Do You Want Resolution or Quality?

It can be easy to confuse the resolution of a JPEG image with its quality. They're not exactly the same, and you'll want to pay attention to both. In this article I'll explain why.

Resolution is About Pixels
The total number of pixels in an image determines its resolution, or the ability to show fine detail. In a low resolution image with fewer pixels, they are readily seen and the detail is obscured. In a high resolution image with more pixels, the fine detail becomes visible and the image appears sharper. You'll have a better image with more resolution.

Many digital cameras give you a choice of image size, or the number of pixels recorded. The highest resolution setting may be labeled "Large" or "Maximum" and will yield the largest pixel width and height. Use this setting when photographing your artwork to get the best images.

But here's where the confusion comes in. There may also be a "Quality" setting on your camera, and it's different than the resolution setting.

... Quality is About Compression
When a JPEG file is saved, you may have a choice of image quality, or how much it is compressed. This setting is important because image detail is lost as an image is compressed more. And once detail is lost, you can't get it back later.

This loss of detail happens because the compression algorithm used for JPEG files is "lossy". All of the pixels in the original image are still there, but adjacent ones with similar colors are treated as if they had the same color (this is how the file is compressed). The example here illustrates how compression changes pixel colors. The more a file is compressed, the more pixels are treated as having the same color, and the more detail is lost.

In other words, there is a trade-off between JPEG quality and file size. Less compression makes for a larger file and a higher quality image, while more compression gives you a smaller file but a lower quality image. On your camera, the lowest compression setting may be labeled "High Quality" or "Superfine" and will yield the largest file size. On the computer, the lowest compression in Photoshop® is "Maximum Quality" or the highest numbered quality setting.

Where's the "Sweet Spot"?
When shooting your artwork, always set your camera to the highest resolution (the most pixels) and the highest quality (the least compression or largest file size). This will give you the best image as your digital "original". Later, when you save the image for emailing or uploading, you can resize it (with fewer pixels) and compress it (with lower quality and a smaller file size) as appropriate for the planned use. At the "Medium" or "High" quality settings in Photoshop®, you'll get compact files that look great on any computer screen.

So, do you want resolution or quality? The answer is both.

And click here to learn more about the JPEG format in the Learning Center at ShootMyArt.com™.

Just the Pixels, Ma'am

I explained in my last article why DPI (Dots Per Inch) doesn't matter for most of what you'll do with images of your artwork. So what does matter? Well, as Sgt. Joe Friday from Dragnet might have said, "Just the pixels, ma'am".

Only Pixels Count
The total number of pixels in an image determines its resolution, or the ability to show fine detail. In a low resolution image with fewer, the individual pixels are readily seen and the detail is obscured. In a high resolution image with more, the fine detail becomes visible and the image appears sharper. It's that simple ... more pixels equals higher resolution.

The resolution of an image is often described in millions of pixels, or megapixels. Camera manufacturers have steadily improved sensor technology, and inexpensive consumer cameras today produce images with 6-8 megapixels. Unfortunately, we've been convinced we need all those pixels, even though it's often more resolution than we can use. A good 4" by 6" print, for example, needs only 2 megapixels. And your computer screen needs even fewer.

... But Not Too Many
When an image is displayed on a screen, each pixel on the screen displays one pixel from the image. A common screen size today is 1,024 pixels wide by 768 pixels high. That's less than 1 megapixel (the width times the height). If an image has more pixels than the screen, only part of the image will be displayed and you must scroll to see the rest of it. Or, if your software compresses the image to fit the screen, it is throwing away some of the pixels. Either way, the extra ones are just wasted.

Like Goldilocks, you don't want too many or too few in an image, but just the right number. I recommend 800 pixels on the longer side of an image as a good size for juried entries. At that size, your artwork will fill most computer screens without the file being too large. But if an image is to be printed, you'll need more pixels and will want to know both the DPI and the size to be printed.

Gallery Requests Revisted
With all of this in mind, let's take a look at several recent requests from galleries for images.

“Save images as jpegs, at 300 DPI.” Wrong ... you didn't specify the image size in pixels, and DPI doesn't matter, so I don't know what you'll get.

“Images should be approximately 800 x 600 pixels at 72 DPI.” Excellent ... you'll get exactly what you want (but skip the DPI next time so you don't keep the myth alive).

“Suggested minimums: 800 pixels in either direction at 150 DPI.” Good try ... but what's the maximum size (and 150 DPI doesn't make it medium resolution).

So as the announcer says at the end of Dragnet, "The story you have just seen is true. Only the names have been changed to protect the innocent." Don't you be one of the guilty.

And click here to learn more about resolution in the Learning Center at ShootMyArt.com™.