);
topRow = min(rows);
bottomRow = max(rows);
leftCol = min(cols);
rightCol = max(cols);
croppedImg = img(topRow:bottomRow, leftCol:rightCol, :);
imshow(croppedImg);

Image Analyst
Image Analyst il 28 Ott 2024
Try this:
% Demo by Image Analyst
% Initialization steps:
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
markerSize = 20;
%--------------------------------------------------------------------------------------------------------
% READ IN TEST IMAGE
folder = [];
baseFileName = 'green Background.jpeg';
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
% 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
end
rgbImage = imread(fullFileName);
%--------------------------------------------------------------------------------------------------------
% Display the image.
subplot(2, 2, 1);
imshow(rgbImage, []);
impixelinfo;
axis('on', 'image');
title('Original RGB Image', 'FontSize', fontSize, 'Interpreter', 'None');
% Update the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(rgbImage)
% Maximize window.
g = gcf;
g.WindowState = 'maximized';
g.Name = 'Demo by Image Analyst';
g.NumberTitle = 'off';
drawnow;
%--------------------------------------------------------------------------------------------
% MASK THE IMAGE.
[mask,maskedRgbImage] = createMask(rgbImage);
% mask = bwconvhull(mask, 'objects');
mask = imfill(mask, 'holes');
% Take largest blob (in case there are small noise blobs).
mask = bwareafilt(mask, 1);
% Show the mask image.
subplot(2, 2, 2);
imshow(mask)
impixelinfo;
axis('on', 'image');
caption = sprintf('Final Mask Image');
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
% Mask the image with the new mask
% Mask image by multiplying each channel by the mask.
maskedRgbImage = rgbImage .* cast(mask, 'like', rgbImage); % R2016b or later. Works for gray scale as well as RGB Color images.
%--------------------------------------------------------------------------------------------
% FIND THE CROPPING BOX.
props = regionprops(mask, 'BoundingBox');
maskedRgbImage = imcrop(maskedRgbImage, props.BoundingBox);
% Show the masked and cropped image.
subplot(2, 2, 3:4);
imshow(maskedRgbImage)
impixelinfo;
axis('on', 'image');
caption = sprintf('Final Image');
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
%===============================================================================================
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 26-Oct-2024
%------------------------------------------------------
% Convert RGB image to chosen color space
I = rgb2hsv(RGB);
% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.465;
channel1Max = 0.303;
% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.000;
channel2Max = 1.000;
% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.539;
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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R2019b

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