An Easy Way To Understand Scan Image Resolution

In this article, you're going to...

  • Finally understand what resolution is and is NOT
  • See how to setup your scanner's resolution for slide scanning
  • Learn how to use resolution so you can do more stuff with your digital images

If you don't understand resolution, you might waste your time scanning your slides at the wrong resolution.

1. The Only Number You Should Remember Is This...

Forget about DPI, resolution, mega pixels for now. The only number you need to remember is the Pixel Dimension.

Pixel dimension is the width and height of a digital screen or image. The best way to understand pixel dimension is to look at your HDTV. Here's what I mean...

slide scans on a hdtv

A 1080p HDTV has a pixel dimension of 1920 x 1080. What about your other screens? Let's have a look...

screen resolution of hdtv ipad computer monitor phone

You already know your HDTV has a pixel resolution of 1920 x 1080. Here's the pixel dimension of...

Compuer monitor: 1028 x 768
iPad: 2048 x1 536
Mobile: 1200 x 800

2. Other Places You Have Seen This Sort Of Number

Ok, now you know a 1200 x 1800 digital image is just like a 4x6 photograph. Now, what would happen if you put that 1200 x 1800 digital image on your HDTV?

Let's see...

a 1200 x 1800 digital image will fit on your hdtv

Did you know that the digital size of a 1080p HDTV is 1080 x 1920. Does this number, 1080 x 1920 look familiar?

What about your monitor or ipod? It's probably around 1200 x 768. Now, if you displayed a 1200 x 1800 digital image on any of those devices, it will look excellent.

However, if you have an image smaller than 1200 x 1800, it will look stretched and at a lower quality.

Here's the whole point: As long as your digital images are 1200 x 1800 then they will be HD quality.

The reason I'm showing you this number, 1200 x 1800, is because it's the TRUE measure of resolution. This number is your litmus test. This number is your standard. Now, let's tie this in with your slide scans.

3. How Do You Make Sure Your Slide Scans Are At Least 1200 x 1800

Here's what I want you to do RIGHT NOW: place a slide on your scanner, and fire up your scanner software. If you're not sure how, click here to load your slides properly on your scanner.

Here's what my software looks like (don't worry if yours is different, you can still follow along):

slide scan resolution setp

Do you see a spot where you can pick your Resolution or DPI? This is where you control how big your digital image is going to be.

So for fun let's use 300 DPI, and hit the Preview button. Here's what happens...

slide scan at 300 dpi

As you can see I used 300 DPI. And after my Preview, I can see that at 300 DPI, I only get a 387 x 255 digital image. That's way too low. Remember, we want 1200 x 1800. At that size we can print our slides at 4x6 and view them at HD quality.

So let's bump up the DPI to 1500...

slide scan at 1500 dpi resolution

Perfect! At 1500 DPI, my slide is around the 1200 x 1800 mark (my scanner software flips this number, 1800 x 1200.. but it's the same thing).

Now let's use my scanner's full capacity: 4000 DPI. Here's what I get...

slide scanned at  4000 dpi resolution

At 4000 DPI, I get a digital images that's 5000 x 3400. This means I can print my slide as big as 24" x 36". And these images are HD quality of course.

4. So What DPI Is Best For Slide Scans?

If you use 1500 DPI you will be safe. You will get a standard 4x6 digital photo, that is HD quality.

And at 4000 DPI you get a 24x36 digital photo, that is also HD quality.

But hold on, this DPI is only good for your 35mm slides.

What about other size / formats like 120 slides?

5. DPI Cheat Sheet For Every Slide Size / Format


135 Slide (35mm Slide)

35mm slide type

Approx. size in inches: 1.3" x 0.85"
Max resolution you can scan: 4000 DPI
Mega pixels when scanned at 4000 DPI: 18
Pixel dimension when scanned at 4000 DPI: 5200 x 3400

127 Slide

127mm slide type

Approx. size in Inches: 2" x 2"
Max resolution you can scan: 2600 DPI
Mega pixels when scanned at 2600 DPI: 18
Pixel dimension when scanned at 2600 DPI: 5200 x 3400

126 Slide

126mm slide type

Approx. size in inches: 1.04" x 0.98"
Max resolution you can scan: 4000 DPI
Mega pixels when scanned at 4000 DPI: 17
Pixel dimension when scanned at 4000 DPI: 4160 x 3920

110 Slide

110mm slide type

Approx. size in inches: 0.63" x 0.47"
Max resolution you can scan: 4000 DPI
Mega pixels when scanned at 4000 DPI: 5
Pixel dimension when scanned at 4000 DPI: 2520 x 1880

Medium Format Slide Transparency

medium format film

Size and DPI vary.

But use 1200 DPI, and you'll get 24x36 digital images.

Large Format Slide Transparency

large format film

Size and DPI vary.

But use 900 DPI and you'll get 24x36 digital images.

Free Ebook: Tells You Secrets To Getting High Quality Slide, Negative, Photos Scans In Half The Time

Which of these scanning troubles do you want to overcome?

  • What's the best resolution / DPI to scan your slides, negatives, and photos -- so you don't lose details
  • 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
  • How to setup your scanner to get higher quality digital images -- 24bit JPEG? 48bit TIFF?
  • How to fix your digital images using Digital ICE, GIMP, or Photoshop and make them look new
  • How to improve your scan workflow so you can double your productivity and finish your project twice as fast
  • 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.

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.

How to scan slides negatives photos into digital, free ebook download

Your free ebook is up for grabs. Just click the button below and start downloading...