It's actually fairly easy since most applications designed for RAW processing all the complicated stuff for you.
But a few fundamental differences...
Your camera can capture RAW data at 14-bits per "pixel". When an image is stored as a JPEG, it's only 8-bits per pixel. So immediately you lose a lot of data when you use JPEG.
With only 8 bits, it's only possible to store 256 levels of tonality per color channel. With 14 bits it's possible to store 16,384 levels of tonality. That's quite a difference!
A JPEG image is designed to try to save space (remember... this is a standard that emerged around the time when everyone had dial-up internet ... saving space on small computer hard drives and not having excessively long download times was "a thing" back then. Today everyone has fast internet and huge hard drives. We're not so worried about download times.
To "save space", not only did JPEG use that smaller number of bits per color channel, it also did fairly agressive compression.
Suppose you take a moderately over-exposed photo of a "white" wedding dress with lots of lace. But because it's a bit over-exposed, it's extremeley difficult to see the detail. JPEG compresses based on an algorithm that suggests if your eye "probably wouldn't notice the difference" (between adjacent pixels) then it will alter the similar pixels to all just be "the same". The reason for this is that it takes less space for the computer to say "I have 10 pixels and they all have the same value: ____" than it does to say "I have pixel with __ value, another with __ value, another with ... and so on for 10 unique pixels.
Trouble happens when you realize you slightly over-exposed... didn't get the detail... and then think you're going to just back off the exposure in the post-processing software to "recover" the detail. For JPEG... that's "lossy" compression It threw the original data out to save space. You'll never get that detail back. For RAW... it saves everything. Nothing is thrown out. This means you usually CAN recover quite a bit of detail.
So after extolling the virtues of RAW, there is a trade off (or two).
The camera just saves the RAW data... it doesn't process it. Normally when you use JPEG, all kinds of things happen to the image data before th camera stores the file. It applies white balance corrections. It'll apply some sharpening. It'll do a bit of de-noising, it'll apply a color profile. In other words... it's a little photo-lab built into your camera.
With RAW, none of that happens. Everything has to be performed on the computer after the image is imported. This means quite often the "straight-out-of-the-camera" comparison of JPEG vs. RAW... the JPEG often looks better. But the RAW has more information and once processed... the RAW will look better.
Many applications which are designed to work with RAW files will automatically apply a "camera profile" to any RAW image imported from a camera. This means it knows roughly what ought to be done with the image and will do it on-the-fly as the image is imported. But it doesn't throw away the original data. The real RAW file is saved and the on-the-fly adjustments are shown on-screen (it basically builds a list of every adjustment that needs to be performed. When you open an image, it opens the original data, then runs through the list of all the adjustments and quickly applies them. The result is that what you see "on the screen" looks processed (even though the file isn't really stored that way).
The other nice thing about the fact that it maintains a seperate list of all those adjustments, is that you can re-adjust or change anything... nothing is permanent. So if you make an adjustment, and a day later you do a "what was I thinking yesterday... I need to change this" -- you CAN actually change it (for most RAW processing applications nothing is permanent. They avoid changes that would result in a permanent loss of any original data.)
I did say there was one other area where JPEG does better... and it's not the image file so much as it is the camera performance. When you shoot actcion shots, and you set your camera to click-click-click in burst mode as fast as it can... the camera saves those images to an internal memory buffer as it also tries to write all the data to the memory card. Since RAW data is smaller, you can click off many more shots before the buffer gets full.
If you're shooting action, and you use RAW, you'll hear the camera go "click, click, click, click, click......... click..........cllick" and those long delays at the end mean the buffer filled. The camera has to wait for at least one image to get saved to the memory card before it'll let you take the next image.
If you do this with JPEG, the files are much smaller and don't take nearly as much buffer space. So you'll get a lot more clicks before the buffer fills and the burst rate slows down.
Higher end cameras have much bigger buffers and also have the ability to transfer data faster... so it's not usually a problem for them.
Tim Campbell
5D III, 5D IV, 60Da
