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Take control of your photos with RAW for free

Posted on 28 Feb 2011 at 16:35

Darien Graham-Smith explains how to process RAW image files to achieve professional results

If you’re lucky enough to own a digital SLR, chances are you’re using it in JPEG mode, rather than shooting in the camera’s native RAW format.

And for everyday snaps that’s a more convenient way to go: JPEG images can be instantly viewed, edited and shared, while RAW files have to be processed on your PC using specialist software. You can fit more JPEGs on your memory card, too, since they’re typically around a quarter of the size of RAW files.

However, professional photographers invariably prefer RAW mode. If you want to improve your own results, you can do the same – without having to invest in professional-grade software. To see what you can achieve, and how, let’s first examine what shooting in RAW mode means.

RAW files vs JPEG

When you take a photo, your camera records the light and colour levels across the scene – the “raw” data of the photograph. This happens the same regardless of whether you’re shooting in RAW or JPEG mode.

If you want to capture every wisp of a spectacular cloud formation, or explore the shadows and shades of a gloomy cave, your best bet is to take the shot in RAW mode

But in JPEG mode this data is then converted into a compressed image, whereas in RAW mode it’s stored on your memory card as-is, for you to convert yourself at a later date. (You can also choose to shoot in JPEG + RAW mode, in which case both representations will be kept.)

There are two reasons why you might want to work from the raw data, rather than using JPEG. For one, it’s well known that JPEG compression is “lossy”, meaning it doesn’t retain all the detail of the source image.

It’s fine for everyday use, especially with pictures that are destined to be shrunk down and shared online; but if you ever want to get a photo printed in large format (one of the joys of amateur photography), or if you need to zoom in on a particular area of a photo, you’ll find JPEGs up close have a murky, noisy quality. The original raw data will give visibly cleaner results.

RAW mode also gives you control over the exposure and colouration of the final image. When you shoot in JPEG mode, your camera tries to apply exposure settings that produce a picture that’s neither too bright or too dark, and which doesn’t suffer from an obvious colour cast.

Normally this gives satisfactory results, but sometimes it can be off. If, for example, you try to brighten a JPEG to bring out the detail in darker areas, the result will generally be lacking in clarity.

That’s because the conversion loses not only detail but also tonal depth: a JPEG can record just 0.02% of the shades that a typical RAW file can represent.

So if you want to capture every wisp of a spectacular cloud formation, or explore the shadows and shades of a gloomy cave, your best bet is to take the shot in RAW mode – after choosing the appropriate shutter and aperture settings, of course, because not even RAW mode can save you if the camera is unable to pick up the detail in the first place.

You can then adjust the exposure settings at your leisure, on the big screen of your PC, to get an image that reflects the full clarity and tonal range of your camera.

Processing RAW files with RAW Therapee

Serious photographers tend to process their RAW files using Adobe Lightroom, while others may use Photoshop or Photoshop Elements. But for basic digital developing there’s no need to pay a penny: you can use the open-source RAW Therapee program, which you can download free here. Let’s walk through a typical process in RAW Therapee.

Open the application and the fully featured main screen will appear. At the bottom left you’ll see a file browser: click on a folder and thumbnails of all the images appear in the pane to the right.

You can open all kinds of images, not just RAW files, but not all features are available for non-RAW files. We’ll use a winter night-time scene, which we’ve shot in JPEG and RAW mode – so we can process the RAW file ourselves, and compare the results to the camera-generated JPEG.

Double-clicking on the RAW file makes it open in the main RAW Therapee pane. You can zoom in and out using the tools beneath the image, and ticking the Detail box will open a close-up view so you can see the effect of your changes at the pixel level.

The “Preview scale” dropdown lets you work with a smaller preview, giving faster feedback for your adjustments but less ability to zoom in. The 1:4 option is a good compromise.

The first thing we want to do with our image is reduce the sodium yellow glare from the streetlights. Correcting colours is simply a matter of selecting the eye-dropper tool above the image, then clicking on an area of the image that’s supposed to be a neutral tone: the overall hue of the picture (its “temperature”) should shift to take on a more natural appearance.