Digital Photography Hacks [Electronic resources] نسخه متنی

Hack 47 Judge Image Sharpness by File Size

With a series of photographs of the same
subject in hand, you can judge which shot is sharper without ever
opening a file.

Figuring out which photo in a series is the
sharpest can be a laborious task. If you have five shots of the same
subject, you typically open each in turn in the image editor, examine
them all closely, and then make a judgment call as to which one is
the keeper.

If you have to work quickly, this approach can be quite frustrating,
not to mention time-consuming. There's got to be an
easier way! And indeed there is.

You can make solid judgments about image sharpness without ever
opening the file. Both Windows and Macintosh computers provide you
with all the information you need by simply opening the folder that
contains your pictures and viewing some of their basic data.
Eyeballing sharpness is all a matter of sizefile size, that
is. The larger the file, the sharper the picture.

When you're shooting in JPEG mode with your digital
camera (which you usually are, unless you explicitly switch to TIFF
or RAW), the files are compressed in the camera so that they
don't take up too much room on your memory card.
Fine, sharp detail is harder to compress than softer, duller images.
So, the resulting file for a slightly sharper image will be a little
bigger.

Under Windows, open the folder of images and choose the Details view,
as shown in Figure 5-1. In the Size column,
you'll see how big each image is. In this
example, IMG_1005 and
IMG_1006 are of the same subject, but
IMG_1006 (1,803 KB) is a little sharper than
IMG_1005 (1,775 KB). Windows enables you to
preview the image in the Details box in the left column. All you have
to do is click once on the filename, and the preview for that file
appears. This makes it easy to make sure you're
comparing pictures of the same subject.

Figure 5-1. The Details view in Windows

This process on Mac OS X isn't much different.
Choose Column View, as shown in Figure 5-2, and
click the image you want to examine. Finder will generate a
thumbnail, along with the image's file size and
other details. Click another image to compare. Again, file size
should inform you which shot in the series is sharper.

Figure 5-2. Column View in Mac OS X

This hack assumes that you usually shoot more than one frame for each
subject; I highly recommend this. For people shots, I always shoot at
least two frames, just in case someone looks away, closes her eyes,
or otherwise contorts her face in one of the shots. But even for
landscape and other nonpeople compositions, I shoot more than one
frame and then choose the absolute best version of any subject. I
don't hold the camera as steady for every shot. And
sometimes, things happen in the background that I
don't notice in the camera's small
LCD monitor.

Multiple shots ensure that I come away with the best picture
possible. And if you can get away with finding the sharpest version
without opening a single file, why not do so?