Arts and Photography tips and guide

Many people seem to get hung up on the DPI (dots per inch) or PPI (pixels per inch) setting within a digital photo as a measure of the quality of those photos. It seems as if there are some people who get hung up on rather dots per inch (DPI) has a better quality than pixels per inch (PPI). If you know of someone that is having this dilemma send them on over here so I can tell em.

DPI & PPI have absolutely nothing to do with the quality of your digital photo.

The resolution of your digital photo is its pixels (usually expressed as megapixels). The PPI of a paper print is a measure of quality (the paper print, not the digital photo) - but it does not have anything to do with the DPI/PPI setting within the photo. These are factors you can use to determine the quality of your digital photos:

The size of the digital image. (In pixels)

The quality of your digital camera. (camera's optics and sensor, scanner's sensor).

The digital format. (TIF, PNG, JPG, GIF)

The photographer. (You)

Use these four rules and you will be fine. The size of your digital photo is measured by its smallest component, the pixels. DPI which is dots per inch is the scale used in reference to printers meaning how many dots of color a printer can insert into a single inch on a piece of paper. Although these days the term pixels per inch is used.

While DPI & PPI are 2 different things DPI is often used when PPI is what is meant. PPI measures how an image is printed on a piece of paper. While at the same time software programs call PPI a measure of resolution. This is not the resolution of the digital image but it is the resolution of the printed output. Confusing I know. If the pixels of the digital photo are not changed, then the digital resolution won't change no matter the PPI/DPI setting.

Let's say a print shop/graphics designer/magazine asks for a photo at 300 dpi. Then they want to print it out at 5" x 7". They have a beautiful digital photo with 2048p x 1536p. You notice the photo is set to 72 dpi. So, following orders, you type in 300 to reset the dpi to 300. Now the image is resampled and enlarged over 4 times to 8533p x 6400p. You send it. The print shop/graphics designer/magazine rejects it stating that it's too grainy, color too blotched. Now you're upset. The sad thing is you already had the perfect photo (2048p x 1536p @ 72 dpi) which would have printed out beautifully at 5" x 7" (at 292.6 PPI). The print shop/graphics designer/magazine didn't really have full knowledge of what they wanted - You really didn't know how to change the DPI without resizing the image to give the print shop what they mistakenly think they need.

So - why DPI?

Older photo programs may use DPI to set the size of the printed output. With these programs you have to adjust the DPI to adjust the size of the printed output. This is starting to become outdated though. Most newer photo programs let you to set a size output for the image, regardless of the DPI setting.

Congratulations you have now been a peacemaker in the war between PPI & DPI.

Omar Erwin has developed a passion for digital photos and its many different avenues. This passion has driven him to write a book not just for beginners of digital cameras and digital photos, but for all who love participating in digital photography. You may get your free copy as a gift by going to http://www.omarerwin.com/gift.html

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