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How does DPI affect the quality of my results?
Warning: If this page loads slowly it is because it is demonstrating quality elements that require larger files than are normally available on the Internet.
Question: What are JPG (.jpg) or PNG (.png) file? What does that mean?
Answer: These are the graphic file types that belong to a graphic family called Bitmaps. Bitmaps have tiny dots called pixels. Color information is held in each of these pixels and then this information is passed to the computer - or printer - that has to do something with this map so that the image can be reproduced.
When you reduce the size of the dots (pixels) so that more of them are required, you get better images. 72-dpi (dots per inch) means that there aren't very many dots in the image and that they are bigger (so the image looks grainier) and 300-dpi means that there are many, smaller dots (so the image looks sharper).
A JPG is the most commonly used file type and is commonly used for printing and the web. A PNG is a transparent file type. This means that you don't see any background color around the image because it's clear. This quality makes it wonderful for digital scrapbookers. To see PNGs in action, watch our FREE Basics of Digital Scrapbooking movie tutorials! However, PNGs don't print out well, as they confuse many printers. This is why Scrap Girls gives our customers both file types when they purchase alphabets, transparencies and embellishments. We want to make sure that paper scrapbookers AND digital scrapbookers can use our files.
To learn more, view the article on printable versus digital files.
Question: How do these numbers affect results and file sizes?
Answer: Because 72-dpi graphics have fewer dots, they have less information that must be passed from computer to computer. The resulting file sizes are small. That's why 72-dpi has become the "de-facto" standard for sharing graphics over the Internet or through email.
300-dpi is considered to be an industry standard for book, magazine and professional printers because the dot size is small enough that the prints are sharp and clear. Because there is much more information stored with a 300-dpi file to ensure better results, the file size must be larger. This means that if you are downloading files that are 300-dpi from the Internet, you can expect that they may take a while to receive - particularly if you have a dial-up connection. But the wait is worth it in the long run because you'll have fabulous results when you print out the files! This is why Scrap Girls gives our customers 300-dpi files.
Question: But I'm not a professional printer. I use my printer at home. Why should this matter to me?
Answer: Today's new-generation, photo-quality printers are being made specifically so that they can reproduce photo print results that are equal to or superior to photo lab results.
For instance, in discussing one of their printers Canon states:
With the CP-300, you can produce prints that match the appearance and long-life of images produced by traditional film processes. Engineered for superior picture quality, these printers have a resolution of 300-dpi and 256 levels of color so you can create richly detailed prints from 2.0 Megapixel or greater cameras.
More and more scrapbookers are using high-quality digital cameras and will soon discover that it has become entirely feasible to not only save money printing out their own photographs, but also that the quality of the prints are superior than they have ever seen before on a home printer.
So the short answer that comes after a very long explanation is this - why wouldn't you want to have all of your scrapbooking print-outs be at the same quality as your photographs? If you use 300-dpi files whenever you scrapbook, you will get these high-quality results every time.
Question: Can't I just change the dpi setting and get the same results?
Answer: You may change the dpi setting at will, but if the original dpi information was 72-dpi or 200-dpi, raising the number to 300-dpi just splits the existing dots into smaller pieces and if the computer doesn't know what to do, it guesses. You will not get the increased color variations that can be found when a file was originally created at 300-dpi.
Remember, dpi is a means for computers to communicate file information with each other and so dpi is is really a mathematical formula. Your computer can't invent information that wasn't there originally, so it will try to guess what it should do and the results you will see will usually be disappointing. Typical outcomes include blurry contours and "pixilated" images. (Pixilated means visually seeing tiny squares on your image.)
Question: Is there anything special I should know about saving my graphic files?
Answer: Yes! Resaving JPGs over and over again will cause the quality to degredate. This is why it is important to retain your original file when you scrapbook digitally, which is usually some other type of file (such as PSD if you are using Photoshop, for instance). This type of file saves all of the original information, and not only allows you to edit your layout at will, but the quality won't lesson over multiple savings. Then, you can do "Save As" actions to generate JPGs as often as needed from this original file and the quality will be retained.
These types of (original) files are layered, however, and are very large. You will want to get into a routine of saving them every so often onto storage media, such as CDs or DVDs, so that your hard drive doesn't get cluttered up. When your hard drive gets too full, your computer's performance will get terrible. Avoid this by storing them elsewhere. (Make sure that you are using quality CDs!)
Original resolution: 180-dpi (145 pixels wide)
Results when photo size is increased to 300 pixels wide.
The resulting file is grainier than the original because the computer is just increasing the size of the dots. Notice the blurring.
Photo that was scanned into the computer at a resolution of 300-dpi (300 pixels wide). This photo is much sharper because the computer originally received color information about 300 dots. If the width and height of this image is lowered, the quality will still remain nice. However, if the picture is blown up in size too much, the dots will get larger and the photo will become grainy. This is a natural consequence of blowing up Bitmap images.
Tutorial by Rozanne Paxman, Scrap Girls CEO
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