The Gentle Art of Compositing

Clive R. Haynes FRPS


Almost since the dawn of photography, photographers have sought to combine images together. The combinations can be for aesthetic purposes, for reasons of practicality or to produce a 'vision' that exists in only the imagination of the artist.

Digital imaging affords yet more scope for the photographer/artist.

Generally speaking, the more subtle the combination the more pleasing the result. However, some crude cut & paste amalgamations can have a primitive delight all of their own. It all depends upon what you wish to achieve and communicate.

There are many considerations to be made before one begins to combine images and here are some thoughts.

The relative scale of the individual images

The textural integrity of each image

The direction of lighting for each image

The colour tone of each image

The 'sincerity' of the overall effect

Most of the problems are best resolved at the 'taking stage' by the art of 'previsualisation' - that is to say, wherever possible, be aware of the final picture you have in mind as you photograph and 'assemble' the various components for the image.

Taking the above topics one at a time, below are thoughts and practical advice.


Scale of the individual images

If you are unable to photograph the images for your composite picture individually at the correct scale for the final result then you will have to alter their relative size in some way. Commonly, people simply re-size the components via the Edit > Transform > Scale route. A small amount of re-sizing is generally acceptable, however this method is not always the best answer, as pixels are either invented or discarded in the process. The final image can suffer a 'definition differential' i.e. some parts being either sharper or fuzzier than others - see 'Textural Integrity' below.

To go some way to overcome this problem, it's preferable wherever possible, to import the individual images for the intended composite picture as close to the scale required as possible. This can be done via the scanner. What follows is based upon a neg/pos scanner (Nikon Coolscan with Silverfast software) but the general principles should apply to any scanner where the scanner program displays the parameters in question.

If your images are held on a c.d. then you cannot do this and you'll simply have to follow the 'transform' route.

The first step is to define the area on the base image that you wish to bring the new picture into. Do this by the following steps.

Check your image size via Image > Image Size and note the resolution/ppi

Use the rectangular marquee tool to establish the area (as near as possible).

Go to the 'Info' palette

Look at the W & H (Width & Height) shown - these are the dimensions selected by the rectangular marquee.

Keep the 'Info' displayed

Open a New file (via File > New).

Make certain that the resolution/ppi for this new file is identical to the base image (you noted this earlier).

In the Width and Height boxes enter the W & H figures from the Info palette.

Note the File Size (in Mb) that is now shown - write it down.

Close the New File box - it's done its job as a 'calculator' for you.

Go to your scanner.

Pre-scan the image you need.

Adjust the marquee to embrace the area you wish to import (helpful if it can be relatively the same shape and proportion as the area you established on the base image earlier).

Adjust the dpi/ppi (by adjusting the slider control or by typing in different amounts and so far as Silverfast goes, keep 'scale' at 100%) until the File Size (in Mb) is the same as or perhaps a small percentage more than you require. Whatever scanning device you are using it's the file size in Mb that's the important factor.

Next - Scan.

With two windows running in Photoshop, one showing the newly scanned image the other showing the original/base image, if necessary, go to Image > Rotate Canvass. Next, go to the new image, select the Move tool and drag the new image onto the original/base image (it moves so far then changes to a small square with a + sign - keep going!).

As if by magic the new image will now be at the scale you need and on its own layer. Should any small change to the scale be required, the 'transform' menu can make this.


Textural Integrity

We've already touched upon this issue.

When combining images photographically beneath the enlarger it was always considered 'bad practice' to combine a fine grain negative with a course grain negative in the same scene - well, if it showed that is.

Imagine a finely delineated landscape to which a dramatic sky has been added. The sky having originated from a fast, course-grained film and the landscape from a slow fine grain film. The evident granular quality of the sky would not sit easily with the image. There would be a lack of 'textural integrity' so to speak and the image would be uncomfortable.

The same situation applies digitally too, for not only can we repeat the error above but compound it with other misjudgements.

The question of scale and definition has already been addressed. Make certain that the composited image appears to be part of the original scene texture-wise and sharpness-wise. Avoid images that look too sharp for their surroundings, if necessary use one of the softening/blurring tools to subtly reduce sharpness.

Should you be faced with the problem of too obviously a grain-free area in an image where the grain is prominent, add some 'Noise' via, Filter > Noise > Add Noise. This problem can frequently occur, especially in areas of continuous tone. The judicious addition of 'noise' will help.


Direction of Lighting

As fundamental as it may appear, many multi-image pictures are ruined by poor attention to lighting and shadow details.

Indoors or under artificial lighting you may get away with it but outdoors, where we expect there to be just the one light source i.e. the Sun, two or more shadow angles will bring the image into question.

The problem of lighting direction can often be easily overcome by flipping the image horizontally via Edit > Transform > Flip Horizontal. Sometimes the original shadow will need to be stripped away (possibly by using a Layer Mask) and a fresh shadow added either via Layer > Effects > Drop Shadow with further adjustments via the 'Transform' options, or by carefully painting one in.

Don't forget the direction of the key light either, as the highlight-side of the area you're working on will also need attention to make the image convincing. If it's really difficult to change things without it looking obvious - and Photoshop can't help with everything - don't do it, choose something else or shoot the required item again.


Colour Tone

This is a similar problem area to lighting. If you're bringing in different images, shot at different times, on different films, indoor/outdoor etc, then it's inevitable that you'll have to make some adjustments to these individual components of the picture.

Make these adjustments with an Adjustment Layer for each image concerned. See the notes about Adjustment Layers and Clipping Groups in another paper.

Use one of the following to make these changes and it can be tricky, all via Image > Adjust >


Color Balance

Selective Color

Channel mixer



This is probably the most difficult item to discuss, as Photoshop certainly has no such function in its program.

Sincerity is about what YOU are making with YOUR image and what YOU intend. Whilst it's true to say that in art there are really no 'rules', only 'conventions', think seriously about what you are doing - stand back for a moment and consider. Is the effect you're striving to achieve rooted in some form of reality? Will it confuse or intrigue the viewer? Is the overall effect merely an effect for its own sake? - in the "I can do it, so I will - arenít I a clever person!" school of art. Yes, we've all done it, we've all been there and we've all seen images of strange and distorted faces and wings fitted to things and the like.

Think to yourself -

"When I've completed this picture, will it add up?"

"Will it tell us more about the object/scene/emotion/person portrayed or extend our knowledge in some way?"

"Will it be amusing and intriguing or simply weird and confusing?"

"Will it be true to its own internal logic?"

Sincerity is a vast issue and there are no black and white answers, only shades of grey.

The important thing is not to get carried away with an idea or series of effects for their own sake. Try to remain faithful to your internal vision and not to be side-tracked by the weird and wonderful things you can superimpose on a scene.

The most telling pieces of work are those with a simple and direct message, delivered in an uncluttered way.

The very problem with making the statements above is that many examples can be found that appear to contradict them. At least I hope I've made you stop and consider.

Related Topics
Importing An Image to Scale
Know-How Contents
e-mail CRHfoto