What’s the deal with digital processing?
If you shoot JPEG s or movie clips, you need to pay more attention to the treatments your camera applies, compared with shooting raw…
Last issue we looked at raw files, and why choosing to shoot raw inevitably means spending additional time in front of a computer in order to process your images. You can, of course, let your preferred raw software automatically take care of the image processing business for you, but it’s hard to resist tweaking sliders and generally getting involved.
But what if you don’t want to have to do that? What if you want to shoot JPEGs and get the image ‘right’ in-camera? In this case you need to make sure that as well as getting your pictures in focus and well-exposed, the way in which your camera will process your images is set up correctly for each shot.
Digital image processing is essentially a series of software adjustments that are applied once the sensor has been exposed and your photo is converted into a digital form. Your image actually starts out as an electrical signal generated by the camera’s analogue image sensor; this can be tweaked by electronic circuitry to increase the ISO sensitivity, for example (which is why an image’s ISO cannot be changed in digital software at a later stage).
Once the image has been converted into digital data, which uses the same binary language as computers, your camera’s image processor crunches the huge amount of information that’s
created. Adjustments are made to the white balance, gamma curve and sharpness, colour and contrast, before the image is temporarily stored in the camera’s buffer memory and, from there, written to the memory card.
If you shoot a raw file, this digital information is stored in a file alongside the image data, allowing you to select different processing treatments when you open the file in raw software; if you shoot a JPEG, the digital processing effects are applied to the image before it is written to the memory card – and there’s no going back later. When it comes to the processing side of things, you can leave the camera to do everything or you can make adjustments manually. White balance, noise reduction and lens corrections each get their own dedicated section in the camera’s menu or control screen, but rather than picture processing options such as sharpening, saturation and contrast being listed individually, they are typically bundled together as one-click picture presets.
Camera manufacturers have adopted different brand names for these presets. In the Canon EOS universe, they’re
Sharpening, saturation and contrast are usually bundled together in one-click picture presets or colour profiles
Despite some of the presets sharing the same name as a camera’s shooting modes, they have no control over other camera settings
called Picture Styles; Nikon cameras have Picture Controls; and on Sony cameras, it’s Creative Styles. There is some variation in the numbers and results of these presets between different manufacturers, too. They all tend to offer the same core set of options, though, ranging from a standard colour setting to a black-and-white one, and profiles tailored to both portrait and landscape photography.
Despite some of the picture processing presets sharing the same name as a camera’s automatic shooting modes, they only affect the look of your pictures or movies and have no control over other camera settings. For instance, if you select the Portrait shooting mode, your camera essentially becomes a point-and-shoot, with everything from the autofocus to the exposure being decided for you. But all that the Portrait picture preset does is adjust the colour tone and reduce the sharpness to produce softer, more flattering skin tones.
In addition to using the default presets, you can choose to customise the settings or develop your own mix of sharpening, colour and contrast, and save these as a new preset. Some cameras allow you to adjust the parameters separately to the main profiles. For instance, Fujifilm cameras offer ready-made profiles based on their classic films, such as Velvia and Provia. But as well as selecting the Film Simulation, you can tweak the colour and sharpness elsewhere.