What is the dpi of a photograph developed by a drugstore Does it depend on the dpi of the original photo taken by my digital camera How I can I ensure a photo is 300dpi?

Answer 1

Found on the web... Shoot on high-resolution settings If you don't want to think or learn about pixels and how they relate to resolution, then the simple rule of thumb is to always shoot pictures on the highest resolution setting your camera offers. Depending on your camera, this usually means shooting pictures in Tagged Image File Format (TIFF), JPEG LARGE, or JPEG FINE capture modes. If your camera offers RAW mode, you can shoot in RAW mode, and then save the images as TIFF when you convert them. Shooting with these modes means that little or no compression is used when storing the pictures on the memory media. Compression saves space, but it also discards bits of information from the image. Those bits of data are part of the overall image resolution. The more bits discarded during compression, the lower the resolution of the image. However, if you do want to think about resolution, then a key point is that the photo quality standards for prints range between 200 and 300 dots per inch (dpi). Commercial labs such as Fujicolor Processing prefer to use a resolution of 300 dpi when printing photos sent from MSN Photos members. To see if your camera can produce an image at 300 dpi in the size of print you want, you can do the calculations yourself. For example, you generally need between 240 and 300 pixels per inch (or in printer terms, dots per inch, dpi) at the size you're printing the image. To print an image at 300 dpi at 5" x 7", multiply 5" x 300 pixels and 7" x 300 pixels. The results are 1500 and 2100 respectively. That means that the camera should produce an image size of 1500 x 2100 pixels. (Note that the minimum and maximum resolutions can vary considerably depending on the printing resolution used or being quoted.) Next, to find out if your camera can produce images that you can have printed at 5" x 7", multiply the image width by the height in pixels: 1500 x 2100. The result is 3,150,000, or 3.15 million. The number in millions (in this case, 3.15) should be roughly equal to the megapixel rating (or number) of the camera. In short, if you want consistently high-quality, 300 dpi prints at 5" x 7", a 3-megapixel camera will provide those results. Or, if you choose to print at a lower quality setting, say 200 dpi, you can get 5" x 7" prints from a 1.4-megapixel camera. While 300 dpi is the generally accepted norm, 300 dpi is also often unrealistic for enlargements. For example, to get an 8" x 10" print at 300 dpi, you need a 2400 x 3000 resolution (or 7.2 million pixels) image, which is impossible to achieve with most current consumer-level digital cameras. As a result, many labs print enlargements at less than 300 dpi with very good results. At the photo lab At commercial labs that print poster-size photos, such as BigNose.com. For example, to create photo-quality images for poster-size enlargements, BigNose.com often interpolates (adds pixels to) the original image. In other words, the software analyzes the image and makes a best guess about where to add pixels based on nearby pixel information. This produces a higher-resolution image that can be printed at poster sizes as large as 36" x 48" with good results. If you are scanning images, Peter Burian offers this advice in Get Great Prints from Digital Images. "If you want to make excellent prints from slides, negatives, or photographs, plan to order or make high-resolution scans. Image files that are 4 megabytes (MB) in size may make a fine 4 x 6-inch print. For making an 8 x 10-inch print suitable for framing, you'll want at least a 9-MB file. For a superb, exhibition-quality print of that size, I prefer to start with a much larger file, at least 18 MB in size." Be sure to save your scanned file in TIF or JPEG format with as little compression as possible. Most commercial printing labs advise that if large file size is a problem?if, for example, you don't have space on your computer's hard drive for a large file?then it's better to save the file at a lower resolution with less compression than to save it at a higher resolution with more compression.