Image Resolution: Making Pixels Count

For some of us, there is a bit of confusion surrounding the issue of image clarity. For those that don’t understand the impact that image resolution has on a final product, getting the image results you dreamed of could turn into a headache. Lets say you download an image of the internet. On your monitor, the image looks sharp, clear and perfect, but when you printed it out what you get is definitely far from presentable. This situation is common, but you can’t blame the image’s creator for the problem, the issue is that the photo you saved and printed is low resolution, and unless its a file you made yourself, making a high res version out of a low res file is near impossible.

What is resolution?

In order to understand why resolution is important in printing and publishing, you first need a general grasp of what the term resolution actually refers to. Image resolution is an important aspect of image printing. Resolution refers to the amount of image detail that the image hold. This information is most often stored within the pixels an image contains, which translate to dots of individual color within a complete image. Think of a traditional newspaper print. Looking closely, you can see the individual dots that make up that image. In the same vein, an image with more dots, or a higher resolution image, will look clearer, sharper and contain more detail. This concept however, only applies to the image when it is printed. The resolution of an image has nothing to do with how the image appears on a computer screen. It does, however, have everything to do with how an image will print.

Web vs. Print

Because there is little import on the number of pixels that are display on a screen, the web has a tendency to use smaller images to reduce file sizes and speed up upload and loading times for web pages. As a result, most web images range around 600 x 600 pixels, meaning that with a standard image at 640 pixels wide by 480 pixels high there are a total of 307,200 pixels available to display color information. For this reason, most web images are unsuitable to use in print projects, and business owners often find it hard to use their existing images for new print campaigns without access to the original files.

Most digital camera however can take much higher resolution photos, with some newer smartphones, such as the Galaxy 4s, taking photos at a whopping 13 Megapixels. This means that an image taken with this phone will have a whopping 13 million available pixels of color, allowing for rich colors and sharp details. These images will also be considerably larger in file size.

Why 320?

For anyone who has ever attempted to resize an image in photoshop, or submit a file for printing has come across a need to define (or at least notice) image resolution. As we mentioned earlier, resolution only matters when you print an image, and here is why. Let’s say you set your resolution to be at 72 pixels/inch. This means that for every square inch of your image image, when you print the photo, 72 pixels will be printed from left to right in our photo (the width), and 72 pixels from top to bottom in our photo (the height) will be printed for every one inch of paper. Using a standard web image of 640 x 480, you image will max out at 8.8 inches wide and 6.6 inches tall. Anything larger than that would begin to look pixelated and unclear.

Most printing places request a resolution of 320 because it allows for enough color data to be stored within the image to print a sharp and clear image, regardless of size, however specifically for larger printed items such as banners and large photos. With a file this size, printers can be sure that there is no loss of detail in the large print, and ensure that what you see as a final product looks the same as what you saw on your screen.

If you’re interested in finding out more about how print resolution works for specific print sizes, urban75, an online photo magazine and forum has a great list. Countless tutorials can also be found on the web about manipulating resolution.




Category: Printing