Counting the Dots and Upsizing
August 10th, 2011
The number of pixels in an image determines how far you can enlarge your digital images in print. Each pixel represents a square in an image. The more squares there are, the greater the clarity of an image when enlarged. Usually, the general accepted standard for professional printing is 300 pixels per inch (ppi). For ordinary printing, it’s 200ppi which is more than enough for ordinary use. The difference is seen when the image is enlarged to its maximum size for which a picture can be printed.
How big a pixel can be depends on how far away the print is when viewed. Working out the maximum printable size for the number of pixels for your image is simple. You can use the tools in any manipulation software such as Photoshop and Elements. The image size window will show you the printable size for the set number of pixels per inch. You can hen change the pixel concentration to make the image bigger or smaller.
There is a confusing question regarding pixels and dots. The resolution of digital images is measured in pixels which is an image file that has no physical dimension. It is only when pixels are displayed or printed where their size is visible. Pixels per inch help calculate just exactly how big an image can appear for a particular use. Printers and paper are sold based on how many dots per inch (dpi) is their capacity. Printers can also have the option to allow you to choose dpi settings you require.
Dots per inch vary from pixels per inch in a way that dpi rating is a way of describing how small a dot of ink the printer can create on paper. The more dots of ink in a printed image it has, the finer the detail in the final outcome. This is only apparent when you use paper that has the capacity to show it. If you’re using ordinary paper, it would only be a waste of ink to use higher dpi settings.
Economy
Photo – 720dpi and 1444dpi are reserved for good quality photo paper.
Photo – 2880dpi or higher is best use only for fine, glossy media.
When using basic calculations, an uncropped image shot using a 3 megapixel camera can be printed at just about 10x8 inches at 200ppi. This can have a maximum output of 7x5 ices if you use 300ppi as a standard. You can however still produce larger prints with a 5 megapixel camera by manipulating the image using an editing software. By using the program, you can add more pixels to in image so that it can be further enlarged without showing the tiny squares called pixelation.
This process increase the size of the image file as well so only do this to images that need upsizing and not storing. This process is called Interpolation. By using a software to make a guess as to how to add new pixels to older ones. Upsizing means that a image produced by a digital camera can be printed out at a far greater range of sizes than the standard norm. There can also be some quality loss, Photoshop has five Interpolation processes you can choose from. Bicubic option is for all around use. Depending on the type of image, each may produce varying results. You can choose the best tool that fits an image for better quality.
The resampling process should be done before the image is sharpened. For large changes in the number of total pixels, it is worth doing the upsizing in stages than all at once.
