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Image ProcessingUsing Distortion Adjustment to Square Up an Image

Post-processing: Editing techniques, software, hardware and other resources. Chemical or digital.
From simple corrections to multi-layered edits, actions, tone mapping and more.
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St3v3M
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Re: Using Distortion Adjustment to Square Up an Image

Postby St3v3M » Thu Jun 01, 2017 1:25 am

Charles Haacker wrote:... You've proved that it can be done and I think it's wonderful! :thumbup: (OK)

To try the impossible is to have done more than most, but to try the impossible and win, now that's something special! S-
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Re: Using Distortion Adjustment to Square Up an Image

Postby Ceropegia » Thu Jun 01, 2017 12:30 pm

Charles Haacker wrote:Martha, I think that's a terrific job! I can see at a glance at the top of the original that monster support column almost dead-center, plus close to the mural (ya gotta wonder why somebody decided to put a gorgeous work of art there but I guess it hadda go someplace). I cannot perceive any major distortion, especially at the right end where I would expect it to be most apparent. I can see a faint grid of lines (tiles, perhaps?) that is perfectly aligned vertically and horizontally. The colors are vibrant and if not accurate who (frankly) cares? I have done this myself but never on this scale, assuming going in that it wouldn't work, a bridge too far. You've proved that it can be done and I think it's wonderful! :thumbup: (OK)

Thanks!
Actually that giant column is left of center with another giant column to the right which are close enough that I think the only way to get a complete head on image would be with a super wide angle lens. The distortion that seems apparent to me is on the left side where I think the figures are thinner than they should be. Makes me wonder if it would have been less noticeable if I had stretched the image from both sides, which I'm not sure I did, but I'm not inclined to revisit it. The grid lines are, indeed, tiles or something similar on the building. FYI, the building is scheduled to be demolished as part of a civic center revitalization plan, but probably not until about 2032. Other murals by the same artist have been rescued when their buildings were demolished. I hope an effort will be made to save this one. Apparently, he painted another mural at an entrance on the other side of the building, but we did not walk that way so missed it.
Last edited by Ceropegia on Sat Jun 03, 2017 1:58 am, edited 1 time in total.

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Re: Using Distortion Adjustment to Square Up an Image

Postby Ceropegia » Thu Jun 01, 2017 12:41 pm

St3v3M wrote:
Charles Haacker wrote:... You've proved that it can be done and I think it's wonderful! :thumbup: (OK)

To try the impossible is to have done more than most, but to try the impossible and win, now that's something special! S-

Thanks again! But it really wasn't impossible to begin with, just took some great editing tools and a little perseverance.

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Re: Using Distortion Adjustment to Square Up an Image

Postby mikec » Thu Jun 01, 2017 2:17 pm

Agree with all the comments. Great job. Could you explain to this novice what you meant by expanding the canvas?
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Re: Using Distortion Adjustment to Square Up an Image

Postby Ceropegia » Thu Jun 01, 2017 9:14 pm

mikec wrote:Agree with all the comments. Great job. Could you explain to this novice what you meant by expanding the canvas?

In Photoshop Elements 12 (PSE 12), the editor I used, an image being edited rests on a background layer which is in essence the canvas size. Note - this background is what shows through if an eraser tool is used to erase part of an image. The canvas size stays the same size as the image even when the image size is changed, say by decreasing its resolution. However, when an image is transformed using one of the transforming tools that skew it or distort it in such a way that the image is stretched out, parts of the image may extend beyond the fixed borders of the canvas. Since PSE 12 does not change the canvas size to accommodate the parts stretched out beyond the borders of the canvas, those parts of the image will be cut off. To avoid that happening, PSE 12 has a tool for resizing the canvas to make it large enough (expanded) so that the image when transformed will remain "on the canvas" and no parts will be lost. BTW, many earlier versions of PSE have the same tools. I hope this explanation was not too convoluted. Perhaps someone else can explain it better.

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Re: Using Distortion Adjustment to Square Up an Image

Postby mikec » Fri Jun 02, 2017 2:59 pm

Thanks Martha, will have to experiment with your explanation.
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Re: Using Distortion Adjustment to Square Up an Image

Postby John N » Tue Nov 07, 2017 9:37 am

I use PSE10 to straighten all sorts of things from horizons to perspectives. Normally this means just pulling the top out a bit to correct a tall building or resolve converging trees. But here you've got a 3D problem as well in that the shot is running away from you.
Trees and Nature seem to be fairly easy to deal with, Architecture somewhat more difficult. On a few occasions, I've gone so far as to place a plastic ruler on the screen and work out the ratio and used that ratio to rework my perspective. It's not bang on, but I find if I'm struggling a bit it gives a helping hand. You might want to try similar.

Looking at your image and in particular, the fish at the top left corner and the shield in the middle, I'd say your image needs lengthening a little.

But is a decent job and one that I would have been proud to have done!


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