complement a ROI region of an image

Hi everybody. I have used matlab answers in order to use imellipse to crop an image (I have attached the original and cropped images). it works great for my data. Now, I want to complement only the ROI region (make black intensities white and white ones black) and keep the background black as well. Is there any solution for that?

% 1) Open the image file as a workspace variable:
img = rgb2gray(imread('4-chamber view41.jpg'));
% 2) Display the image and store its handle:
h_im = imshow(img);
% 3) Create an ellipse defining a ROI:
e = imellipse(gca,[265 160 273 381]);
% 4) Create a mask from the ellipse:
BW = createMask(e,h_im);
% 4a) (For color images only) Augment the mask to three channels:
BW(:,:,2) = BW;
BW(:,:,3) = BW(:,:,1);
% 5) Use logical indexing to set area outside of ROI to zero:
ROI = img;
ROI(BW == 0) = 0;
% 6) Display extracted portion:
figure, imshow(ROI);
BR

Answer 1

[Image Analyst]

Try this:

img = 255 - img; % Invert gray levels.
img(~BW) = 0;  % Make sure background stays black.

[talayeh ghodsi]

sorry i have some errors, maybe i put it in wrong place in the code

is it possible for you to put it in the right place in the code?

thanks

[Image Analyst]

Did you try this?

% 1) Open the image file as a workspace variable:
img = rgb2gray(imread('4-chamber view41.jpg'));
% 2) Display the image and store its handle:
subplot(1, 2, 1);
h_im = imshow(img);
% 3) Create an ellipse defining a ROI:
e = imellipse(gca,[265 160 273 381]);
% 4) Create a mask from the ellipse:
BW = createMask(e,h_im);
img = 255 - img; % Invert gray levels.
img(~BW) = 0;  % Make sure background stays black.
subplot(1, 2, 2);
imshow(img);

[talayeh ghodsi]

thanks a lot

[talayeh ghodsi]

sorry and do you know how can i rotate only the complemented region (ROI)? for example rotate your right image 45degree clockwise?

[Image Analyst]

rotatedImage = imrotate(img, 45); % Or -45.

[talayeh ghodsi]

thanks a lot