Why not just always scan at 48 bit, right?
Well, once you understand the difference between 24 and 48 bit scans, you'll know which bit is best for you.
So, sit back. Grab your favourite drink. Put on some jazz (or not). And let's go!
When I first started scanning, I had no idea what bits were. I thought they had something to do with the resolution.
But after 10 years of scanning for a living, I figured it out... bits have NOTHING to do with resolution. Bits are about COLOUR.
So let me show you an EASY way to know what a bit is. Once you know this, then you'll know when it's best to use 24 or 48 bit. And you won't be wasting your time with your scan project.
Your digital photos are made up of 3 channels: Red, Blue, Green. Let me show you...
Now, when you add up all three channels, you get full colour.
R+B+G = Full Colour...
So? So what if scans have 3 channels? What does this have to do with 24 or 48 bits?
Remember I told you your scan has 3 channels. RBG. When you scan at 24 bits, what you're doing is putting 8 bits per channel.
Let me show you what I mean...
When you scan at 24 bits, each channel gets 8 bits. I know it's a bit confusing. But keep reading, and it will all make sense... soon!
What about 48 bits? Here's what happens...
We're almost there. But I want you to know that this part is important. Because what I'm going to show you will all make sense now.
When you scan at 24 bits, you're going to have LESS bits per colour channel. And when you have less bits per colour channel, you have LESS colours to work with.
Let me show you...
At 24 bits, each channel only get 8 bits. In other words, LESS colours to fill in the pixels. So you get a less smooth gradient, like the image above.
But when you use 48 bits, each channel gets 16 bits. This means your scan colours will look a lot smoother. Like this image below...
Let's zoom in at the pixel level, and compare...
A 48 bit scan has more colours to use. So that's why it looks smoother.
I have a confession. See the images above? They're just simulations. Why? Because the problem with 48 bit scans is you CANT see it.
What do I mean you can't see 48 bit colour?
Let me explain...
The reason you can't always use 48 bit scans is because of two problems...
Problem 1: Our Monitors Suck
First off, most monitors only display 24 bits. That's why you can't see 48 bit colours. Technically it's there. But since our monitors only display at 24 bit, 48 will be "dumbed" down to 24.
It doesn't matter if you have a 48 bit scan, because your monitor won't be able to show you 48 bits!
It's like trying to play a Blue Ray movie on an old standard definition TV.
The old TV can't display Blue Ray quality. It will only show you the movie as standard definition. It will "dumb" down HD to SD.
Same with our monitors. They won't display 48 bit... only 24 bit. So if you ever tried comparing a 48 bit vs 24 bit scan, you can't see a difference... both images will be displayed at 24 bit.
Problem 2: You Can't Scan JPEGs at 48 Bit
So you setup your software for 48 bit. And save your scan as a JPEG. But if you save your scans as JPEGs, they will be converted down to 24 bit.
Because, remember I told you about RBG channels? And a JPEG can only have 8 bits per channel. For a total of 24 bits (8 bits x 3 channels = 24 bit colour).
So even if you setup your scan software for 48 bit, your JPEG will be "dumbed" down to 24 bits.
The reason is because JPEGs are a “compressed”.
What I mean is, a JPEG removes all the stuff you don't need (like extra colour bits). And gives you a smaller file size.
A smaller file size means you can open and view your digital images faster. And if you've ever tried to view TIFF or RAW images, you know how slow it is to load them up.
So if your monitors can't display 48 bits, and JPEGs can't be saved at 48 bit... then what's the point?
1. Printing. If you print a 24bit JPEG it's going to have that gradient affect. Remember I showed you this image...
If you're printing a 48 bit TIFF scan, you won't have this gradient colours. But if you printed a 24 bit scan, and tried to blow it up, you'd get these weird blocky colours.
That's why if you ever go to a professional print shop, they always ask you for a file size. They don't care if your scan is 4000 DPI or 300 DPI. They only care if it's a RAW image that is a certain file size.
2. Editing. Because 48 bit scans are larger in file size, you have a lot more digital information to work with. So if you're doing any editing for magazines, print ads, movies, it's best to work with 48 bit TIFF or RAW scans.
3. Future Proofing. You never know when they'll finally come out with at 48 bit monitor screen!
Good job! The reason I wanted you to learn all that technical stuff was so you DISCOVERED something new. What I mean is, I could have just showed you the step-by-step tips you see below. But then you'd just be copying. And when you just copy, you don't fully understand what's going on. So good job.
Now that's done, let's get to the how-to!
It doesn't matter what scanner you're using. Every scan software will give you the option to pick 24 or 48 bits.
Here's a step-by-step how-to...
Step 1: Pick Your Image Type To 24 or 48 Bit
Don't see this option? If you're using a demo version of some scanning software, they will remove this option for you. Want 48 bit? They you'll have to pay them.
Or, you may have to setup your software to save as TIFF / RAW. See next step...
Step 2: Make Sure You're Saving Your Scans As TIFF If You Want 48 Bit
If you are saving your scans a JPEGs, you won't be able to use 48 bits.
Remember, JPEGs only use 8 bits per channel (8 x 3 = 24 bit colour).
Here's how to change the file type from JPEG to TIFF...
Find the "File Save Options". From there you can choose your file type: JPEG or TIFF / RAW.
Under the save options, you can pick your file save type.
And select TIFF or RAW or NEF – depending what scanning software you're using.
Next I want to give you a system to help you decide when to scan 24 or 48 bit.
Use this system to help you decide when to scan at 24 or 48 bits.
1. Will You Be Printing Or Editing Your Scans?
If YES, use 48 bits TIFF scans. Remember how I showed you that 48 bits has a smoother colour gradient? If you re-print your scans bigger than 4x6, and they are JPEGs, you will get that choppy colour gradient look.
And if you're editing a scan for a movie, magazine, or personal use, it's best to use 48 bit. It has more digital info to work with. What do I mean when I say "digital info"? Well, image editing software will give you more options or tools when it knows its a 48 bit TIFF / RAW image. When you have a simple 24 bit JPEG, you won't see some options or tools.
2. Will You Only Use Your Scans On Monitors, Websites, Tablets?
If YES, use 24 bit JPEG scans. Remember, every monitor displays only at 24 bits. So even if you scan at 48 bits, you can't see the difference because your monitors is limited to 24 bit.
Also, a 48 bit scan will be around 100MB. Think about that. 10 scans = 1 gig! And a 100MB image file is very slow to load on your computer. Plus, forget about using RAW or TIFF scans on the web... they're too big.
3. Want To Future-Proof Your Old Slides, Negatives, Photos?
Ok, so you know that your monitor can't display 48bits. But what if in the future they will?
Or maybe you don't care that a single scan is 100MB and you have a lot of storage space?
Or maybe you'll scan them at 48 bit TIFFs. Back those scans up. And make JPEG copies of each scan so you can use on the web or computer?
Maybe you're a geek like me – you'll scan at 48 bit TIFFs, make a JPEG copy, and be happy that you've future-proofed your scans!
Which of these scanning troubles do you want to overcome?
Hey, my name is Konrad. I've been scanning professionally since 2005. I've helped multi-billion dollar companies, pro sports teams, pro photographers, artists, museums, book publishers, etc. I've scanned over 930,000 slides, negatives, photos.
The reason I'm telling you this is because no matter what challenge or frustration you're having, I know exactly what you're going through. So, to help you RIGHT NOW, I've put together a super simple scanning guide to get you started.