Photo Tip of the Week: JPEG or Raw?
Because Raw files contain more information than JPEGs, it's possible to recover details in shadow and highlight areas that would otherwise be lost in a JPEG file. In this image, which was photographed in Raw, it was an easy matter to lighten the shadows in the pylon. Photos by James Ostinga. (See larger version below.)
Most cameras these days offer a choice between Raw and JPEG. Deciding which one you should use comes down to a choice between image quality, file size, speed and convenience. James Ostinga and Andrew Fildes outline the pros and cons of the two popular image formats.
JPEG files are considerably smaller than Raw files. The difference varies, but to give you an idea, a Large/Fine JPEG from the new 18-megapixel Canon EOS 650D is around 6.6MB, compared to 25.1MB for a Raw file. That means you’ll fit around 600 JPEGs on a 4GB card, compared to 150 Raw images.
Because JPEGs are smaller, image playback, continuous shooting and other camera functions are generally faster when you shoot JPEG.
A big advantage of shooting JPEG is convenience. JPEG images are ready to share, print and store, straight out of the camera. The same can’t be said for Raw files, which must be post-processed in a computer with special Raw editing software, then saved to another format, such as JPEG, TIFF or PSD.
Raw is the clear winner when it comes to image quality. The big advantage of shooting Raw is that the files simply hold more information and image detail than JPEG files. The compression algorithm that makes JPEG files smaller works by discarding unnecessary detail, such as small differences in similar tones. The trouble is, that detail can be very useful. The difference may seem small but it becomes more noticeable as you zoom in on your images or make large prints.
SHADOWS AND HIGHLIGHTS
Because Raw files contain more information than JPEGs, they make it possible to recover details that would otherwise be lost in the conversion to JPEG. That’s particularly true in the shadow and highlight areas. If your image is perfectly exposed, the need for Raw is reduced. However, if your image is slightly under or over exposed, the benefits of shooting Raw are considerable.
Some variables are much easier to adjust in post-production if you shoot Raw. White balance is a good example. With Raw, setting the white balance is simply a matter of choosing from a list of common presets – such as daylight, tungsten or fluorescent – or moving the colour temperature slider till you’re happy with the results. Shoot JPEG and the correction is much more complicated – that's because the camera has already applied it’s own white balance settings to the image.