Most digital cameras with the exception of inexpensive point-and-shoots will shoot either raw or JPG images. Some of the top-end DSLRs can shoot in TIFF format as well.
Here’s how I explain it in the classroom.
A JPG image is like a cake you’ve baked and iced. When you shoot a JPG the photo in your camera has all the parameters of brightness, contrast, colour saturation, white balance (which we’ll explain later) and many other similar attributes already baked into the image. In software like Photoshop or lesser editing programs like IPhoto or Elements you can modify things like brightness and color a little bit and crop your image. But JPGs are meant to be viewed online or printed in a printer just as they are. And in most cameras, the JPGs you shoot and view are essentially perfect.
A raw format image is like a cake recipe. When you shoot the photo your camera records all the ingredients that goes into a photo such as brightness, contrast, colour saturation, white balance and a whole lot more and leaves it up to you to make the JPG photo in software.
So when you shoot in raw format the image you see on your LCD screen or through your viewfinder is a JPG that the camera creates just for the purpose of viewing. This low resolution JPG isn’t stored or remembered by the camera. All you have is the raw image. Raw images when initially viewed when using a photo editing program like Photoshop or IPhoto will appear somewhat flat and dreary as nothing has been done to ingredients yet to bake and ice the cake or in our case to make the image into a JPG (or a DNG or TIFF which is another form of raw image used by other photo editing programs).
They both are. Shooting JPGs allows you to project, display or print your images right out of the camera. The images might benefit from cropping in software or be brightened or darkened a little but that’s about it.
Raw images, which are substantially bigger than JPGs (a JPG image has much of its digital information discarded once it is recorded on the memory card), will accept greater degrees of manipulation in software. There is much that can be done to make a raw image look better but this takes time, software and some training (not as much as you might think for most things). The large size of the basic raw image means you get less images per memory card and some cameras may take a split second or more to ingest the image and move it into memory.
I usually shoot JPGs when I am shooting exclusively for web display and if there is a need for a print it’s a print that is no larger than an 8″X10″ or so. I had a job shooting a day-long baseball tournament. The images were to be projected that evening at the tournament dinner. I shot hundreds of medium-size, medium-quality JPGs which loaded instantly (as they were fairly small in size) and without any software editing to a computer which projected the images to a screen setup at the dinner. If I had to print from these JPGS I could easily get 4″X6″ out of any of them and maybe go as big as 8″X10″.
I shoot raw when I know I’m shooting images which I may print as large as 16″X20″ or sell to a client for use in magazine advertising. All my wedding photography is shot in raw format and edit extensively in Lightroom 4 or Photoshop CS6.
Now when it comes to my vacations I shoot both raw and JPG images depending on the vacation and on the subjects I’m shooting. Photo-related vacations or vacations where I think I might want to print large photos or make a photo book are shot in raw. Fun vacations where the majority of shots are going to an online gallery or emailed to friends are shot as JPGs.