Every photograph, in digital form, is made up of pixels. They are the smallest unit of information that makes up a picture. Usually round or square, they are typically arranged in a 2-dimensional grid.
The number of pixels in an image is sometimes called resolution. Resolution is the amount of pixels per length unit. If we are using the term to describe pixel count, we could express resolution as the width by the height, for example a monitor resolution of 1280×1024. This means there are 1280 pixels from one side to the other, and 1024 from top to bottom.
When picture size is expressed in pixels without mentioning the resolution, the actual print size is unknown. To achieve a print size in inches, divide the size in pixels by the desired print resolution. See chart below.
240-300 resolution is ideal for print (printing quality will make a difference). Web size images are best at 72 dpi. An image may look great on your monitor, but not in print! Let’s do the conversion backwards. On the following chart, I have an image with 3200 pixels. I know that I can print around 13″ without losing quality.
I recently took Ryder to get his rockin’ 80’s hair cut and took the photo below on my iPhone. The 8 megapixel iPhone 6 snapped a high 2448 x 3264 pixel image which can print at 300 dpi as an 8.16×10.88. (note, if I print an 8×10, there will be cropping. This is called aspect ratio)
I resized and cropped the image to a 4×6 at 300 dpi and a 4×6 at 72 dpi. The pixel count changed when I changed the resolution.
As you can see, the image on the right is more “pixelated” than the left. The image on the right contains less pixels per inch (dpi or ppi), resulting in a less sharp image. (please note, once you save an image at 72 dpi, there is no going back to 300 dpi)
Relating Pixels to a Jar of Skittles
All of this digital talk can become overwhelming. In simple terms, I like to relate pixels to skittles in a clear glass jar. The jar is much more pretty when full of vibrant colored skittles. When you remove skittles, or increase the jar size, you lose the clarity and brightness. The skittles aren’t tight and full, thus they have to expand to fill empty space.
Can I Add Skittles/ Pixels?
No. If you snap a low resolution photo, take a photo from the web, or use a small instagram sized image (612×612 pixels) to print larger than capable, it is not possible to add pixels.
Luckily, when you upload and order prints at Persnickety, our online software will warn you when you have an image that is lower resolution than recommended. You can then go back and be sure you uploaded the image intended, maybe you resized for web in photoshop, or maybe this image just won’t work for the size desired. As always, we’re here to help! Email us at firstname.lastname@example.org for assistance.
Why is uploading taking forever?
Having more pixels than you really need can actually hurt image quality. Photos with too many megapixels also take much longer to upload and might even fail partway through or become truncated. Extra- large photo files will quickly fill up your storage space with unnecessary data that you probably won’t need, use or want. Resize tools are most likely available in the photo editing software you are currently using. We recommend resizing your images to the proper pixel ratios before ordering prints.