In this era of digital cameras and smartphones, digital photography has become ubiquitous and one image format for photos has dominated all the others: the JPEG. However, for people who're more serious about their photography the RAW format is worth considering.
"JPEG has the advantage, depending on the pre-selected setting, of effectively compressing image data, similar to the MP3 in the audio sphere," says German photographer Ralf Krause. This relatively small file size means that many photos can fit on a memory card.
Another benefit of JPEG is that it is a universal format that all of the popular image viewing and photo editing programs can handle.
The nature of the RAW format is reflected in its name: "Raw, untreated and uncompressed image data is saved just as it's delivered by the image sensor," Krause says. "It's analogous to the film negative in classic photography."
RAW stores the colour and brightness data for each pixel of the image as well as the aperture, ISO speed and time of the exposure. This gives the photographer a lot of leeway afterwards to adjust parameters such as contrast, sharpness, white balance and colour when editing the photo. "A RAW file is a digital negative and must always be reworked," Krause stresses.
Plug-ins for working with RAW files are available for photo editing programmes like Adobe Photoshop and Gimp. Some camera manufacturers maintain their own proprietary RAW formats and so include software to edit the images.
It's really a format for those who want optimum image quality and maximum flexibility when it comes to editing. On a PC the ability to change a RAW image's colour temperature, dynamic range and the brightness levels is much greater than with a JPEG image.
Transitions between black and white can also be graded much more finely and RAW is a good format to use when shooting in difficult lighting conditions.
If a photo is to be posted on the internet or emailed to friends immediately after it's taken, it makes more sense to use the JPEG format. That's because every RAW file requires manual work. "Automatic transformations don't make sense, so photographing in JPEG format is by far the better alternative, because the camera makes all the settings perfectly," says Krause.
To get the best of both worlds, many cameras offer the option of saving images simultaneously in RAW and JPEG format.
Once you've edited your RAW files, they're best saved in uncompressed TIFF or BMP formats. Krause also recommends archiving the RAW files on a really big drive somewhere so that you can always return to the original later, bear in mind how enormous those RAW files are compared to JPEGs.
"For example, a picture taken with the 13.1 megapixel camera of the HTC One A9 phone in JPEG format is 3.5 megabytes in size. The same photo as a DNG photo is 25 megabytes in size," says Margrit Lingner from Germany's PC Magazin. DNG is that device's RAW image format.
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