Correcting Verticals in PS
 

A quick and dirty guide to correcting verticals as requested

I am using Photoshop CS and I think it is the same in PS 7.

I have used Don's image as this is a simple example to start with.

1) Open the file in Photoshop

2) F7 or Window menu select layers option

3) Go to layers window and double click on Background (note this is locked). This will open a new layer dialogue and click on OK. Background has now has become Layer 0. This enables step 5.

4) View menu select new Guide and position a new vertical guide over the area where you want to check and adjust the vertical.

5) Edit menu -> Transform select Perspective option

6) This will provide anchor points around the edge of the image for you to adjust

7) Click on the top right hand point and pull to the right until the image vertical lines up with the guide.

8) Hit return key to make the correction

9) Layer Menu and select Flatten Image option

10) Save as new image

Image 1 shows the layer widow and a vertical Guide added (cyan line).
Image 2 shows 2 vertical Guides and adjusting the perspective tool
Image 3 shows final image.

Use of the rotate, skew and distort tools are very similiar in their action.

I note in Don's image there is a slight barrel distortion maybe we can look at correcting that at a later date.

A quicker way, using a single step, is to "select all" on the original image and use the distort tool rather than perspective, this allows you correct both verical and lateral perspective at the same time. In CS2 barrel, pincushion, lateral and vertical perspective, as well as chromatic aberration can all be corrected using the single "lens distortion" tool. this tool aslo applies the alignment grid automatically.

Thanks for the tip Windy - The method I used I was shown for PS 7 maybe somebody with PS7 can confirm if this short cut works for PS7.

Yes I agree about using the distort tool to do both vertical and horizontal perspective at the same time. I used this on Nogbad's image.
To start with it maybe easier to start learning the perspective tool and move onto the distort tool.

I've not managed to get my hands on CS2 yet - I am hoping my work will buy an upgrade :)

Top notch Rob,

Lens is prosumer. Have not got a Nikkor that wide. I tend not to stretch this type of kit, but I gave a quick example of the effect.

Very impressed Rob. Flicking between your straightened and orig straight on, it certainly has not upset any other lines.

Don

If you're into short cuts, even quicker is ctrl+A,ctrl+' ,edit-transform-distort. From what I remember it's the same in PS7, the older I get the slower I am to learn, but my memory is still OK (I think):-)

ctrl+A =select all
ctrl+' puts on a full grid

Even quicker - don't tilt your camera upwards or downwards in the first place ;)

Just had a quick play and found this works in PS Elements as well. However unless someone can advise otherwise I can't find an automatic grid overlay. The best I can do is put rulers round the edge and draw one in a separate layer which is workable but tedious.

I only have experience of elements 4 but in this you go to the view menu and select show grid,you'll get an overlay on the picture. In Photoshop the other option is to use guidelines rather than grid, here you simply click onto the ruler and drag a line, either horizontal or vertical to where you want it. I doesn't seem to work in elements, but I might be missing something.

After nearly 40 years in photography I can still manage to get sloping horizons. I think my brain is lopsided:-)

Doh! :rolleyes: Guessed it ought to be in Elements 2 somewhere. Thanks Windy.

Yes, ditto! I reckon that grid overlay that Nikon put in their focus screens (was it the F80?) was one of the better developments in SLR design. Some systems have a grid screen as an option but the idea of just calling it up when you need it rather than having to change screens was an inspired idea.

Thanks to everyone who has contributed to this thread, it's been very helpful.

I saw a building with a wonderful mural on the side which had to be taken in 2 bites of the cherry. Not having packed my rocket boots, I was not able to take the pictures from anything other than ground level. A combination of the need to use a fairly wide angle setting (limited space in street), ground angle shooting, and the warping introduced by stitching pictures together, meant I had some serious distortion to correct. It didn't help that the building isn't square on the front to begin with.

Original joiner and the best corrected image I can come up with are attached. The tools can only correct so much. Until they make rocket boots in a more portable size, you have to live with some warping!

Duncan.

I downloaded a demo lens correction plugin for PS from Power Retouche to see if it would do a better job. It was the first one I bumped into after doing a google - look fairly good lots of other tools - I must admit I did not stay long enough to see how much it was - LOL. As you say Duncan it is a mare of a building.

I spent a few minutes with it to reduce the barrel distortion and then the normal PS tools. I think it looks a tad better.

I wanted to see how effective the plugin was as the only wide angle lens I have is the Canon Kit lens 18-55 which distorts like hell. The 24-70 L is not really wide enough for some scenes.

OMG I've just noticed - you age quickly on this forum. When I joined a few weeks ago I started as a junior and now I am a Senior.

Well Duncan you've driven me nuts !!

I am not a digital darkroomer but I thought I ought to try and learn something. I am using PSP7 with an occasional dip into 8.

Rob yours is a super effort. I've spent nearly an hour on this, and find that the more the top is corrected the worse the bottom gets. I attach mine uncropped, so the effect is seen. I tried perspective control first then barrel distortion. Even tried fisheye as I thought that may push in the centre to bring forward the bottom. No luck. I have added a dotted line along the bottom to show how it falls away.

I'm going to bed now before this cracks me up !!!!!!

Don

PS Wonderfull building.

Don I think the secret is to get CS2 asWindy says this has I nice lens tool. I was getting into the same mess as you. Thats why I went hunting for a PS plugin for Lens correction. I notice that another software was mentioned in the other thread for lens correction. PS7 and 8 itself does not have the right sort of concave adjustment to correct the barrel distortion.

Hmmm, yes, 'tis a 'mare of a building, isn't it? You can see why I asked for advice now, can't you? :)

You've all done very well. (Thank you Mr. Grace. That'll be completely lost on many). I did my efforts using CS2 lens correction tool, using a combination of correcting the perspective and barrel distortion. As Don says, the more the top is corrected, the worse the bottom gets.

I woke up this morning (at about 5:00 am!) with the idea of correcting the perspective/distortion on each of the two parts of the joiner before stitching them together. There is actually very little perspective distortion on the bottom picture, as you'd expect, so applying the major correction to the top before stitching should stop the bottom going so squiffy. I'll let you know how I get on. Probably about midnight!

Duncan.

P.S. Rob, I had noticed your "birthday" too!

Duncan I tried a vertical cut without luck so possibly a horizontal with your joiner expertise may do it.

Try as I might I cold not get the bottom to line up like Rob. All good fun though.

Don

OK, here's the best I can manage. Gave up on correcting the distortions on the "joiner" as the distortion in the top and bottom halves was just far too different between the two parents. I've gone back to the single image I took, and just removed the distortion as best as I can from that. Still a sod of a building though. Nothing is as square as it seems!

Thanks to all for your advice on how to do this, it's been most helpful.

Regards,

Duncan

Ducan

A Photoshop CS2 tutorial on lens and perspective correction.
http://public.cps.canon-europe.com/I...rial/index.asp

I did not get to look at it yet as our web connection is slow this afternoon.