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Transform without perspective distortion (?)

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Tiago Cotrim
Transform without perspective distortion (?)
on Jul 8, 2013 at 9:24:54 pm

I'm a fairly advanced PS user and maybe for the first time ever I'm trying to do something I can't find out how to or anything about it, which is to "distort" an image by squeezing one of its sides, but the only way I know how to do it is by transforming it and using one of the perspective tools. It's close to what I want, except I don't want the image to be distorted to create the perspective effect. It's pretty complicating to put it into words, I hope the attached picture explains better.



Just to make it as clear as I can, I started out with a checkered image (A), and just regularly transformed it (Perspective). Notice how the "X axis" gets streched out to create a depth effect. It's normally what I'd want, but THIS TIME I'm trying to achieve what I tried to picture on C, without the X axis distortion. The way I did that was to warp it and manually move the handles to try to make it as straight as I could. It's not too bad, but it took me about 5 minutes to achieve this result, which is far from perfect and far from practical. Am I making myself clear?

Does anyone know of any way to do this "the right way"?


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Jeff Hinkle
Re: Transform without perspective distortion (?)
on Jul 10, 2013 at 3:03:10 pm

I think I understand what you're getting at. Couple possible suggestions.

1. Depending on how much actual distortion you want, you can make a 3d postcard out of your object and rotate it to taste. You won't get quite the severe right-side compression you show, but there won't be any X-axis distortion.

2. Probably closer to what you want, but you do need some extra pixels top and bottom you're willing to lose. Use the Perspective Crop tool, then squeeze in the corners on the LEFT side of the image. Apply the crop and Photoshop will adjust things to keep overall ratio of the internal pixels the same. Then use a mask to clip away the top and bottom of the image to match your perspective. Not automatic, but should be faster and more precise than warping by hand.

http://images.creativecow.net/99851/perspective.jpg

---
It is easier to destroy than to create.
More fun, too.


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Darby Edelen
Re: Transform without perspective distortion (?)
on Jul 10, 2013 at 10:28:50 pm

Also it appears that expanding the left side instead of shrinking the right side will not cause as much distortion. You can scale the entire image down in the same transformation to get the size you want. Net effect would be similar to shrinking the right side in perspective but without nearly as much distortion.

Darby Edelen


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Tiago Cotrim
Re: Transform without perspective distortion (?)
on Jul 11, 2013 at 12:05:27 am

You're right, I never would have tried that, since it doesn't make any logical sense! :P

It still doesn't quite solve my issue, though... I can't believe there's no "normal" way of doing that, there should just be an option when you CTRL+T like "don't distort my picture, please".

But I really appreciate your effort, thank you so much. :)


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Darby Edelen
Re: Transform without perspective distortion (?)
on Jul 12, 2013 at 3:18:37 pm

Expanding or contracting one side of a rectangle is going to necessarily introduce distortion unless the software has a way to scale the contents of the rectangle adaptively across the rectangle to reduce horizontal distortion without scaling the bounds of the rectangle. I would guess that this is not as trivial as one might think.

Darby Edelen


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Tiago Cotrim
Re: Transform without perspective distortion (?)
on Jul 12, 2013 at 4:57:19 pm

Actually Photoshop purpously added an algorithm to do this distortion so that you can easily "fit" images into right perspectives and get an accurate result (such as changing the content on a photo of a billboard). Simpler image editors don't have that, and I managed to get the result I wanted with a few lines of codes on Construct. There must be a way to do it on Photoshop...


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Jeff Hinkle
Re: Transform without perspective distortion (?)
on Jul 12, 2013 at 5:19:39 pm

Can you post a shot of the final result you did want? I'm curious if I was even picturing the right thing.

---
It is easier to destroy than to create.
More fun, too.


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Tiago Cotrim
Re: Transform without perspective distortion (?)
on Jul 10, 2013 at 11:48:55 pm

Your second idea was pretty creative. :)
But all of them still give me the perspective depth I don't want... your attached file still ends up with the last columns less than half the width of the first.

Thank you so much for your input and effort, I really appreciate it.


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