How i can crop image with bw roipoly and how to display?

clc;clear;close all;

a = imread('Capture1.png','png'); figure, imshow(a), title(' bearing pompa Tanggal 9 Agustus'); I=uint8(a); h = impoly; position = wait(h); BW = createMask(h); out = gray .* uint8(BW); imshow(out);

why always display like this when i was done with decission of my cropping position? anyone can help me to solve this problem?

Thank you so much :)

Answer 1

[Takuji Fukumoto]

If you want to show the segmented image, please try this after creating mask.

out = rgb2gray(I);
out(~BW) =0;
imshow(out);