Benefits Of Working With 16-Bit Images In Photoshop

What Does The Term "8-Bit" Mean?

You may have heard the terms 8-bit and 16-bit before, but what do they mean? Whenever you take a picture with a digital camera and save it in the JPEG format, you're creating a standard "8-bit" image. The JPEG format has been around for a long time and as digital photography and even Photoshop itself continue to advance, the limitations of the JPEG format are becoming more and more apparent. For one thing, there's no way to save a JPEG file as 16-bit because the format doesn't support 16-bit. If it's a JPEG image (with the extension ".jpg"), it's an 8-bit image. But what does that mean, "8-bit"?

If you read our tutorial RGB and Color Channels Explained, you know that every color in a digital image is made up of some combination of the three primary colors of light - red, green and blue:

It doesn't matter what color you're looking at on your screen. It's being made up of some combination of those three colors. You may be thinking, "That's impossible! There's millions of colors in my image. How can you create millions of colors out of just red, green and blue?"

Good question. The answer is, by using multiple shades of red, green and blue! The more shades of each color you have to work with and mix together, the more colors you can create. If all you had was pure red, pure green, and pure blue, the most you could create would be seven different colors, including white if you mixed all three together:

You could also include an eigth color in there as well, black, which you would get if you completely removed red, green, and blue.

But what if you had, say, 256 shades of red, 256 shades of green, and 256 shades of blue? If you do the the math, 256 times 256 times 256 equals roughly 16.8 million. That's 16.8 million colors you can now create! And that's exactly what you get with an 8-bit image - 256 shades of red, 256 shades of green, and 256 shades of blue, giving you the millions of possible colors you usually see in a digital photo:

Where does the number 256 come from? Well, 1-bit equals 2. When you move beyond 1-bit, you find its value using the expression "2 to the exponent (however many bits there are)". So, for example, to find the value of 2-bits, you would calculate "2 to the exponent 2", or "2 x 2", which equals 4. So 2-bits equals 4.

A 4-bit image would be "2 to the exponent 4", or "2 x 2 x 2 x 2", which gives us 16. So 4-bits equals 16.

We do the same thing for an 8-bit image, which would be "2 to the exponent 8", or "2 x 2 x 2 x 2 x 2 x 2 x 2 x 2", which gives us 256. That's where the number 256 comes from.

Don't worry if you found that confusing, or even worse, boring. It all has to do with how computers work. Just remember that when you save an image as a JPEG, you're saving it as an 8-bit image, which gives you 256 shades each of red, green, and blue, for a total of 16.8 million possible colors.

Now, 16.8 million colors may seem like a lot. But as they say, nothing is big or small except by comparison, and when you compare it with how many possible colors we can have in a 16-bit image, well, as they also sometimes say, you ain't seen nothin' yet.