I have an satellite image and I want to extract the information from ROI of image?

I have an satellite image and I want to extract the information from the red portion of the image. How can I obtain the information from the red portion of the image?

I have attached the image and the portion of image from where I want to extract the information

Answer 1

[Kevin Holly]

Note, I used Computer Vision Toolbox below.

Capture_img = imread('Capture.jpg');
Picture1_img = imread('Picture1.png');
imshow(Capture_img)

imshow(Picture1_img)

size(Picture1_img)

ans = 1×3

677 692 3

size(Capture_img)

ans = 1×3

627 663 3

Using the Registration Estimator app to make sure images are co-registered:

[NewPicture1_img] = registerImages(Picture1_img,Capture_img)

NewPicture1_img = struct with fields:
     FixedMatchedFeatures: [220×1 SURFPoints]
    MovingMatchedFeatures: [220×1 SURFPoints]
           Transformation: [1×1 projective2d]
          RegisteredImage: [627×663×3 uint8]
            SpatialRefObj: [1×1 imref2d]

imshow(NewPicture1_img.RegisteredImage)

Picture1_img=NewPicture1_img.RegisteredImage;
imshow(Picture1_img(:,:,1))

imshow(Picture1_img(:,:,1)>225&Picture1_img(:,:,2)==0)% When red slice intensity values are greater than 225 and green slice intensity values are equal to 0.

% Convert logical matrix into 8-bit image then multiply by Capture_img
imshow(Capture_img.*uint8(Picture1_img(:,:,1)>225&Picture1_img(:,:,2)==0))

function [MOVINGREG] = registerImages(MOVING,FIXED)
%registerImages  Register grayscale images using auto-generated code from Registration Estimator app.
%  [MOVINGREG] = registerImages(MOVING,FIXED) Register grayscale images
%  MOVING and FIXED using auto-generated code from the Registration
%  Estimator app. The values for all registration parameters were set
%  interactively in the app and result in the registered image stored in the
%  structure array MOVINGREG.

% Auto-generated by registrationEstimator app on 09-Jan-2023
%-----------------------------------------------------------


% Feature-based techniques require license to Computer Vision Toolbox
checkLicense()

% Convert RGB images to grayscale
FIXED = im2gray(FIXED);
MOVINGRGB = MOVING;
MOVING = im2gray(MOVING);

% Default spatial referencing objects
fixedRefObj = imref2d(size(FIXED));
movingRefObj = imref2d(size(MOVING));

% Detect SURF features
fixedPoints = detectSURFFeatures(FIXED,'MetricThreshold',750.000000,'NumOctaves',3,'NumScaleLevels',5);
movingPoints = detectSURFFeatures(MOVING,'MetricThreshold',750.000000,'NumOctaves',3,'NumScaleLevels',5);

% Extract features
[fixedFeatures,fixedValidPoints] = extractFeatures(FIXED,fixedPoints,'Upright',false);
[movingFeatures,movingValidPoints] = extractFeatures(MOVING,movingPoints,'Upright',false);

% Match features
indexPairs = matchFeatures(fixedFeatures,movingFeatures,'MatchThreshold',50.000000,'MaxRatio',0.500000);
fixedMatchedPoints = fixedValidPoints(indexPairs(:,1));
movingMatchedPoints = movingValidPoints(indexPairs(:,2));
MOVINGREG.FixedMatchedFeatures = fixedMatchedPoints;
MOVINGREG.MovingMatchedFeatures = movingMatchedPoints;

% Apply transformation - Results may not be identical between runs because of the randomized nature of the algorithm
tform = estimateGeometricTransform2D(movingMatchedPoints,fixedMatchedPoints,'projective');
MOVINGREG.Transformation = tform;
MOVINGREG.RegisteredImage = imwarp(MOVINGRGB, movingRefObj, tform, 'OutputView', fixedRefObj, 'SmoothEdges', true);

% Store spatial referencing object
MOVINGREG.SpatialRefObj = fixedRefObj;

end

function checkLicense()

% Check for license to Computer Vision Toolbox
CVTStatus = license('test','Video_and_Image_Blockset');
if ~CVTStatus
    error(message('images:imageRegistration:CVTRequired'));
end

end

[Kevin Holly]

If you want the size (e.g. pixel area, major axis length) or other properties of the ROI, you can use regionprops on the binary image, where the ROI has a value of one and all other pixels have a value of zero.