sandyWhite

Hello all. Can anyone tell me what image size I need to have to equal at least 300 DPI. I’m shooting a Nikon 5500. Thanks for any thoughts.

JamesCurran Loc: Trenton ,NJ

What size do you want it printed at?

For an 8 1/2" by 11" print: 8.5*300 x 11*300 = 2550 x 3300 (about 8.5 megapixel)

For an 11" x 14" print: 11*300 x 14*300 = 3300 x 4200 (about 14 megapixel)

MT Shooter Loc: Montana

Sensor MP does not in any way translate to printer DPI. You have a 24MP sensor and if your image was properly exposed in good light, and properly focused with a decent quality lens, your images can be easily printed at 28 x 42 inches by ANY competent print shop.

TriX Loc: Raleigh, NC

DPI is a printing term, and as MT said, does not directly map to MPixels of sensor/camera resolution.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

This should provide the information that you need.

https://photographylife.com/dpi-vs-ppi

http://www.photokaboom.com/photography/learn/printing/resolution/1_which_resolution_print_size_viewing_distance.htm

CaptainPhoto

Thanks so much for the great links. They answered my questions to a "T". Really like the article with the calculators.

burkphoto Loc: High Point, NC

Digital Image *files* do not have dpi. They are simply arrays of pixels. A pixel is a number, not a dot. A dot has physical dimensions. A pixel has just an RGB value that can be translated into any size dot.

When we are planning to print, we need to refer to ORIGINAL PIXELS, FROM THE CAMERA, WITHOUT INTERPOLATION. How many of them do we need to spread over each inch of printed output? Usually, 240 PPI (Pixels Per Inch) input to the printer driver is enough to produce photographic quality at "extinction resolution", the point where we can't see the individual pixels in an 8x10 print at 13 inches, provided the printer used enough DOTS to display each pixel. You need MORE pixels per inch for smaller prints, and FEWER pixels per inch for larger prints. (No, I did not mis-state that!)

That said, there is an EXIF table attached to most digital images. The EXIF table contains a "resolution header" DPI field. This field is used to tell any GRAPHIC ARTS PAGE LAYOUT application that opens the file how big to size the pixels. Common defaults are 72, 180, 240, and 300. For instance, a 2400x3000 pixel image with a 300 DPI resolution header will open as an 8"x10" image. Change the header to 150 DPI and the same exact file will open as a 16"x20" image. Change the resolution header to 72 DPI and the same exact file will open with dimensions of 33.33" by 41.67".

This is a convention used primarily by the graphic arts industry (people who print magazines, books, newspapers, etc). The folks who grew up with early digital scanners SCANNED dots. A scanner usually divides each dimension of a photo or artwork into a grid of square pixels. If you scan an 8.000" by 10.000 inch print at 300 dpi at 100%, you get 2400x3000 pixels in the resulting file. If you scan the same print at 300 dpi and 200%, you get 4800x6000 pixels (i.e.; a 16"x20" image at 300 PPI). The scanner driver sets the resolution header of the resulting file to 300 dpi, because the operator told it to use that resolution.

Unfortunately, digital cameras have no standard for stuffing the resolution header field with a value. Some cameras default to 72dpi, the universal dpi header default for JPEG images. Others will stuff it with 180, 240, or 300. Still others let you set that in the camera menus.

[b]This drives graphic arts printers bonkers! It drives photographers bonkers, too, because they may have a high resolution file, say 4000x6000 pixels, and KNOW that will make a great 20"x30" print, but because the resolution header generated by their camera says, "72 dpi", their local newspaper printer or book publisher freaks out and tells them to submit a "high resolution" 300 dpi file.

Innocent ignorance abounds...

Fortunately, Photoshop and most other post-processing software lets you modify the files you save to change that dpi header! Just be sure when you do it that you don't throw away too many pixels.

If your editor or publisher says, "Give us a 5x7-inch photo at 300 dpi," what they mean is, "Give me 1500x2100 pixels in a file that has the dpi header set to 300 dpi!" But when you send 4000x6000 pixels in an original 24 MP file to a PHOTO LAB, they don't care what the resolution header says, AT ALL, because their software automatically re-sizes the image to 5x7 at whatever PPI they need for their printers. However, if you send 400x600 pixels, they'll probably ask for a high resolution file! 400x600 makes a nice mini-wallet print... nothing larger.

In the photo lab, dpi is an OUTPUT factor. In the lab, I might use a mini-lab with 600 dpi OUTPUT resolution, or an inkjet printer with 1440x2880 OUTPUT resolution. But I'd feed both of them 240 to 300 PPI INPUT from the original file.

TriX Loc: Raleigh, NC

👍👍 An excellent primer on the subject - this should probably be a sticky in the printer forum.

sandyWhite

A big help. Thanks

sandyWhite

Thank you a big help.

sandyWhite

Thanks a really big help

burkphoto Loc: High Point, NC

Thanks, guys!

(Off Topic)

I “grew up” in three yearbook and school portrait companies, so I had to work both sides of an actual copperhead snake infested border between CMYK offset printing and RGB photo printing. It was quite interesting, getting both sides to calm down, LISTEN, and understand each other!

I was often the translator...