What You Need to Know About PPI and DPI


If you have been thinking whether PPI and DPI is all but the same thing in stock photography, then definitely you’ve downloaded this tutorial to learn more. It’s in this piece of writing that you will realize the two are not interchangeable nor do they mean the same thing. We’ve explained the terminologies and tried to explore different aspects of each.

Introduction to PPI and DPI

It is important for you to know that there is a significant difference between DPI (Dots per Inch) and PPI (Pixels-per Inch). Nevertheless, the two continue to cause confusion and are sometimes used interchangeably. In order to get everything right; PPI refers to digital image resolution, especially how you view it on a screen. On the other hand, DPI specifically refers to how an image(s) is printed. This seems simple, but it’s an unfortunate situation how even big companies continue to use the words interchangeably while discussing a number of things.

PPI Explained

As stated, PPI is used in reference to screen resolution-and is relatively easy to understand. As a matter of fact, a pixel is a tiny, square-shaped, block-of-color. Remember, this can be a photograph or just any type of graphic. Overall, these are usually composed of thousands upon thousands of these tiny pixels. Therefore, PPI is all about the total number of pixels-per-inch in any digital image. It is vital for you to know the number of PPI in your image will affect two things; one-is the print size and second is the quality of the output. If a digital image contains a high number of pixels per inch, then definitely image is more detailed and crisper. In a nutshell, high “resolution” means a clear image.

The Relation between PPI and Print Size

In many cases, people think if just because an image looks good on screen it will retain its beauty when printed. As a matter of fact, this is not usually the case. Of course, whenever you want to print your images you aim at retaining the highest resolution-PPI- possible. The best thing for you to do is understand how large your print should be in order to retain quality and finer details. In other words, quality is dictated by the number of pixels the maximum size that you can print without affecting clarity. It’s for this reason that professionals recommend a 300PPI in every print.

Example as used in Stock photography

If you have a 3.2megapixel image saved at accepted 300PPI, and it measures 2,048 horizontal pixels, while the vertical pixels stand at 1,536, (2,048 x 1,563 = 3.2 MP). You can easily find out the maximum print size at professional 300PPI by simply dividing each dimension with what the experts recommend. In this case, you must divide the 2,048 by 300 which gives you 6.8, while 1,563 by 300 will give you 5.2. Therefore, the maximum print size of your image should be 6.8-inch horizontal and 5.2-inch vertical. If you go beyond these dimensions, the quality will be poor. Overall, based on this example photorealistic quality is only achieved when everything is followed per the professional guideline.

Stock photography-What about DPI (Dots-Per-Inch)

DPI (Dots per inch) is all about the printing of any photo on paper-and also relates to how a paper-photo is scanned. Overall, the traditional printing methods have always considered the use of patterns of dots when it comes to transferring photographic images on paper. In other words, every single pixel in any digital image is considered and when printed different colored dots are used in order for the purposes of clarity and overall quality. These particular dots are usually made by the use of different colored inks found in the printer; and these include; Yellow, magenta, black, and cyan. However, there are some photo printers that will have more than 4 colors. In all cases, printers will combine these colors to come up with specific colors of the images. If you use a magnifying glass, then you can clearly see the dots.

Important note about PPI and DPI

It is of utmost importance to know that when any kind of digital image is printed, the pixels are usually converted to dots. As stated before, pixels are close to one another and there is no space between them. On the other hand, dots vary as they have space. As for this reason, DPI is much lower than PPI. In order to get DPI, you need to divide PPI by 2. Therefore, as a rough estimate 300PPI becomes is 150DPI and this becomes the standard for printing quality images.

As a reminder, PPI is the total number of square pixels per inch of a digital image in stock photography, whilst DPI is a dots-per-inch of the printed image.

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