extracting biggest square from a rotated image

[manit]

ok .
Here is the original 512x512 image -> https://ibb.co/cneSfz
Then I ran this command
convert f0001_01.png -rotate 15 -set option:leg "%[fx:512/(cos(15*(pi/180))+sin(15*(pi/180)))]" -set option:distort:viewport "%[leg]x%[leg]" \( -clone 0 -distort srt 0 \) -gravity center +swap -composite output.png
where f0001_01.png is the above original image.

output.png looked like this -> https://ibb.co/dBcxfz .
Notice that there is a triangle in bottom left corner .

[manit]

I am beginning to think that it works as follows
convert f0001_01.png -rotate -15 rotated.png
Then
convert rotated.png -rotate 15 -set option:leg "%[fx:512/(cos(15*(pi/180))+sin(15*(pi/180)))]" -set option:distort:viewport "%[leg]x%[leg]" \( -clone 0 -distort srt 0 \) -gravity center +swap -composite output-with-rotated-input.png

But in such cases also i have observed a white triangle in corner of image .

Can you give a working example ?

Thanks .

[GeeMack]

But in such cases also i have observed a white triangle in corner of image .

The command you've been using works perfectly. The sample image you provided has a 32 pixel high strip of white along the bottom edge. That's what makes the white triangle in your output.

[manit]

But in such cases also i have observed a white triangle in corner of image .

The command you've been using works perfectly. The sample image you provided has a 32 pixel high strip of white along the bottom edge. That's what makes the white triangle in your output.

ok .