Calculate Digital
Photo Sizes
Converting a digital image from megapixels into a photo-quality print or viewable image is limited to the resolution of the original image. Using a standard 300 ppi (pixels per inch) resolution, different images have a maximum size according to how many megapixels are contained in the original image. To retain the full image, the aspect ratio (ratio of width to height of the image) should be retained.
Instructions
1. Photo file formats are "rasterized," or built from individual pixels. The files have dimensions of width and height given in pixels. Locate the photo file you want to calculate and write down the dimensions of width and height.
2. Print or display the maximum size. You can print or display digital photos at any size you want, but above a certain size, there is not enough information for the human eye to perceive them as smooth images and the individual pixels will start to stand out. An industry standard for resolution is 300 dpi (dots per inch). Divide the width and height of the photo image (in pixels) by 300. This is the "maximum" width and height for a good-resolution print.
3. Set the digital format on your camera for your target use. Digital cameras take images with a variety of dimensions. Common digital image aspect ratios (width-to-height ratios) are 4:3, 3:2, and 16:9. Divide through and you get 1.33, 1.5, and 1.77. Use 4:3 or 3:2 aspect ratios for typical photo enlargements. Widescreen 16:9 is used for viewing on a TV or computer monitor.
4. Adapt your digital photo to a typical photo format. Photo enlargements are based on the 35 mm camera exposure dimensions of 36 mm by 24 mm (1.5:1). This works out perfectly for the common 4-inch-by-6-inch prints, but cropping is necessary to fit standard 5-by-7-inch or 8-by-10-inch formats. Divide the long side by the short side and you get 1.4 and 1.25 for 5-by-7 and 8-by-10. Use these ratios to crop the digital photo to fit these formats exactly.
5. Calculate the maximum size and best print aspect ratio for your digital photo. For example, a 7.2 megapixel image 3,072 by 2,304 will give a good print size of 10.2 by 7.7 inches (approximately an 8-by-10 -nch photo print).
Tags: width height, maximum size, aspect ratio, aspect ratios, Calculate Digital