Difference between 48 bit and 24 bit scans

What's The Difference Between Scanning 24 Bit vs. 48 Bit?

After reading these scan tips, you'll discover...

  • Up-close comparison between 24 bit vs. 48 bit scan
  • When should you use 24 or 48 bits when scanning
  • Why your scanner won't let you use 48 bit on some scans
  • Why 48 bit scan may look WORSE than 24 bit scans
  • A non-technical way to understand bits and bytes (with as little math as possible!)
  • Use this “Scan Bit System” to help you decide when to use 24 or 48

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!

Bits Have NOTHING To Do With Resolution and DPI

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.

Why Does Your Scanner Use 24 Or 48 Bits Anyway?

Your digital photos are made up of 3 channels: Red, Blue, Green. Let me show you...

Every digital image scan has 3 channels, RBG

Now, when you add up all three channels, you get full colour.

R+B+G = Full Colour...

Every digital image scan has 3 channels.,, add them up, and you get full colour

So? So what if scans have 3 channels? What does this have to do with 24 or 48 bits?

That's next...

What You Get When You Scan At 24 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...

Digital image scans have 3 channels, and a 24 bit scan will have 8 bits per channel

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 You Get When You Scan At 48 Bits

What about 48 bits? Here's what happens...

Digital image scans have 3 channels, and a 24 bit scan will have 8 bits per channel

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.

What Does 24 Bit Scan vs. A 48 Bit Scan Look Like?

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...

A 24 Bit JPEG scan will have less smooth colours

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...

A 48 Bit TIFF scan will have more smooth colours

Let's zoom in at the pixel level, and compare...

24 bit scan vs 48 bit scan zoomed in

A 48 bit scan has more colours to use. So that's why it looks smoother.

Hold on!

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...

Problems With 48 Bit Colour Scans

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.

All monitors, tv, tablets display at 24 bit colour

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.

You can't display full hd quality on old standard definition tvs

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.

JPEG scans are only 24 bit not 48

Why?

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).

Digital image scans have 3 channels, and a 24 bit scan will have 8 bits per channel

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?

That's next...

So When Is Scanning At 48 Bits A Good Idea?

1. Printing. If you print a 24bit JPEG it's going to have that gradient affect. Remember I showed you this image...

A 24 Bit JPEG scan will have less smooth colours

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!

Hard Part Is Over... Let's Talk About When To Scan At 24 or 48 Bit

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!

How To Setup Your Scanner For 24 or 48 Bit Colour Images

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

Your scan software will give the option to pick 24 bit 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...

Your scan software will have file save options so you can save as jpeg or tiff raw

Find the "File Save Options". From there you can choose your file type: JPEG or TIFF / RAW.

Under save options, you can pick your file save type when scanning

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.

“Scan Bit System” -- When To Use 48 Bit Or 24 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!


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  • Best method to digitize slides, negatives, photos using your regular flatbed or film scanner
  • How to clean your negatives, slides, and photos before you scan them -- so you don't scratch them
  • What side should you scan a slide or negative -- so they're not backwards or facing the wrong way
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  • How to fix your digital images using Digital ICE, GIMP, or Photoshop and make them look new
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  • Understand the technical stuff of a digital image so you can make sideshow videos, reprints, and more!

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.

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