What is the Difference of 8-Bit and 16-Bit Images – Bit Depth and Color Range
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Running Time: 12 minutes
This Digital Fundamentals tutorial is on the difference between editing images in 8-bit color and 16-bit bit depth. While it should be obvious that 16-bit color is twice as good as the 8-bit color, it just doesn’t seem that way to the naked eye. This is because humans can only see less than 10 million colors. Since 8-bit already exceeds 16 million colors, why in the world do we need to work in a bit depth that moves us into trillions of colors? Visually, they both look the same, why use the higher resolution?
This very quick Digital Fundamentals tutorial is only a few minutes long, but guarantees you will never work in the 8-bit bit depth again! With two adjustments using the levels tool, you will see that using the 16-bit bit depth is the only way to go, if you want to achieve the best results possible.
Once you have watched the tutorial, I am sure you will be convinced. Then what should you do to properly make an 8-bit to 16-bit conversion? Well, thats easy. just go up to the pull down menu and select Image – Mode – 16-Bits/channel. Suddenly, you are whisked away to the wonders of color perfection. But, wait, you ask… what about that part, just below, that says 32-Bits/channel? Why talk about 16-bit when we can clearly select 32-bit and bask in all its glory? Well, settle down there, sparky. One thing at a time. I mean, if 16-bit is already trillions of colors, and can save the example in the video tutorial, isnt 32-bit just complete overkill? I sure think it is. But then again, who am I?
Once we have turned the 8-bit image into a 16-bit image, then we can make all of our Adjustment Layers and save our layered PSD or TIF file. When we want to send the file off to the prepress house, or magazine printer, simply go back to Image – Mode – 8-Bits/channel and save the flattened file for them. At this point, all the color changes are done, so no need to have all that extra data. It was only needed to avoid banding or other color corruption before the CMYK conversion.
So then, why do cameras still work in 8-bit bit depth? This is because 8-bit bit depth is old school, and the only one supported by JPGs. If a camera takes a picture, and saves as a jpg, it is good with 8-bit. It does not need to (or can not) make the extra jump to 16-bit. Don’t forget, we can only see a fraction of the 8-bit bit depth anyway. The issue comes in when we, the retouchers, start messing with things, and accidentally cause the banding. The camera did a good job, the first time around. Cameras that save in RAW format save that data with either 12-bit, or sometimes 14-bit.
Questions and Answers
- What is 8-Bit Depth in Photoshop?
Each Color of an image in RGB (Red, Green, Blue) is created from a gradient from black to white. There are 256 shades of grey between Absolute Black and Absolute White. This means that Red has 256, Green has 256 and Blue has 256. The math is 256x256x256=16.7 Million Colors possible. However, it is actually possible to see the 256 shades (steps). If you can see them, it is refrerred to as banding.
- What is 16-Bit Depth in Photoshop?
It is the same as 8-Bit, except that you now have 65,536×65,536×65,536=281 Trillion Colors. Now, I am sure you can image that with only 256 shades of grey, you can see the banding (sometimes). With 65,536, banding has been eliminated as a possbile limitation in your images.
- Why use 16-Bit in Photoshop?
To Avoid Banding. - Which is better, 16-Bit or 32-Bit Depth?
Obviously, 32-Bit will hold many more colors. However, it is this author’s professional opinion that 32-Bit Depth is overkill, and leave you with huge files with little benefit. If you add a few adjustment layers, it can bring your computer to a severe slow down. Also, 32-bit removes options for just about every filter, and adjustment layer. This was only corrected with Photoshop CC v14.1 or later. - Should CMYK be 8-Bit, 16-Bit or 32-Bit Depth?
You can work in 16-Bit RGB, but since CMYK is the last step before sending the image to a printing press, it may as well be 8-Bit. Banding will need to be addressed then. - Why does Photoshop default to 8-Bit Depth, when 16-Bit is better?
The best reason is that several of the Filters, and 3rd Party Plug-Ins only work in 8-Bit. The better question is “Why isn’t there a Preference to Default to 16-Bit Depth?” Also note, as I previously mentioned, Photoshop CC v14.1 corrected the filter issue. So now, there really isn;t any reason for 8-bit, except for saving JPGs. - When should I use 8-Bit Depth Images?
There are a few times when 8-Bit is needed; JPGs can only be 8-Bit, when you need to deliver samples to your client, several Filters are only 8-bit (fixed in cc v14.1), and when you need to convert a file to CMYK for a printing press. These are just examples off the top of my head, I am sure there would be some more.
This Digital Fundamentals Tutorial answers the question: What is the difference between 8-bit and 16-bit, bit depth? If you would like to learn more about Photo Enhancement from a Professional Retoucher, I offer Adobe Photoshop Classes. Please contact me today, and I will be able to add you to the schedule too. If you would just like to watch online videos, The Art of Retouching Studio offers many Photoshop Tutorials for Beginners and Advanced users.
