Learn Photo Basics #6 – Resolution

Understanding Resolution in Digital Photography

Resolution is a common word when you enter the digital photography realm. It can be a tricky and confusing topic, as each item in the photographic chain has its own relative resolution value that isn’t interchangeable with the next item. But once you understand what is being measured, you can plan accordingly.

Camera and Image Resolution

Image Resolution

Millions of pixels that make up the image sensor in a digital camera are actually tiny light-sensitive squares. Each pixel registers the brightness of the light striking it, when you click a snapshot. These pixels in a photograph cannot be identified unless you magnify a digital image. On enlarging an image, you will find that the whole picture is a web of inter-connected lines known as rows and columns forming small boxes or squares filled with colors. These boxes are known as the pixels. Resolution is the camera’s ability to classify and effectively present discrete image information, such as details, patterns and textures within a given photographic image and it corresponds to how large a photo can become without becoming unacceptably blurry or grainy. Camera and image resolution is measured in Pixels Per Inch or PPI.

Measuring the Resolution

The resolution of a digital image

Resolution can be identified by the measurement of pixels in dimensions of height and width. For example, a camera manufacturer can describe the resolution of the camera as 3904×2598 (W x H) pixels, which again can be termed as 3904×2598=10,142,592 pixels. If this number is divided by 1 million, the figure thus attained will come out to be 10.1 megapixels (one megapixel is equivalent to one million pixels). Hence, the resolution of the image can also be described as 10.1 megapixels, or 10.1 MP.

Image Resolution Printout Guide

Image resolution printout guide

The Rule of Thumb here is – the greater the number of pixels in an image, the denser the picture information and therefore the higher the resolution. Higher resolution provides more detail within your image and allows for larger printouts with smooth, continuous tone and color accuracy.

Scanner Resolution

Scanner Ressolution

A scanner is the critical link between non-digital and digital formats. Any analog image can be turned into digital form using a scanner. The question is how sharp is that image going to be? A scanner’s resolution is measured by a pair of numbers, such as 300×300 ppi, 600×600 ppi, or 2400×4800 ppi. This represents the resolution as the scanner moves horizontally and vertically across an item (like a slide or a photo print) during the conversion to digital. The higher the ppi the more image information is captured at the pixel level, thus giving your photo more overall detail, sharpness, and color accuracy. So that when you look to use the scanned image, you have a greater ability to edit, manipulate and otherwise tweak the image. You’ll likely have to do some “clean up” when you bring an analog image to the digital work space. Greater scanning resolution also enables you to make larger prints. To scan photo prints, you need at least 300 ppi and 600 ppi is recommended for scanning line art documents at original size.

Monitor Resolution

Monitor Resolution

Computer monitors are diagonally measured in inches. Therefore, the image displayed on the computer monitor is the composition of horizontal and vertical squares known as pixels. The total number of pixels that can be displayed on the screen at a time is called the resolution of the screen. This resolution is normally described in the pair of numbers, such as 2560 x 1440. This means, the computer screen is 2560 pixels wide and 1440 pixels tall. Other popular sizes are 800 x 600 (SVGA), 1024 x 768 (XGA), 1280 x 1024 (SXGA) and 1600 x 1200 (UXGA). The actual number of pixels per inch depends on both the resolution and size of the monitor. An image with the same number of pixels varies on a monitor, depending on its size, as the same numbers of pixels are broadened over a larger screen. One pixel on a color display is actually a combination of three colors red, green, and blue. These small elements which form an image on the monitor are called pixels, thus monitor resolution is measured in Pixels Per Inch or PPI.

Printer Resolution

Printer Resolution

The printer resolution measures your printer’s ability to lay down an effective amount of color or black ink to accurately and smoothly reproduce your digital image. The resolution is measured in Dots (of ink) Per Inch or DPI. Your typical laser desktop printer has a resolution of 600 ppi, while inkjet printers can have a resolution of 2400 dpi or higher. This is why inkjets are used for photographic printing, because the high resolution easily allows for continuous-tone images with accurate reproduction of the colors, the shadow and highlight detail, and the overall image detail. Inkjet printers have 4 to 10 colors, which can be used for printing (at least CMYK and up to multiple Black inks for better, smoother, heavier Black reproduction). You shouldn’t think that you will improve the quality of your image if you use a higher dpi printer. That’s only possible if the original image file has more pixels – from being photographed at a higher resolution. If you try to enlarge an image beyond its resolution by using a high dpi printer, all you achieve is a photo with pixels that have gotten bigger, not denser. Thus the printed image looks unpleasant. So, if you want to produce sharp and good quality prints, your image must hold a large numbers of pixels close to one another.


Resolution is often misunderstood when it comes to digital photography, because each piece of equipment measures it differently and therefore the “value” isn’t cross compatible. However, it’s essential to understand how the resolution of each piece of equipment in the workflow operates so that you can obtain the best picture possible for the end-product that you’re after. Obviously a 12 megapixel camera is overkill for images that are going to be posted to social network sites on the web. And a 300 dpi printer might not be adequate if you’re looking to make Fine Art quality photo prints. Also, it’s not a “safe bet” to get as much resolution as you can afford, because you might never truly use it and therefore your dollars can be spent better elsewhere (like on a better lens, which you should NEVER skimp on).

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