How to imagesc display the image size to keep the size of the original matrix

Question

data is a 512-by-512 matrix, visualized by imagesc, but the original 512-by-512 size cannot be saved, and the image size can only be saved as 800-by-800 by setting the following.

data = rand(512,512);
x = [0 0];
y = [512 512];
figure('position',[200,200,512,512]);
% image(log10(data(1:64,1:64)),'CDataMapping','scaled');
% figure;
imagesc(x,y,log10(data));
axis image;
axis off 
axis equal
axis square
truesize([512 512])
% set(gca,'XTick',[])
% set(gca,'YTick',[])
set (gcf,'Position',[100,100,512,512]);
% truesize(fig,[512 512]);
set(gca,'Position',[0 0 1 1])
axis normal;
saveas(gca,strcat('tumor','.jpg'))
print -djpeg99 'foo.jpg'

Answer 1

imwrite uses the data you input as the pixel values to generate an image of the specified size.

This is an example of a 512-by-512 grayscale image:

data = rand(512, 512);
imwrite(data, 'foo.jpg');

If you want to produce a colour image, you need to input a 3-channel matrix, for example imwrite(rand(512, 512, 3), 'bar.jpg').

The (colour) encoding is otherwise specified in the documentation.