Tuesday, 13 September 2016

Putting a Key Line around a projected image

Our judge at the last PDI competition, Roger Mendham, made several interesting comments about the use of 'key lines' around projected images, and Mark tells me a few people were asking him how to do it. A few general points before I tell you the simplest way..

I remember one of the judges a year or two ago saying that you should always put a key line around PDIs.

This is nonsense. There are no rules in photography.

A key line holds in the edge of an image and helps 'contain' it. In effect, you are saying 'This is precisely the composition I have extracted from the real world and I want you to concentrate on it.'

However, you may not want to 'contain' the image like this. A good example was Mark's picture of the Aurora Borealis (Tempest) where the judge said the starry sky would have been ruined by a white key line. The night sky goes on and up to infinity so why box it in?


'Tempest' (by Mark). Click on the picture to see full size.

Remember that your image is projected against a black background and if you have dark areas near its edges, these may just dissolve into it. A white key line is not so important if a light area like the sky goes right to the edge. Note I have added an extra black border to the pictures on this Blog to give you a better idea of how they will look projected.

Key lines can be added very easily in Photoshop or Elements using the Stroke command. With this command you can add a line to any selection you make. The width (in pixels) can be set, and any colour can be used. Don't use black as it won't be visible against the background when projected.

Always add the key line AFTER you have resized the picture for projection. I have noticed on occasions that our projector seems to miss displaying the outer pixels in a full size image, so I would advise you to resize down to say 1022 pixels wide and 766 pixels high as a maximum, rather than 1024 x 768, to make sure the key line is displayed.

First decide what colour you want the key line and make sure the Foreground Colour is set to this. If you want to use a colour picked from the image itself, use the Eyedropper tool and click on the image there.


'Brimstone Butterfly in flight' by Mandy. (Click on the picture to see full size)

To place the line at the very edge, select the whole of the picture - Select/All in the drop-down menu, or use the keyboard shortcut Ctrl/A.

Next, in the Edit drop-down menu click Stroke. A Window opens giving you the  option to choose the width of the line in pixels. You can also select where the line is added, either Inside, Outside or Centred on the line. Choose Inside, then click OK.

Hit Ctrl/D to remove the marching ants and you will see the key line. View the image at 100% to see what it will look like projected.

It is a question of taste (and message) how thick you make the line. I tend to keep it to 1 or 2 pixels wide. Too thick and it can be a bit distracting and make the picture look like an EnPrint from Boots - but of course, that may be what you are aiming for.

Ask yourself whether the line improves what the picture is trying to say. Otherwise, it just distracts from your picture and is just an affectation.

Of course, there's no reason why you can't have a bit of fun with it.


'Escape velocity' (by Yours truly..)

Hopefully, at one of our demo evenings I will have a chance to demonstrate all this.

I keep six honest serving-men
(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who


'Just So Stories'   Rudyard Kipling

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