This Is What Resolution You Should Scan Your Photos
A non technical guide on what is resolution, and how to use it for photo scanning.
Take a look at these numbers: 300 Dpi 1200 x 1800 pixels 2 mega pixels.
Hdtv
Confusing? Do you think I am just throwing numbers at you? All those numbers well mean the same thing. Resolution is confusing. But if you come along, I will show you what resolution is. Once you understand the basics, you will be more comfortable selecting what resolution to use for your photo scans. Here we go.
What Is Dpi Anyway?
Remember back in the day when you had to manufacture your film? You walk into a photo lab and hand the photo lab your film. One hour later your photos were ready.
If you have a physical photo handy, look at it. What that photo lab did was print 300 dots for every inch of that photo. 300 dots of colours are squeezed into every inch.
Dots per inch or Dpi comes from those days when you had to manufacture your film. In your typical photo lab, the printers could only go 300 Dpi. So your 4″x6″ are technically 300 Dpi.
300 Dpi Is adequate For 4″x6″ Photos. So you want to scan your 4″x6″ photo. What resolution should you set your scanner at? Ok, so we know that a physical photo is 300 Dpi. So setting your scanner at 300 Dpi (sometimes they call it Ppi or pixels per inch) will be enough.
But here is a curve ball. Look for something called “output size”. Make sure it is set at 4″x6″. Remember, we want to put 300 dots per Inch. So make sure the yield size is 4 inch by 6 inch. Doing that you know you are putting 300 dots or pixels in for every inch. And if you have a 8×10 photo, set the yield to 8×10 and keep the dpi at 300.
What If You Use 600 Dpi For Photo Scans?
Once you go over 300 Dpi, your scanner will start to pickup stuff you do not want. Stuff like petite hairs, the actual paper, gloss off the photo surface. Why is that?
At 300 Dpi, the scanner already picked up as much information the photo holds. Peoples faces, smiles, eyes, trees, etc. After 300 Dpi, the scanner just picks up information off the physical photo itself. This is because your physical photo only contains 300 dots of “info” or “data”.
People think that at a higher resolution you will start picking up more information of Things in the photo. Not true. The print shop already put as much information it could on that photo. After 300 Dpi the scanner just picks up debris.
So, Why Would You Want More Than 300 Dpi Scans? Let’s look at your photo scan. The yield size is 4″x6″. The Dpi is 300. Lets take those numbers and do something with them that makes sense.
Do you know the resolution of your Hd Tv is 2 mega pixels!? Hold on. All this will make sense. Your Hd Tv, no matter what size, has 1080 x 1920 pixels. That is where they get the 1080 from.
Anyway, your 4×6, 300 dpi photo scan is: 1200 x 1800 pixels. How did I get that number? Magic:
4 inches multiplied by 300 = 1200 6 inches multiplied by 300 = 1800
In other words, 1200 x 1800. Now, when you multiply those two numbers you get, 2.1 million. Or in marketing terms, 2.1 mega pixels!
Same with your Hd Tv. You have 1080 x 1920, or 2.0 mega pixels.
So when you display your 4×6, 300 dpi photo on your Hdtv, it will be in full resolution. Your 300 Dpi photo scan is true Hd on your 1080p Hdtv.
Back to my former question. Why would you want more than 300 Dpi? Back in 1999 I scanned my photos at 72 dpi. That is because all computer monitors were/are 72 – 100 dpi. Back then I never knew monitors would be larger than that. So 72 was safe. Now my 72 dpi scans are useless.
When you scan your 4×6 photos at 600 dpi, you get:
4″ x 600 dpi = 2400 6″ x 600 dpi = 3600
Which is, 2400 x 3600 pixels or 8.6 mega pixels. Even though 300 Dpi is adequate to pick up detail, I still rather scan my photos at 600 or 900 dpi. You just never know what technology is going to come out. And do not be like me, and have to re-scan all your photos again at a higher resolution.
How To Get More information From Your Scans?
Photos have limits. But your negatives, well, they hold over a million Dpi. They hold more information than any today’s scanner can pick up. This is why hard-core expert photographers still shoot with film. No digital camera can pickup what analog can.
In my next narrative I will show you how to scan your negatives– which hold more information than any photo.
Hopefully by now those three numbers I threw at you in the beginning make sense.
This is Konrad. Thanks for reading!
This Is What Resolution You Should Scan Your Photos
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