What is the Image -- Rotate -- Automatic deskew action?

[ebergerxn]

I have tried deskew in 1.3.1. I cannot tell what it does. What does this feature under Image/Rotate do?

[cday]

I have tried deskew in 1.3.1. I cannot tell what it does. What does this feature under Image/Rotate do?

The intended action is to straighten the image on the image canvas: for example if an objecte in an image is rotated slightly out of the horizontal. When the image canvas is rotated some new canvas is added as the final image must, of course, be rectangular.

Successful operation depends on the image having a recognisable nominally horizontal (or possibly alternatively vertical?) reference; in a quick test using an image to hand that should have produced a good result, the image produced was disappointing, but possibly in other circumstances the results would be better.

That's my understanding...

[ebergerxn]

Thank you. So it sounds like an automatic version of the rotate feature that is available on rotate menu. However it does not appear it is intended to fix a rectangle that is our of kilter as in a parallelogram?

[cday]

So it sounds like an automatic version of the rotate feature that is available on rotate menu. However it does not appear it is intended to fix a rectangle that is our of kilter as in a parallelogram?

That depends on what you want to do, you might need to rotate an image level, or rotate an object away from the horizontal, for example.

However it does not appear it is intended to fix a rectangle that is our of kilter as in a parallelogram?

Only to rotate an object, not to anticipate how a viewer thinks an object should look! Again, that is my understanding, maybe someone else knows better?.

Searching the forum, the option has evidently been available for some time, at least in XnView Classic, and one use mentioned is to straighten scanned images that are slightly skewed.

[ebergerxn]

thank you

[cday]

See also this new thread Re: Rotate - move 'Automatic Deskew' option to the top.