Photography: RAW versus JPEG formatsThis entry discusses Digital Photography terms and their meanings. Specificially it covers the differences between the JPEG format for digital photography and the RAW format. Benefits of working with each are also discussed.
As many of you know I am an avid photographer (I didn't say good necessarily, just avid ;-). Well recently as you may know I got my first 'pro level' Digital Camera. As I began to get into the new medium (digital vs. film), I realized these cameras can be as simple or as complex as you want. One thing that initially baffled me was why the camera gave me a choice between taking pictures in JPEG mode and RAW mode. After hours of research (and hundreds of test shots later) I feel I have a really good grasp on the subject and wanted to share some knowledge. (I will also be writing up a followup to this article once I get my hands on Apple's new iPhoto 05' to discuss its RAW support.)
A little background on RAW.
Many of today's high end cameras give you the option of how you can deal with your digital photos: you can have them saved as a JPEG (which is the standard format that can be emailed, or viewed on a computer, etc) or in the RAW format. The RAW format is exactly like it sounds: it is a 'digital negative' - it is RAW and unprocessed by the camera. When you shoot a picture using your camera's built in JPEG functionality, the camera makes lots of decisions for you in regards to white balance, sharpness and several other factors, and once it does this it discards the information that it does not need. In many situations this is not a bad thing, as it saves time and can often give you good results (depending on the camera) and makes the file sizes much smaller.
While it often will give you good results there are always pictures where the camera "gets it wrong." And that is exactly where the RAW format comes in - It gives you ALL the data captured by your camera and lets YOU decide all those settings. If you take a great picture - GREAT, no further correction will be required, however if you did miss something or your camera was a bit underexposed for example you have full control to fix it in a non-destructive manner. For someone who is serious about their photographs, or really for anyone who doesn't like the idea of their camera deciding what looks good for them: RAW is just the ticket.
Another great feature with shooting in RAW is this: Once you have your RAW file you cannot accidently overwrite this file with changes - it is like a digital negative - you can make copies from it, but you cannot change it directly. This is both a pro and a con. For example: If you want to use your picture in a word processing document, or in an email (or practically anything but viewing and printing) you will have to save a copy of the file in a more standard file type (like JPEG). This, as you would expect, takes more than twice the space (as RAW is a bit larger than JPEG). While the storage space is more, you ALWAYS have an un- compromised "digital negative" to refer to incase you want to go back.
Why RAW is difficult.
Shooting with RAW is a double-edjeged sword: it gives you PLENTY of benefits, but at the same time means you will will have to take your pictures into a program that can manage the RAW pictures. At the current time there are few programs that even understand the RAW format and most of them are not free. Examples include professional software like Adobe's Photoshop CS and the camera vendors own proprietary (and often clunky) software. So if you have a RAW picture you want to send to a friend (or use it for some other purpose) you will first have to open your image in an image processing application (like the ones mentioned) and then save it into a more portable format.
JPEG's Achilles heel.
You might be asking yourself: If it is so difficult to work with those RAW images, and it takes all these extra steps to work with them, why wouldn't I just keep shooting JPEG? This is a valid question and one that has several answers: I will cover two of them:
- JPEG is a lossy format. What does that mean? When you save an image (like a JPEG, TIFF, GIF, PNG, etc) it is compressed to make the file size as small as possible. Now some compression methods are lossless meaning they non-destructively compress the file (and conversly, when you open them there is NO loss of data, and some are lossy meaning when compressed bits of the file are lost. This is very similar to the way MP3 or AAC files work with your digital music: the program removes pieces of the file it feels are not needed in an effort to reduce the file size. With JPEG's you have the option of choosing how much you want to be thrown out when your picture is saved, but it will ALWAYS lose some data.
In general this is not a huge issue, but when you are wanting the very best in image quality, having some of your image thrown out each time you save your file is not a real option. As I mentioned, you can choose how little of the file is removed when compressing: The picture to the above to the right illustrates (on a drastic manner) what a file looks like that has been drastically compressed. Though you may not be able to see all that is lost by saving in JPEG, it is significant.
- Image Quality is not as great with JPEG. When the pictures are compressed using the JPEG format some of the fine detail is lost forever. When taking pictures of fine detail using the JPEG and RAW formats, you can really tell the difference.
Working in the RAW format has several advantages; but as with all things in life, you trade off in file size and ease of use. If you have a camera that supports the RAW format, I would suggest giving it a try. For now you can use your camera's defalt software (or Photoshop if you have it), and later you can try out Apple's new iPhoto 05'.