“Before You Go Buy That Expensive Scanner, Read This First” Part 2
So, now you know what side to scan. Great. Next lets find out what resolution to scan at. Resolution is kind of confusing, and I’ll throw around a few numbers, but I won’t get too technical.
First, DPI or PPI:
DPI = dots per inch, PPI = pixels per inch. They’re the same thing. The print industry uses dpi, and the hard core graphic designers use ppi to sound smarter. But it’s the same thing.
So? What’s the big deal with dpi?
DPI has nothing to do with the quality of the image. It just tells the computer to put 72 dots per inch, or 300, or 4000. When it does that, it’s not picking up detail… it’s not going in “further” in the photo and picking up minute, say, creases in your jacket to make the image sharper. It’s just taking more info to make a bigger image. So, if you’re scanning at 4000 dpi, all you’re doing is taking the same quality image but making it bigger. That’s all.
Let’s actually compare. Here’s the photo I’m working with.
And here’s a close up comparison: 72-dpi vs. 300-dpi vs. 600-dpi.
See that? Did dpi sharpen the image? Did it make it a higher quality scan? Did it save the day? No. Higher dpi just means your image will be bigger. Which is not a bad thing of course. Say you want to do some editing, the more info you have, the better. But, just don’t buy into thinking that higher dpi means better quality. In fact, anything after 600-dpi you’re losing quality. Let me explain.
When you get your photos developed, they are at around 300-dpi. So when you scan that photo, you’re not going to pickup any more detail than 300 dpi. Once you start going over 600 all you’re doing is now scanning the surface of the photo film, the texture, the gloss, etc. You’re no longer picking up the image, you’re just scanning minute scratches, dents, finger prints on the photo surface. Just look at my 1200-dpi scan, close up:
If you look closely, you can start seeing the vertical lines from the printer itself; a smudge; and it’s starting to pick up the gloss off the surface of the photo.
So, what’s the best resolution? Here’s what I do. Again, I’m using the Epson V500 Photo scanner, but that doesn’t matter because you’re scanner software will have the same buttons I have.
Here’s how I setup my setting for photos:
Keep the resolution at 300-dpi, don’t touch that. What you do change is the Output Size, or Target Size. See, my photo is 6″ wide, and 4.13″ height. I scan, 4×6 @ 300-dpi.
Why 4×6 @ 300-dpi? Because even today’s 52″ HDTV’s have almost the same resolution. I might want to scan at 8×12 @ 300-dpi if I’m doing any re-printing, or even 16×24 @ 300-dpi, but only when I’m doing editing for commercial use. Other than that it’s just over kill.
What about slides and negatives. Same thing. I keep the dpi at 300 and change my output to 4×6.
Before we finish, lets compare a 4×6, 300-dpi scan to your 52″, 1080p HDTV.
So, how do they get the 1080p, what does that mean? I’ll show you:
Your 1080p HDTV is really 1080×1920 pixels. A 4×6 scan is 1200×1800 pixels. How do you get that?
Math:
Multiply 300-dpi by 4″: 4 x 300 = 1200
Multiply 300-dpi by 6″: 6 x 300 = 1800
That’s how you get the 1200×1800.
And, do you want to know how you get Mega Pixels?
Multiply 1200×1800 = 2.1 million. So, 2.1 mega pixels.
Ok, resolution is important, but not to get a quality scan. How you get a quality scan is all about “post processing”. But if you have a simple home scanner, and you’ve tried “Digital ICE” or “Colour Correction”, or any other fancy names they give it, you know that it doesn’t work that well. Next post I’ll show you how, with a few buttons, you can tweak the post processing so you get an excellent, high-quality image scan.
Onto Part III: Click Here
