JPEG Versus RAW files
By Geoff Harris •
A JPEG is a compressed image file, and it is smaller in size than a TIFF, PSD or a RAW file. This means that you can fit more photographs on your memory card or your computer hard disk if they are JPEGs – which sounds like a good thing.
But –inevitably! - there is a downside. The compression of the file will come at the expense of a loss of quality.
Nevertheless, there are times when a JPEG will be just what you need. So let’s look at the pros and cons.
There are two stages at which you might choose to use the JPEG file format. The first is when you take the photo.
A digital camera can save images as various different file types, most commonly RAW files and JPEGs and sometimes TIFF files. There is also usually an option to choose the size of the JPEG, from fine through normal to basic, with basic being the smallest file size of all.
The second stage where you have an option to choose JPEG is when you save an image on your computer. If your original image was a RAW file, you can choose later on to save it as a TIFF or a PSD, or as a JPEG file.
JPEGs take up less memory space because they take the image data and compress it.
But as the data is compressed, a large chunk of the information is discarded.
If we look at the difference between a JPEG image taken in camera and a RAW File of the same subject, the raw file is 27.3MB in size while the equivalent JPEG is only 1.97 MB for an identical file size of 3840 x 5760 px.
Somewhere we have lost over 94% of the file information. When you set you camera to JPEG rather than RAW the camera discards 95% of the image information which you can never get back. This is why JPEGs are known as lossy files.
Also, each time that you open a JPEG to edit it and then re-save it, up to 50% of the remaining information will be lost.
Open and save the file 4 or 5 times and the quality of the image may deteriorate to such an extent as to render the file unusable.
The other thing to realise is that a RAW file is 12-14 bit depending on camera type, while the JPEG is only 8 bit. (A bit is a unit of colour information).
If the camera records 12 bits of data, then each pixel can handle 4,096 brightness levels, and if 14 bit, then it can record 16,384 different brightness levels. This compares to only 256 brightness levels for an 8 Bit JPEG.
In the end, your decision about which file format to use will depend on what you want to use the photo for. If you don't intend to alter it in any way and plan to post it directly to the internet – on a website or a Facebook page, for instance – then a JPEG will be absolutely fine. JPEGs are also perfect for PowerPoint presentations or digital slide shows. A high quality JPEG will usually be fine for making a good print from too.
But if you think that you may ever want to make a large print from the image, or even have it published somewhere, then it’s better to make your original photo a TIFF or a RAW file. You can still make a JPEG from it to use on the internet, but keep your larger file intact as well in case of need. Then you have the best of both worlds!
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