Film users who’ve migrated to digital might find that their new cameras don’t quite mirror the depth of colour provided by film. This is due in part to the pretty conservative way that digital cameras process their shots, generating images without excessive saturation or contrast so that the majority of scenes are rendered well and have the scope for further manipulation later. It’s perfectly possible, though, to increase colour saturation, either at the time of taking the photo or later on using software. Which method, though, gives the best results? It’s important to understand the pros and cons before you start shooting.
In-camera or in-computer?
Why bother increasing the saturation setting on the camera when you can do it in your image-editor later? Because the camera will be able to apply the adjustment as it processes the raw sensor data. Every time image data is processed, some information is lost and the remainder is slightly degraded. It’s better for the data to be processed only once (in the camera) than twice (later on again in your image-editor). When you apply saturation increases to PEG images. you’ll often start to see increased noise or blotchiness which, carried to extremes, will ruin the image. If you want higher saturation, then, its best to apply it in-camera, even though this might be more fiddly.
Problems to be aware of
So what do saturation problems look like? They come on subtly, and they’re easy to overlook if you don’t know what you’re looking for. The JPEG file format uses mathematical compression techniques whereby the image is split into small squares that are analysed individually. If you increase the saturation, this pattern of squares can become visible. You may also see an Increase in noise, particularly in areas of solid colour. This can appear as random speckling or irregular patches of stronger colour. Because of the way digital cameras calculate colour values and sharpen fine detail, object edges often have a fine ‘halo’ around them. This is normally not too obtrusive, but big saturation increases can emphasize any trace of colour they possess, generating rather obvious coloured outlines. Other problems include ‘clipping’, where image detail is lost and objects degenerate into blobs of solid, featureless colour, and colour distortions, where some colours undergo disproportionate colour increases or colour shifts.
Many people imagine that filters are no longer necessary with digital cameras. After all, can’t you do everything in Photoshop? Not quite. Some things are still easier to achieve with filters than with Photoshop, while other effects still can’t be duplicated any other way. Warm-up filters are still useful, not because you can’t warm images up in Photoshop, but because they often produce more natural•looking results and because it’s at least as quick as trying to juggle the image’s RGB values later. Don’t fall into the trap of taking any old shot and assuming you can make it perfect in Photoshop. Shooting things right is always preferable to trying to make them right later.
Polarising filters are a special case. Firstly, they can dramatically darken blue skies. Secondly, they cut down glare from reflective surfaces such as glass, plastic, and water, increasing saturation as a result. This is an effect you simply can’t mimic later in Photoshop. Polarising filters can be expensive, and if your camera’s lens has a rotating front element they can be fiddly to use, too, because you’ll have to re-adjust the orientation after the camera’s focused. They also cut down the amount of tight by 2-3 EV values, so you may need to increase the cameras ISO in poor lighting to avoid camera shake. There’s no need to adjust the camera exposure since it’ll compensate automatic*. The only exception is where you want to preserve the depth of a blue sky. Here, rotate the filter so there’s no darkening effect, lock the exposure, then turn the filter to darken the sky and shoot.
If you use filters on your camera, this can have an effect on the white balance, depending on the filter type. Polarisers are neutral — they don’t change the colour balance, only the depth of colour. Warm-up or other colour-adjusting filters will, of course, change the colour of the light. The thing to make sure of here is that you don’t leave the camera set to auto white balance, because it will simply attempt to compensate for the changed light colour. Always choose an appropriate white balance preset before using a coloured filter. One interesting alternative to a ‘straight’ coloured filter is to use a coloured graduate. This will add a colour to the sky without changing the foreground colours. A blue grad can add a sunny feel to an overcast day, while a yellow/orange grad can add drama to a stormy sky. With these, it’s wise to take your meter reading before you fit the filter.