Your Eyes, Camera Sensors and RAW shooting- explained simply
Want to understand the difference between JPEG and RAW? Read on for a simple explanation…
How many shades of grey can you see?
20… 40… 50?
Although there are a lot of variables, the average human eye can differentiate between approximately 450 to 500 shades of grey!
What about colour?
If you guessed around 10-12 million, you would be right!!
What about camera sensors?
Well- first some background. Camera sensors are amazing pieces of technology. Take the Nikon d800e– it has 36.3 megapixels- that’s 36,300,000 pixels. Now each pixel is divided into 4 smaller sections to record individual colours (Red, Blue and 2 x Green)- making approximately 145 million little “buckets” for collecting colour information about you photo.
A “bit” is a unit of information. If you have a 1 bit photo, the only colours you could use would be complete black, and complete white. Only two choices, 0 or 1.
Make it 2 bits, and you have 2 x 2, or 4 choices. Getting better.
3 bits- 2 x 2 x 2, or 8 choices. You get the picture.
Cameras record somewhere between 12 and 14 bits (some new cameras even higher), so that gives you somewhere between 68.7 billion (12 bit), and 4.4 trillion (14 bit) colours!!!
4.4 trillion– that is a lot of colours.
And you and I can only distinguish between about 10 million of them.
So, what’s the point of all those colours?
Most of you will have heard the name JPEG, you may have noticed it coming up beside the names of your photos. It stands for “Joint Photographic Experts Group”.
So, what do these “Photographic Experts” have to do with your photos?
Actually quite a lot…
Using the JPEG format has several advantages:
- it’s easy
- the photos usually look good
- the files are small- so you can fit lots of photos on that memory card
- you can download them quickly
- you can look at the photos as soon as you get home, on the computer, on the TV…
- and all computers can read them without special software
The Joint Photographic Experts have made some decisions about your photo- they may add a little contrast, saturation, sharpness etc- and all this is done in the time between taking the shot, and the image appearing on your camera screen! Now these Experts know quite a lot about photography, in most situations they will get it right. However, if they get it wrong, or just not to your liking, then you may have a problem.
A JPEG is stored at 8 bits- giving you 256 tones of Red, Green and Blue. This gives a total of 16.7 million colours (256 x 256 x 256).
JPEG photos take all the information collected by your camera sensor (potentially trillions of bits of data), decide what the final photo should look like, then throw all the extra data away. Throwing away all that data saves a lot of time and space, and is generally a good idea… unless either you or the camera made a small mistake (wrong exposure, wrong white balance, etc). If a mistake was made when the shot was taken, you do not have that data anymore. It is gone. For good.
Now, before you race off and change your camera settings to RAW- be aware that you need special computer programs to read a RAW photo. Most computers with standard software will simply say- “unable to read”. So, check your software before you do anything drastic!
RAW files are completely un-edited, they just give you the data straight from the sensor. So, if you shoot hundreds of photos and you want to come straight home and show people, don’t shoot RAW, shoot JPEG.
If you are a landscape photographer like me, and only show a few photos from each few thousand that you take, then consider shooting RAW.
- You will keep all the information from the shot, which helps you correct for any little mistakes the camera (or the photographer) may have made, and helps you get the best possible photo. You should probably invest in some extra computer memory for storing all those large photo files, and maybe a card reader to speed up your photo download speed.
- If part of your photo is too dark or too light, a RAW file will have kept all data, whereas a JPEG may have just called it “black” or “white” and thrown away any extra info. If you shot in RAW, you may be able to get some detail out of the under/ overexposed areas to save your shot.
- If the White Balance or Tint is incorrect, it is completely adjustable. This saves you from carrying grey cards around with you, or constantly having to reset the in-camera balances as you change locations.
So, time for an example. This is a photo I took recently near “The Castle” in the Budawangs National Park near Ulladulla on the NSW South Coast.Now, the photo was taken on a sunny day, under a rock overhang, which confused the camera’s Auto White Balance.
One thing is certain, the answer is definitely not black and white.
By Andrew Carter