Evaluate Image

A Quick and Dirty Guide to Evaluating Your Portrait Picture for Enlargement

GIGO – Garbage in, Garbage Out.

It’s an old computing term. It means that if you put bad (garbage) data into a computer, you’re going to get bad (garbage) data back out. It’s kind of like that with images. People send us Polaroids all the time, wanting to know if we can turn them into beautiful posters. We can turn them into posters all right, but they won’t be any more beautiful at 6 feet by 6 feet than they were at 3 inches by 3 inches—in fact they’ll be worse, because whatever tiny little microscopic flaws that existed in the original Polaroid shot will be three INCH flaws at poster size. And there’s the lack of data to consider. We can do all kinds of stuff to make bad images look better. We have all sorts of custom interpolation routines which help, and we know many tricks which must be applied manually. But in the end, it’s still mostly a matter of GIGO. The best bet for ending up with a beautiful custom poster is to start with a really good original. We don’t particularly like 35mm film. It’s kind of a “consumer size” film. On top of that, folks tend to want to use films like ASA 400, but regardless of what they told you at the camera store, you’ll get crappy images from it, especially if enlargement is your goal. And it should be illegal to take any photograph without a tripod. We cringe when we’re asked to take a 35 mm shot beyond an 8 x 10 inch print size. We’ll do it of course, but it makes our toes curl. On occasion we are supplied a good, crisp, professionally shot 35 mm negative which we can tweak and romance and interpolate and adjust and squeeeeezzzzeee….and get an acceptable (not great) “C” size (17 x 22 inch) print. But mostly 35 mm is limited to 8 x 10 at best. We like working with 220 negatives, or larger — even 4×5 or 8×10 negatives. Having said all that, what’s “acceptable” or not, is very subjective. We’ve enlarged 5 x 7 prints to poster size and we almost refused to send them out. But the customer was tickled. There’s no accounting for taste. What’s blurry and worthless to us might look fine to the new mom who’s in love with her infant. But here’s something tangible you can use to evaluate your own photos for possible enlargement. It’s quick and dirty, but it’ll get you on the right track.


The image on the left was taken with a 35mm camera, and the image on the right was taken with a digital camera. But that makes no difference! It could just as easily be the other way around, depending on the lens, lighting, focus, what-have-you. What we’re examining here is the clarity of the image, regardless of what it was captured with.The procedure is simple: Grab the image you’re thinking of having enlarged and look at it with any old magnifying glass. An eye is one of the best features to use for evaluating clarity. If the eye in your image looks like the picture on the left, toss it. We’ll enlarge it if you want, but it will look terrible at anything larger than 5 x 7, and in fact it will look poor at 5 x 7 too. In the case of the image on the left, the owner started out with a 5 x 7, but took it in to the photo finisher and had it blown up to 8 x 10, thinking that would solve the problem. Of course he just ended up with a much larger blurry eye.

But if the eye in your image looks like the image on the right, we’ve got some clarity to work with. This is still not a “great” image for clarity, but it’s acceptable for government work, and with some tweaking, we can probably get the entire image (which includes this eye) to plump up to, say, “C” size or even larger, depending on how much clarity you’re willing to lose to get the size you want. Any image which features an eye of like-clarity as the image on the right would make a nice 8 x 10 inch portrait—and probably larger. Rule of Thumb: If you can count, or almost count the eyelashes or the hairs of the eyebrow, there’s enough clarity to work with.

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