One image 2 diferent colors ,

I have one image with a circle, outside the circunference the color are black inside the circle the color before convert to grayscale, is gray, how can apply after normalize de image apply a mask who convert a the background in same color (gray). https://www.dropbox.com/sc/zfp80poi11m8q55/lnRX67BT4L exemple image A and B

Answer 1

[Image Analyst]

It looks like B was simply the convolution of A with a high pass filter, like the Laplacian or dog filter. Do you want to do that or you simply want the black surround to be gray?

[roudabe]

Would you please let me now how can I use Laplacian high pass filter on images?

[Image Analyst]

kernel = [-1,-1,-1;-1,8,-1;-1,-1,-1];
output = conv2(double(inputImage), kernel, 'same');
imshow(output, []);

Answer 2

[Biza Ferreira]

I Removing the background image was obtained by subtracting the original version of this image strongly smoothed (result of filtering with a filter medium sized relatively high). The intensities of the image resulting from the subtraction were subsequently reescaladas for the full range of image intensities (0-255).

if true
 fontSize= 12;
A = imread('imagens/03_test.tif');
%B = rgb2gray(A);%original a P&B
ft_high=[0 -1/4 0; -1/4 2 -1/4; 0 -1/4 0];
h = fspecial('average', [5 5]);
filtered= imfilter(A,h,'replicate');
filtered1= imfilter(A,ft_high,'replicate');
Subtract=filtered-A;
Subtract1=A-filtered1;
B = rgb2gray(Subtract1);%original a P&B
J = imadjust(B);
figure;
subplot(2,2,1); 
imshow(A),
title('Original Image Color', 'FontSize', fontSize);
subplot(2,2,2);
imshow(filtered);
title('Filter Image Median', 'FontSize', fontSize);
subplot(2,2,3);
imshow(filtered1);
title('Filter Image Median with High', 'FontSize', fontSize);
subplot(2,2,4);
imshow(Subtract);

end

[Image Analyst]

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