Image Resolution for Dummies - The Freelance Files MMCCLVII

Out of focus does not mean low-resolution

As the adage has long told us, "'Close' only counts in horseshoes and hand grenades." That's pretty much true everywhere and when it comes to imparting information, it's spot on. When you ask someone for a definition, you don't want "close": you want "correct." Although many of our nominees receive an award because their work is just plain rubbish, sometimes they get "close." Sadly, that still doesn't cut it. Such is the case of Nicolette Calhoun, who tried valiantly to transfer some technology in the OurPastimes.com post "What Is Considered a Low-Resolution Image?" Well, she got close... sort of.

Calhoun first came to our attention a few years ago when she leveraged her BA in English to school the public on a topic in basic algebra. Now she's back sharing her brand of misinformation on the topic of graphics. Unfortunately, Nicolette's background in photography, computers, graphics and printing left her pretty much bereft of knowledge – much like anyone who depended on her to answer this question.

As is almost always the case, we'll let our nominee's words speak for themselves. Here is a sampling of the bogosity Calhoun barfed up in her quest for an eHow.com stipend:

• "Image resolution refers to the amount of finite detail a photo has." – We aren't certain, but given the context we think Nicolette confused "finite" with "fine."
• "Resolution can be measured in the number of light and dark lines per millimeter or the amount of pixels used to make a photo visible and will often be written on a film camera as LP/mm or in megapixels on a digital camera." – We must admit, we have no idea what "the amount of pixels used to make a photo visible" is supposed to mean, but we know that the "megapixels of a digital camera" is not a camera's resolution but its storage capacity. 

• "An image is considered low-resolution if it uses a small number of pixels to render the image..." – No, Nicolette, it's not the number of pixels, it's the number of pixels per unit area.
• "A single pixel is a small square color dot." – It ain't necessarily color, Nicky.
• "Low-resolution images use fewer pixels than high quality images, and it shows." – Again, Calhoun confused resolution with file size.
• "Scanners and computers use 'dpi,' dots per inch, to render the resolution of images on a computer and on the Internet."  – We hate to have to say this, but you don't "render the resolution of images"; you render the image at a given resolution.
• " A low-resolution image will be much smaller than a high-resolution image. If you render it on a screen, it will appear tiny..." – Sort of correct. If Calhoun had mentioned that the images must be of identical subjects, it would have helped. But she didn't, perhaps because she didn't understand.
• "If you zoom in on the image you will see that the image becomes blurrier or pixilated [sic] the closer you get..." – Actually, a low-resolution image is pixelated (note correct spelling) or blurry when rendered (note correct usage) at the same size as a higher-resolution image.

We thought we'd save the most bizarre claim for last. Under the heading "Spatial Quality," Nicolette "informed" her readers that,

"Some images may have a high number of pixels and a high dpi, but may still appear blurry at a large size. These images have a low spatial resolution. The camera, scanner, or the computer that you are using to render an image, and not necessarily the image itself, causes low spatial resolution. Spatial resolution is measured in ppi, or pixels per inch."

Duh. Spatial resolution is, simply, the size of the smallest object that can be resolved in an image. It's not caused by the "camera, scanner, or the computer that you are using," it's a measure of the real-world area represented by each pixel. Low spatial resolution results from a) a low-resolution image-capturing device or, in the case of a display, image-rendering device; b) an image that covers a relatively large area; or c) both. It's pretty clear from her wording that our Dumbass of the Day had no idea what poor spatial resolution is; as is made obvious by the image she captioned "This image has a low resolution because it has a low spatial quality." In fact, the image (reproduced above) has quite acceptable resolution – witness the large photograph to the soldier's left – but the human being is severely out of focus.

Too bad Calhoun didn't know the difference.

SE - PHOTOGRAPHY