What is a high resolution image?
Is my image high resolution? And if not, can I make it so?
Common image files such as jpg, gif, png, tif, psd, bmp, are measured in pixels.
The resolution of a pixel-based graphic is the number of pixels within an inch: PPI (pixels per inch)
Whether the image has high enough resolution depends on the process being used. Generally, offset printers (paper printing) require a minimum of 300 ppi, screen printers (cloth printing) require 240 ppi.
In order to determine whether an image is high enough resolution, you need to know 3 things:
- Your image's pixel dimensions (e.g 850 pixels wide)
- The printed size desired (e.g. want to print a 4 inch image on paper)
- The resolution required by the process your image will go through (e.g. printing 300 minimum ppi)
ASSUMING RESOLUTION NEEDED IS 300 PPI
If your image is:
It can be printed in good quality at:
Your image may look ok on your computer screen (left image), but if it's not the proper size and resolution for your specific printing project, it may print poorly (right image).
If you have an existing image:
To determine what size your existing image can be printed while maintaining good quality, simply divide your image's pixel width by the resolution required by your printer. For example if your image is 850 pixels wide and your printer is asking for 300 ppi: Divide 850 by 300 (850 ÷ 300 = 2.83). Your image can be printed in good quality at 2.83 or smaller. Printing it larger will reduce quality.
Just because an image is very large in pixel dimension and high resolution it doesn't mean it is appropriate for printing. If you take a photo with high megapixel camera and you do something wrong while taking a photo, you are going to end up with a blurry or poor quality photo that may not print well at any size.
To create the right size image image for printing:
To create an image that will be good enough size/quality for printing (example 300 ppi), multiply the size you want your new image to print by 300 ppi. For example if you want a 6.5 print size, multiply 6.5 x 300 = 1950 pixels, You need to create an image that is no smaller than 1950 pixels wide. A good habit is to always start a little larger than you need (Keep in mind very large files are hard to work with and slow to transfer), you can always reduce to the size needed - you cannot enlarge without losing quality.
How can I increase image resolution? With software like Photoshop you can manually increase the size and/or resolution of an image, but that rarely - if ever - improves quality; you are simply adding pixels randomly thought the image. If you have a graphic that is not good enough quality for printing, try image vectorization.
Vector Graphics are not pixel-based therefore they are resolution-independent; meaning a vector file can can be printed at ANY size and not lose quality. To see if your image can be vectorized so you never have to worry about size and resolution, upload your image to my vector-conversions.com
Note: Vector graphics are drawings / illustrations, so the best candidates for vectorization are graphics, logos, drawings, and illustrations, because they can be reproduced in vector format and look exactly like the original or better. Photographs are not suited for vectorization unless you want the photograph to be changed into a drawing.