Pixels and print resolution
The relationship between the number of pixels in a file and the print resolution will determine whether a file will support the print size that you want. The chart below will allow you to determine the pixel resolution required for various print sizes.
People tend to think of resolution as the “dpi” of a file, which is not at all an accurate description. Screen resolution is 72 dpi, whereas print resolution is usually stated as 300 dpi.
The “native” resolution of your camera is expressed as 72 dpi. This may sound like quite a low resolution, but let’s consider a Canon EOS D5 full-frame 12.8-megapixel sensor with a resolution of 4368 x 2912 pixels. At 72 dpi, this is a pretty big canvas size of 60.66 inches x 40.44 inches. However, the same image expressed at 300 dpi is only 14.56 inches by 9.71 inches (4368 px/300 dpi=14.56 inches, and 2912 px/300 dpi=9.71 inches).
Another example would be a Nikon D850 sensor that is effectively 45 megapixels with a resolution of 8256 x 5504 pixels. At 72 dpi that’s a whopping 114.67 inches x 76.44 inches. Again, that identical file expressed at 300 dpi for printing (8256 px/300 dpi=27.52 inches, and 5504 px/300 dpi=18.35 inches) seems much smaller.
Objectively, the only “true” measure of resolution is the “pixel resolution”, which is expressed as the number of pixels in the length times the pixel width of the image.
How find file resolution in pixels
You can determine the pixel resolution (or actual size) by “hovering” the cursor over the file name or by right-clicking and selecting “file info” or “properties”. Some file types may have to be opened using an image editor like PhotoShop to see the pixel dimensions. It will probably be something like “3000 x 4500 pixels”. This description can be converted to various sizes at different output resolutions (see the chart below).
Print output resolution
Photo and inkjet printing typically requires the pixel resolution to be between 150 and 360 dpi at output print size. However, the limits of the camera sensor’s “native” resolution may require some additional processing to achieve optimum print quality. We often use special software to optimize files for printing when it is necessary.
Please let us handle this step as improperly re-sizing a file might actually decrease the quality of the final print. As displayed on the chart below, if your file’s pixel resolution appears in or is lower than that specified in the “pink” column below, please check with us before ordering.