Converging Verticals basically means that lines like the sides of buildings which are perpendicular to th ground look in a picture as though they are bending inwards. Now, let me say straight away this is an entirely natural phenomenon and is not always a problem. However, when very close to a building and using a very wide lens, the convergence can become overly exaggerated and look rather strange.
The good news is this is a very simple problem to fix in Photoshop and other editing packes. I am showing screenshots from Photoshop CS3 but any version of Photoshop will let you do this. I am going to give you not one but two ways to solve the same problem. Choose whichever you find easiest and whichever works best at the time.
Ok, here is a picture that has the problem we are talking about. It's a rubbish picture so ignore the lighting and things, I chose it only to show the problem and how to cure it....
You can see how much the lines of the sides of the Town Hall in Keswick are converging strongly. I am going to correct them to vertical but remember, in order to keep them looking natural, you might be best going to near but not exactly vertical. It will depend on the picture you are correcting.
Before you start:
Whenever you are doing 'destructive editing', always work on a duplicate layer so that you can always g back and start again if you go badly wrong.
To do this, simply Press Ctrl + J (in Photoshop) and you will instantly see in your layers pallet that you now have two identical layers. Work on the top layer and if anything goes badly wrong, just delete that layer, make a new copy of the original layer and start again
Method 1: Distort Tool
Assuming you have made your duplicate layer and have the top layer selected, let's move on. We are going to use the Distort Tool. You can find this by going to: EDIT > TRANSFORM > DISTORT (See graphic below)
Ok, Assuming you are viewing the picture large enough to fit the screen, we want to zoom out slightly so that we have 'canvas' area to work with around the picture. To make your picture fit the screen, just double-click on the hand icon on your tool bar.
To zoom out, just hold Alt+Spacebar and click on the picture. If you go too far and want to zoom in, just hold Ctrl+spacebar and click
Now, with the distort tool selected, you will see the entire icture has got 'handles' and a frame around it. Handles are the four little boxes at the corners and the four boxes in the middle of each side. All eight handles can be adjusted independently. If you want to try it, just click and drag one anywhere you like. To undo that, hit Ctrl+Z.
We are going to drag the top corner handles outwards and as you do you will see in real time the picture 'distorting' so you can get the lines to vertical and then release the mouse button. Remember you can do this as many times as you want and I recommend using small corrections at first as when you pull one side it will affect the whole picture, including the other side, so keep an eye on what is happening.
If you find you have not got enough space around the image (the canvas area) you will need to zoom out further (alt+spacebar and click). Even though the area of the image pulled outside of the image will not be visible, it is still there. Move the corner handle back in and that area will reappear in the picture. Even if you come back to this tool again later on, it will still contain the picture information outside of the viewable area. However, remember this is taking up memory so before you save your final image, Crop the full picture and this will remove all the unwanted bits and save you memory, making the file size smaller.
You should see something like this on your screen:
See how the building is now standing upright? That is what we are aiming for. Don't worry that the top of the roof looks jagged now, they won't as soon as you hit enter and let the editing take effect
Either hit 'Enter' or click on the Tick icon on the main manubar at top of screen.
That's it, all done :o) To see the difference you have made, click the Eye icon on the layer pallet on the top layer so the layer is made invisible. You can see the original still there underneath. Click the eye again and you can see the top layer so you can see how much difference you have made.
Method 2: The Crop Tool
An extremely quick and simple method for correcting CVs is to use the Crop tool.
Using the crop tool (see the screenshot for which icon to click on) you can usually only crop a square or rectangular part of your picture. However, if you first check the 'Perspective' box (highlighted on the screenshot) you can now drag the corner handles inwards. If you pull them in so that the side bars are parallel with the sides of the building, as in the picture above, and then hit 'Enter' or click the Tick icon on the menubar, it will crop the picture along those lines but pull the sides out until they are square. This distorts the picture pulling the building out and straight.
The term 'distort' sounds a bit drastic and destructive but you will see that it really can improve greatly the shape of your image.
If you don't like the result, just press Ctrl+Z to undo that crop and you can do it again or use the other method.
I hope this is helpful for you in your pictures. Remember, this is a very simple pair of methods so if they sound a bit complicated, just read through them carefully and I promise you'll be doing it very easily in no time
If you get any problems, feel free to PM me and I'll gladly answer any questions you might have.
Best wishes,
Rob