Histogram from masked area of grayscale picture
8 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Anders Jensen
am 18 Jun. 2019
Bearbeitet: Steven Lord
am 18 Jun. 2019
Hello!
I want to make a histogram from masked area of a grayscale picture. I've tried this:
maskedImage = bsxfun(@times, grayImage, cast(mask, 'like', grayImage));
histogram(maskedImage(mask), 256, 'EdgeColor', 'none')
But it keeps saying: "Array indices must be positive integers or logical values". There are no negative integers and the mask only contains 0 and 1.
Hope you can help! :-)
0 Kommentare
Akzeptierte Antwort
Steven Lord
am 18 Jun. 2019
Bearbeitet: Steven Lord
am 18 Jun. 2019
When performing indexing, there is a difference between a logical array and a double array containing only 0 and 1. The former works and performs logical indexing, the latter does not work and throws an error because there's no such thing as element 0, row 0, column 0, page 0, etc. of an array in MATLAB.
x = 1:10
L = mod(x, 2) == 0
D = double(L)
onlyEvens1 = x(L) % Works
onlyEvens2 = x(D) % Errors
If mask is a double array containing just 0's and 1's you'll need to convert it into a logical array to use it for indexing. The easiest way to do this is to call the logical function on it.
L2 = logical(D)
isequal(L, L2) % True
onlyEvens3 = x(L2)
0 Kommentare
Weitere Antworten (2)
Image Analyst
am 18 Jun. 2019
Attach a .mat file containing your grayImage and mask.
Alternatively, just do
histogram(grayImage(mask), 256, 'EdgeColor', 'none')
0 Kommentare
Siehe auch
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!