One of the biggest problems many of us face with digital photography is trying to print an enlargement and have it look decent. What looks fine on the screen can come out blurry, blocky, or at least lacking in detail, when printed. What is the best method to resize your photos to be larger (and have more pixels)?
Also, sometimes you just don't have enough zoom and/or not enough megapixels in your camera, and you wish to salvage
what you can out of what you have.
Below is a comparison of several methods of enlarging photos digitally. They are kind of large, so you may have
to scroll around to see everything, but I wanted to try to preserve enough detail to be useful.
Here's a photo of a stunt plane that I took at a local air show. (Great show, by the way, if you're into planes!) It's not the best example not only because I don't have enough pixels, but because the plane was moving, I was handholding the camera, and to top it off, it was an overcast day. This discussion is concerned more with increasing the number of pixels to improve print detail. Let's pretend I still want to hang this on my wall even with all of its negative attributes. :-)
This is a 400% resize using bicubic interpolation (and Paint Shop Pro 7 by JASC). Note the jagged lines around
all of the edges. It's enlarged, but it is not looking so good!
This is 400% resizing using Genuine Fractals. Note the "painterly" effect. What is nice about this technique
is how sharp the lines are, but everything looks a bit fake.
This is a 400% resize using Lanczos interpolation (using the free IrfanView software!). Note that the jaggies are
gone, and it still looks like a photo and not a painting.
But, what if you like that sort of painting effect?
This is the Lanczos enlargement, but brought into Paint Shop Pro and given a "smooth preserving lines"
effect, plus a tad of sharpening. What's nice about this is that you can adjust the amount of smoothing to your
taste.
I've seen it said in multiple places on the 'net that you can achieve superior results by using Photoshop's bicubic resize, but only do it incrementally, by a small percentage, and repeat that over and over. I used Photoshop Elements 2.0, and resized by 102% many times until I reached this size. In my opinion, this is a mess. It shows signs of "ringing" around edges, and has amplified the noise. This is the same look you'll get if you overdo the sharpening. The same thing has happened with other photos I've experimented on.
Perhaps someone will let me know if I'm missing some crucial part of this technique!
(click for a larger view or to see more detail)
All of the previous photos suffered from too much noise, which was simply magnified when the original was resized.
Some of the noise was due to the conditions (possibly high ISO, the normal noise you get in JPEG compression).
In Paint Shop Pro, I enhanced the contrast slightly (with the Histogram function), punched up the color slightly
(with the saturation tool), ran the "JPEG Artifact Removal" function (set to Normal), and then the "Line-Preserving
Smooth", all before any resizing, in order to make the source as clean as possible. The result is a pretty
clean enlargement that might look a bit soft, but looks much cleaner even up close. If it's not going to be viewed
too closely, this much work might be overkill. I printed it at about 5"x10", and I think it's pretty
decent considering what we started with! I suspect a slight amount of detail is lost with each processing, but
this is just a judgement call as to whether or not it's worth it.
If you can, try to use the least amount of JPEG compression, or for those special shots, try TIFF mode (but you'll
get huge files!). However, you'll have a much cleaner source, and enlarging will work more effectively. If you're
not going to enlarge, JPEG is pretty efficient, so most of the time, don't be afraid to use compression, particularly
as you run low on memory. Most of my shots will never be printed large.
In my opinion, the Lanczos interpolation looks like it is superior. It looks like you blew up a grainy photo, which you kind of did. It seems to be a bit more natural and more smooth. My biggest gripe is that I typically use Paint Shop Pro and Photoshop Elements, neither of which support this method, so it is more difficult to work with. With most of these methods, if you step back far enough away from the photo, it will look like a photo, so it may just come down to your personal preference as to which technique you prefer. Experiment! Print some enlargements, and take a few steps back from them while viewing.
Meanwhile, I do not often find a need to resize my photos. Even 8x10's look decent from my 3 megapixel camera,
and I'm not too worked up over wringing out that extra 2% improvement. However, I occasionally get stuck trying
to do a "digital zoom" to salvage a photo (such as the air show photos where I couldn't get any closer!),
and would like to get what I can out of it. For those of you who want a more automated way to get the Lanczos interpolation,
look into Qimage Pro. I have not used it, but the author has an excellent comparison of his own.
Having said all of that, I do like Genuine Fractals, because in many instances, the painting effect looks good.
The image still looks "sharp" with sharp edges -- you do not need to sharpen a photo after using Genuine
Fractals. You can then combine this with other artistic filters, such as watercolor, etc. My advice is to have
fun experimenting!
Gary Wolfe