What does using empty brackets [] in Imshow accomplish?

Hi, I'm working through a piece of example code that I found online. In the code an image file type called fdf is being parsed and the data pulled out so that it can be displayed in matlab using imshow. After the processing is done the final bit of code is:

figure;
imshow(img2,[])
colormap(gray);
axis image;
axis off;

I can't figure out what the empty [] does on the imshow line. The documentation seems to indicate that the only use of square brackets in the imshow method is to give a display range, so what is indicated by empty brackets? I've tried replacing it with [0 0] to no avail.

Removing the brackets or replacing it with 0's results in a black image whereas leaving them in place gives the gray scale image i'm expecting.

Thanks for any help,

David

Answer 1

[Walter Roberson]

[] as the display range means to use min() of the data and max() of the data as the display range -- so the data that is actually present is mapped to the full available colormap. Same thing as if you had used imagesc(img2)

[Image Analyst]

Except that imagesc() applies a funky colormap (that you have to undo with a call to colormap(gray(256)) while imshow() doesn't apply a colormap.

[David]

Thanks so much!