CODEWITHSUNDEEP
imagematlabimage-processing
kankeu fotsing cedric parfait
kankeu fotsing cedric parfait

Reputation: 11

Difficulties with Matlab12b function imshow()

I'm using MATLAB for image processing and I came across a code with the instruction: 

imshow(pixel_labels,[]);

when executed it give a binary image.

I have check the manual of the function on Mathworks.com, the most similar used mode is

imshow(I,[low,high]);

but they don't say a thing about the case where that array is empty ([])

I tried to remove it: 

imshow(pixel_labels);

but all I see is a white board. I would like to know what is happening in the first use case (imshow(pixel_labels,[])), I hope from there I will understand why I get a white board in the last use case.

Upvotes: 1

Views: 300

Answers (1)

Rody Oldenhuis
Rody Oldenhuis

Reputation: 38042

If I type help imshow in MATLAB, the first paragraph reads:

IMSHOW(I,[LOW HIGH]) displays the grayscale image I, specifying the display range for I in [LOW HIGH]. The value LOW (and any value less than LOW) displays as black, the value HIGH (and any value greater than HIGH) displays as white. Values in between are displayed as intermediate shades of gray, using the default number of gray levels. If you use an empty matrix ([]) for [LOW HIGH], IMSHOW uses [min(I(:)) max(I(:))]; that is, the minimum value in I is displayed as black, and the maximum value is displayed as white.

so [] is simply shorthand for [min(pixel_labels(:)) max(pixel_labels(:))].

Upvotes: 2

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