PPI vs DPI: A Guide to Digital and Print

A pixel is nothing but a little tiny dot.

Before understanding the meaning for PPI or DPI it is relevant to know what a pixel actually is. The term 'pixel' comes from the terms 'picture' and 'element,' which are the smallest measurements in the digital image. The more pixels you have the higher the resolution will be, while a low number of pixels will mean a lower image quality.

Worth to note also that the number of pixels in the grid defines the resolution of your screen. Pixels are normally placed in a 2-dimensional grid. So, when someone says that an image is 320 x 50 pixels it simply means that horizontally you can count 320 pixels and vertically there will be 50 pixels. A total of 16000 pixels!

A pixel is a photographic concept with a context, Frederic. C. Billingsley, an American engineer in 1965, came up with the pixel philosophy by being the first to print an image feature in two journals.

DPI vs PPI are both words for representing the size of images. While identical, they are not the same thing:

  • DPI is Dots Per Inch, which reflects the real dot of ink to be printed on paper for that image. Therefore it is a concept for printing solutions.
  • PPI is Pixels Per Inch, which defines the number of pixels on the display screen. It is a concept for digital display solutions.

Understanding any information of how an image is used or how it is etched will make a massive difference when it comes to using digital or printing goods. Therefore, when it comes to logos, it is quite important to understand where you are going to use your logo files: For that, don't forget to check our article on where you should use your logo design.

PPI (Pixels Per Inch)

Difference between PPI vs DPI

Difference between PPI vs DPI

Let's begin by understanding what PPI means. PPI is the sum of pixels per inch for digital images. The quality of the output and print size of your image will be strongly affected by this. When there are fewer pixels per inch, the pixels will be bigger, and you will get a very "pixelated" image, affecting the output quality. It seems rudimentary, but for many, the real confusion of PPI vs DPI starts here:

For an acceptable PPI for a print out of your image, there are a few different kinds of numbers put around. A lot depends on the fact that the size of the print is small or big.

You get away with a lower PPI, having the image look okay; this is because you look at a giant print from a far distance than a small print. The PPI affects the print size of your image.

There are ways you can change the print size of the image by resampling or by not resampling. Resampling will change the size of the print, and this usually is not supposed to be done, nor it is advised.

So just in case you don’t resample, changing the PPI settings will increase or decrease the print size: it will increase if you will drop the PPI and it will decrease if you improve the PPI.

Resampling a Logo

Picture 2 - Resampling a Logo

Pixels do not exist on paper, but to simplify the explanation of PPI and print size, I want you to imagine that each image pixel from a digital file to be represented by a small square on the photo paper.

Resampling is not suggested: when you resample and change the PPI, you will lose pixels (when you set it to low PPI), or you will have pixels created (if you boost the PPI).

Creating pixels is an awful idea, computer-created pixels are not good, and the output is not satisfying, so it is not suggested. Throwing away pixels is fine as long as you don’t need a bigger size of the image that is why saving the original file is a good idea.

DPI (Dots Per Inch)

72 DPI vs 300 DPI

Picture 3 - 72 DPI vs 300 DPI

Picture 3 - 72 DPI vs 300 DPI

So now let’s understand what DPI is and what DPI stands for and what role does it play:

  • DPI is technically dots per inch. Like tiny little dots of ink, not square picture elements.
  • DPI is referred to printers too. Nowadays printers use more colours for every pixel output as it is made up of different coloured inks, but earlier they used only 4–5 colours.

You are making up to the colours for the image that the printer needs to be able to mix the inks, so a little number of colours is recommended. It's also relevant to understand what Sub-Pixels are:

  • Every pixel of your picture is made up of a series of small tiny dots. Generally, the more you raise the DPI, the better is the tone colour of the image, the colours should look nice and combine between two colours for smoothness.

When you use too much ink, the print job will be slow. You should be changing your printers setting to a lower DPI to save the ink and make the print job faster; you will recognise a difference in the quality of course.

Printers create a "print" by spraying little droplets of ink on the paper. It takes many dots to form one pixel for the image. The layout of the ink droplets is all taken care of by the internal software of your printer.

Tiling pixels directly on top of one another is a big NO for recreating your image and printers don’t do that. Instead, it is better to recreate your image by sputtering out minute dots consisting of a blend of different colours Cyan, Magenta, Yellow and Key (black), which in-cooperate to generate hues by the decreasing colour model. In the end, DPI measures the density of the space between the dots.

Resolution

Image Resolution

Picture 4 - Image Resolution

The unit resolution reflects dimensions of width x height and is the pixel attribute and can be used for any image on a digital medium or in print form. Higher DPI means high resolution and no resolution does not indicate the size. They are different terms altogether. There is always a tiff about more the resolution, images are to be bigger, but that is not the case. 300 dpi is the standard resolution.
They're different words. More resolution is often a slight argument, pictures are larger, but that is not necessarily the case. The regular resolution consists of 300 dpi.

All this matters to the customer because, as a thumb rule, the higher the resolution, the better the tone and the smoother the colour blending.
150dpi is almost considered to be the minimum requirement for outstanding photographic recreation in books and magazines. The newspaper typically uses 85dpi and the effect is obvious; individual dots are noticeable and some information is lost. You can never guess that billboards are as low as 45dpi when you're looking at it from a distance.

The difference between DPI vs PPI

PPI vs DPI

Picture 5 - PPI vs DPI

The main distinction between DPI and PPI is that the DPI is a physical ink-dot to be printed on paper, while the PPI is the number of square pixels in one inch of the image shown on a computer display. DPI reflects the characteristics of a physical printer, and PPI is the characteristics of a digital image.

In short, these words reflect the frequency of dots and pixels contained in one inch but on separate devices. If your file reaches 300 PPI, this will affect the printing of your picture, and that is what you need to take care of.

Conclusion

Make your pictures smaller, it will be the best thing you can do. Think about how your image is going to come out and make it only as much as big or small it is required. Analyzing the appropriate DPI vs PPI to be used for your image, picking up a suitable size in pixels is extremely important.

There is different software available for making changes from DPI to PPI or PPI to DPI if you need any help feel free to contact us.

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