IMAGE DIMENSIONS
Every digital image has measurable dimensions independent of the file size. The file size of an image denotes how much space on the harddrive the image file occupies. The dimensions of an image tell how large the image will be when viewed. Image dimensions are measured in pixels for digital images instead of inches. There are different steps to checking an image’s dimensions depending on the operating system of the computer.
MAC
- Click the image file to highlight the file
- Press command+i on the keyboard to Get Info
- Under More Info locate Dimensions.
- The numbers next to dimensions are the pixel dimensions of the image
WINDOWS
- Right-click on the digital file
- Choose Properties in the dropdown
- Click on the Details tab
- Locate Dimensions, it is under the Image heading.
- The numbers next to Dimensions are the pixel dimensions of the image
RESOLUTION
The resolution of an image describes how tightly grouped the pixels/dots that form the image are. Resolution is expressed in either ppi (pixels per inch) or dpi (dots per inch). Although it is most accurate to describe digital images in ppi, resolution is typically expressed in dpi. The higher the number for the resolution the more crisp the image will appear. If the image is only ever going to be viewed on a screen or website a resolution of 72 dpi or 96 dpi is good as it will allow the image to load quickly for anyone who needs to view it. When printing an image a higher resolution is needed. There are limitations to how high a dpi a printer can print. For true to life images we recommend a dpi of 300 and we are not able to print above that. Images with a dpi of 180 will print well and images at 125 dpi will print acceptably. We do not recommend a resolution lower than 125 dpi for printing. There are different steps to checking an image’s resolution depending on the operating system of the computer.
MAC
- Open the image in Preview
- Select Tools from the Markup Toolbar
- Select Adjust Size
- A popup should appear labeled Image Dimensions
- Locate Resolution
- The number in the box is the current resolution of the image.
WINDOWS
- Right-click on the digital file
- Choose Properties in the dropdown
- Click on the Details tab
- Locate Horizontal Resolution and Vertical Resolution under the Image heading
- The numbers next to Horizontal Resolution and Vertical Resolution are the resolution of the image and should match each other.
PRINT SIZE
When printing a digital image the image’s dimensions and resolution are used to determine the maximum print size the image can support. If an image has a large pixel dimension but a low resolution it may print well as a 3.5x5 but would probably not be suitable for a 16x20 print. The best way to reference the maximum possible print size is to compare the image’s dimensions and resolution to this pixel chart which is available as a downloadable PDF at the bottom of this page.
ASPECT RATIO
If the image is not fitting into the chosen print size then the aspect ratio of the image may not match the print size. Aspect ratio describes the shape of a rectangle in mathematical terms. The most common aspect ratio for digital images is 2:3. Ratio is expressed in the form x:x such as 3:4 or 2:3 and is spoken as a ratio of three to four or a ratio of two to three. The aspect ratio assumes the image has been divided into equal sized squares. If the ratio is 2:3 that means the image would be two squares high by three squares long.
If you are not sure of the aspect ratio of your image you can divide the long side by the short side to get the ratio expressed as a number; for an image with a ratio of 2:3 that number would be 1.5. You can then use this chart to reference the print sizes available that match your image’s aspect ratio. The chart is also available as a PDF at the bottom of the page.
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