I frequently get asked how to make a small image larger – meaning that
someone has found an image on the internet (typically a thumbnail of some sort)
and want to enlarge it to something bigger.
Unfortunately, image detail that was lost when the image was resized to be
smaller cannot be recovered by resizing it larger again.
In this video excerpt from a recent Ask Leo! webinar on
photo manipulation, I’ll discuss what it all means.
So one of the other questions that I often get is people want to take an image that they found on the web (commonly the scenario) and make it bigger. The image is too small; they want to basically enlarge it so that they could perhaps see more of the details in that image.
What I’m going to walk through here is exactly a) how you would do that, but b) why you’re not going to be happy with the results. So the image that I’m going to use is a familiar one, I hope, to all of you and that is the logo from my website. That image is 78 pixels high, it’s 260 pixels wide, and it is obviously a photograph of my face.
So let’s say that for some reason you wanted that photograph, only larger. You don’t have the original, all you have is this that was taken from a website somewhere. Yes, it is absolutely possible to use the resize function in an image editor (such as FastStone) to say, “Let’s make that image 400% bigger.” So we’re going to take the original 260 x 78 image and make it 1040 x 312. It’ll be bigger; absolutely, it’ll be bigger!
The problem is it won’t be any clearer. The problem is that when an image is resized, information about that image is lost in the process. The information that contains all of the details of the actual thing that you’re looking at (at the resolution that it was originally shot at) is removed; that’s how you make the picture smaller. When you enlarge the small picture and make it larger, there’s no way to add that information back in. What happens instead is that the existing low resolution information is simply expanded to fill the space. So, as you can see, my face here is actually pretty blurry. In fact, I’ll make it even larger; I’ll make it even larger since there’s an opportunity here. I’m gonna go for 800%. So now, you can see … no, we’re actually scaled so I’m going to go to (let’s see, I should be able to hit ‘View’ ) what I’m trying to get it to do is to view it at 100% – there we go, 100%. So, this is the original picture; my little 72-pixel high headshot expanded to be 624 pixels high and as you can see, it’s really blurry. The information that was present in the original got lost when that original was scaled down to 72 pixels and there was no way to add that back in.
Now, what most programs do and I have to admit that FastStone has done a very nice job of this is they apply smoothing algorithms, so that they’re not just giving you 72 pixels where each pixel is now like eight pixels in size or something like that. They actually take a look at the colors and what’s being shown in the image to provide a smoother result than just making each pixel bigger. So actually, it’s blurry; it’s definitely blurry, but it’s actually not bad for having been increased 800%.
So unfortunately, what that means though is what you’re trying to do (by taking a small picture that you find somewhere and increase its size to whatever to enlarge it) to be able to see the details that you can’t see when it’s small is doomed to failure because those details aren’t there in the first place. What resizing does – it’s interesting because when you take a look at a picture like this, you say, “Oh my gosh, it’s blurry. I would never want to use that.” But on the other hand, if you take a look at the original, it seems like it’s a lot better, it seems like it’s sharper; it’s not. It’s an optical illusion. It is the fact that your eyes perceive this to be a smaller picture; it looks like it’s better. As soon as you expand this to fill a larger area, you can now also see imperfections that were in the original photograph.