SHOULD I SHOOT IN RAW OR JPEG? PART 1
Which file style should you use – RAW or JPEG? In part one of this series, we explain the main differences between the formats
One of the questions most asked by enthusiasts or people with a new camera is which file format to use. Conventional wisdom dictates that, for ultimate control and image quality, the camera Raw – or as we call it, ORF on Olympus cameras – is the best, however, some photographers still cling to the easier-to-use JPEG. Both formats have their advantages, depending on your type of photography and your workflow.
What is JPEG?
The name JPEG is short for Joint Photographic Export Group and was set as a standard in the early days of digital imaging and graphic computing, as a standard file format that could be read by any digital image software or web browser. Even before digital cameras as we know them, photographers and designers were using JPEG as a means of sharing images across computer platforms – and of course the early Internet, as the images could be opened by anyone with the right browser or software.
JPEGs are processed in-camera: setting white balance, exposure, sharpening, colour and contrast, amongst others. Unless you have overridden the default settings in the menu, these presets are determined by the processor and firmware programmed into the camera.
JPEGs are also compressed by the camera, rendering fast transfer of the data to the memory card, and allowing a high number of images to be recorded. The compression algorithm used by JPEGs is lossy, – some information is destroyed in the compression. For example, the processor recognizes flat expanses of colour, and chooses an average of the pixels that make up the colour. Some of those pixels are then deleted and replaced later on the computer. Typically, at minimum compression, the compression is around a third of the original file size – so an 18MB file is reduced to 6MB.
What is Raw/ORF?
Raw files are sometimes referred to as the digital negative, and are composed of the original data from the sensor, bypassing much of the camera’s processor functions, although some of the data is saved in an embedded file within the final Raw file as metadata. A small JPEG preview image is often also embedded to allow the camera’s LCD or other device to show the image.
Because there is no in-camera processing, you need to process the files on a computer using dedicated software supplied with the camera – Olympus Viewer – or via a third party developer, such as Adobe Lightroom.
Raw files are also slightly compressed by the camera before writing to the media card, though (crucially) it is lossless compression, so no data is lost. Typically, this compression results in a closed file size around half that of an open file – eg an 18MB image compresses to 9MB.
Raw files are not usually set as a standard, so the software you use needs to be compatible with the camera model – Olympus Raw files are appended as ORF (Olympus Raw Format) and can be easily read by your Olympus Viewer software, or a compatible third party Raw reader. Software supplied by another camera manufacturer will not be able to read them.
It’s also worth mentioning that each ORF file is specific to the camera model as well. An ORF file from a Olympus OM-D E-M1 is different to that of an older Olympus camera – so if you’re upgrading your camera, you may also have to upgrade your software to make sure the new files can be read.
This is also one of the reasons why you can’t share your ORF files directly onto the Internet – web browsers simply can’t handle the multitude of different file types from hundreds of camera models and brands.
One of the major advantages of Raw over JPEG is the ability to shoot and edit in 16 bit mode. Most cameras, including Olympus CCS cameras shoot at 12 bit, with the conversion made in the software to 16 bit. This effectively doubles the size of the file (in megabyte terms) and increases the levels of tonality and the amount of fine detail in the image.
JPEGs are only 8 bit, so there’s much less information to work with. This is one of the major causes of image degradation in JPEGs when using pixel based image editing tools. Whenever you make changes, some information is lost which may lead to fine detail and tonal loss.