I get asked to explain high resolution a lot so I thought I'd share my explanation here:
High resolution means an image of high quality with a lot of image detail. On a computer, image data is measured in pixels. In general, print resolution is 300 ppi (pixels per inch) and screen resolution is 72 ppi. For more detail on image resolution, read this Wikipedia entry.
How do I tell if a photo is high resolution?
- Most photos downloaded off the internet are not high resolution
- In general, photos below 300 Kb in file size or less than 1000 pixels in width or height are not high resolution
- Look at the file size/file dimensions and divide each value by 300 to get the actual printed size in 300 ppi/print resolution.
- Example 1: 640 x 480 pixels = 2.13 inches x 1.6 inches at 300 ppi which is pretty small. Example 2: 2048 x 1536 pixels = 6.8 inches x 5.12 inches at 300 ppi, suitable for most print needs.
Taking high resolution photos
If you have a digital camera and will be taking photos that might be used for a brochure or other print piece, be sure you set your camera to the largest image size (often shown in options of small, medium, large, extra large) and image quality to fine. Order extra memory cards if you need more file space.
If you're curious exactly how many pixels wide and high your 8 megapixel (or other megapixel) photo will be, check out this Digital Camera Megapixel Translator.