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What are all these terms like pixels, megapixels, DPI, etc.?
We'll go through this fast and really simply...
Before you get into the complicated stuff... How do I print one of these on my home printer?:
The images we give you are in JPEG format, which is the same format most digital cameras use. If you know how to print a photo you've taken off your camera and saved to disk, you should have no problem printing the images you get from us.
Pixels:
Pixels are dots. The way your monitor, your TV, your video iPod, etc., shows anything is by turning little dots on and off, and changing their colors. The dots are packed so close together, you often can't tell the picture is made up of dots. These dots are called "picture elements" or "pixels" for short.
Megapixels:
This is a measurement of how many dots are used to make up an image. It's the image's height in dots times its width in dots. For example a picture that is 1600 dots high and 1200 dots wide is one million, nine-hundred and twenty thousand dots (or 1.92 million). Most camera manufacturers round this up to 2 megapixels. We render your drawings at up to 2100 pixels by 2100 pixels, which is essentially 4.4 megapixels.
Screen Size:
You'll see screen size measured in 2 ways. The first is in inches, which is a measurement of the distance from the top corner to the bottom corner on the opposite side. The other is in a number like "800 x 600", "1280 x 1024", etc. That number is pixels wide by pixels high and is called your resolution. Interesting to see that 1280 x 1024 (the common size for a 17 or 19 inch flat panel monitor) has fewer pixels than a 2 megapixel photo, isn't it? Once you get past 1.3 or so megapixels, the effect of more megapixels on how you view a photo on your screen becomes less and less of an issue. Where it becomes important is in DPI, which we cover next.
DPI:
DPI means "Dots Per Inch". This really only means something when printing or scanning. Trust us. We could explain why, but it's more math and we don't want your eyes to glaze over.
If you recall, we measured images in dots high by dots wide. The DPI of an image really depends on how many inches high or wide it is when you print it. Now this doesn't mean the size of the paper, but the size of the image on the paper. So if you have an image that is 3000 pixels wide and want to print it 3 inches wide, it's 1000 DPI. The very same image, printed at 10 inches wide, is 300 DPI. It's just pixels divided by inches.
My printer is 1200 DPI and my 2 megapixel photos look great:
Yes, the math doesn't add up, does it? If you're printing an 8 inch by 10 inch picture at 1200 DPI, that's 9600 x 12000 pixels, or 115 megapixels (wow!). How does a 2 megapixel photo print out at 115 megapixels? Well, unless you have bionic eyes, it's hard to discern a dot that's 1/1200th of an inch or even 1/150th of an inch. So the printer just stretches each pixel from your picture until it's around 8 pixels high by 8 pixels wide. With a good printer and good paper, it's generally going to look just fine.
The quality of the printer, the ink, and the paper matter. Remember from high school physics that all we're seeing is light being reflected off the paper and ink. Depending on the chemical composition of the paper and ink, and how the ink is sprayed onto the paper, little borders between stretched pixels become less noticeable because of the way they reflect the light. So with cheap paper and cheap ink, you might get a grainy print from a 2 megapixel photo, but the very same photo looks great when printed on higher quality equipment with higher quality paper and ink.
So what's the ideal DPI?:
That really depends on the quality of your printer, your paper, and your ink. Professional printing companies can make a pretty good quality print at 150-200 DPI while consumer grade inkjets may need 300 DPI or even higher.
For example, one of our preferred professional printers is CafePress. For most of their products (t-shirts, coffee mugs, post cards, etc.), to get a good, clear image, they recommend 200 DPI. Now, their t-shirts print the image at 10 inches by 10 inches, so the 2100 x 2100 image we give you is 210 DPI. It'll look great on the 10 x 10 inch printing space on a t-shirt.
For newer, good quality home inkjets with good photo paper, 300 DPI usually looks pretty good. So if you print out a 2100 x 2100 image you get from us on your home printer, so long as the printed image size (the size of the image, not the size of the paper) is 7 x 7 or less, it should look good.
