# Thread: Tutorial: Rotating Skewed Images Accurately

1. ## Tutorial: Rotating Skewed Images Accurately

This tutorial is for the benefit of members who routinely ask how to correct skewed images. Enjoy!

Acknowledgement: The image used here was taken from ClubSNAP member hong from this thread for lack of any suitable image in my library. If hong has any objection, I will remove this image and try to get another one.

This is the original image as posted:-

2. We will use the Measure tool to accurately determine the angle for correction. The Measure tool is found here:-

Using the Measure tool, we then measure a known good horizontal or vertical line in the image. In this example, I measured the vertical side of the HDB block as shown:-

Next we use the Arbitrary Rotate menu command to do the actual rotation. The menu can be found here:-

which will bring up this dialog box with the angle and direction of rotation already entered, and all you have to do is to hit ENTER:-

3. The result of the rotation will be a canvas which shows an image with corrected verticals, but with white spaces where the canvas has been "expanded" in the rotation process:-

We then do a crop to get the final image as shown here -

4. To confirm that the image is indeed correctly aligned, I would suggest turning on the grid ie View > Show Grid.

This is especially so if you want to correct converging or diverging verticals as well, using Distort.

5. Tutorial

6. This is great!
Thus far, I've always been using "agar-ation"!
Very much thanks!

How about a tutorial on correcting converging or diverging verticals? I'm quite sure many users (myself inclusive) will benefit from it.

Have another question which I hope someone can help.
After doing a rotation, let's say I wanna crop the picture to a particular size of exactly x times y pixels, how do I actually go about doing it? At the moment, what I do is "agar-ation" again, just select, resize down and hope for the best...

Thank you very much!

7. ## Perspective Correction

Turn on rulers, Ctrl-' and place a ruler along all vertical lines and then Ctrl-A, Ctrl-T and drag corner nodes.

8. Originally posted by Fella
Have another question which I hope someone can help.
After doing a rotation, let's say I wanna crop the picture to a particular size of exactly x times y pixels, how do I actually go about doing it? At the moment, what I do is "agar-ation" again, just select, resize down and hope for the best...
This one already done ... *sigh* we all die-die write review no one refer to ... very, very sad ...

Guide to Resizing and Cropping by Darren

shameless self-promotion

9. Originally posted by Darren
This one already done ... *sigh* we all die-die write review no one refer to ... very, very sad ...

Guide to Resizing and Cropping by Darren

shameless self-promotion
My apologies!!
Anyway, it's a life-saver!

10. Actually, this way works but I don't think it's the most efficient. There is another way

11. u can actually ROTATE and CROP at the same time. But u need a steady hand/optical mouse and keyboard to do well.

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