dpi importance in pictures before online selling

hi everyone, amateur photographer trying to go pro: what is the importance of the dpi or ppi of a picture if i have a high resolution.

I would like to sell pictures on my website,as stock pictures or prints. I need to understand the ppi.

5184x3456 pixels with 72dpi. The resolution is high and the print is goo. why dpi is important still ?

I guess in this case, the low dpi is related to the camera (my first Canon 1300D).

sony alpha gives 35dpi now with 6000x4000 pixels..

thank you

Pixels don't have any fixed size. They can be printed or displayed as big or small as is needed. Otherwise no available digital camera image could be printed to billboard size.

Most stock libraries prefer, or demand a minimum pixel count, which has almost nothing to do with any display or printing ppi.

FWIW, dpi (dots per inch - only applicable to inkjet, laserjet or half-tone printers) isn't the same as pixels-per-inch (ppi). It takes at least four such colour printer dots to represent a single pixel.

For digital use (websites etc.) you can completely disregard dpi/ppi. They have no meaning. Instead you just need to look at the screen resolution/dimensions at which your photos will be displayed (shop, purchaser) on-screen and adjust your photo dimensions accordingly. The current 'High Definition Resolution norm' is 1920 by 1080 pixels. As screens gradually increase in resolution you may need to increase your photo dimensions to display the best 'High Definition' Resolution.

Printing pictures is a whole other territory. The standard photo-printing resolution is 300 dpi. A High-Resolution print (magazines, etc.) may even be 600 dpi. So if you know the size of the print and the print-resolution, you can work out how many pixels you need to deliver in order to make a print at that resolution quality. If you send me a PM with your email address, I can send you an Excel worksheet which you can use as a template.

Mike

PPI is just a useless tag. It is what you will use only if you are making a print.

A 5184x3456 pixels image printed at 200 pixels per inch would equal a

5184 pixels/200 pixels per inch = 25.92 inches by 3456 pixels/200 pixels per inch = 17.28 inches

a 25.92 inch by 17.28 inch print.

A 5184x3456 pixels image printed at 300 ppi would equal a

5184/300 ppi x 3456/300ppi = 17.28 x 11.52 inch print

You can advertise the image as 5184x3456 pixels with 72dpi. It doesn't matter. If the person wanted to make a 17 x 11.5 inch print he would just print it at 300 ppi. or what ever ppi he chose to make a given size print.

The correct terminology is ppi not dpi. You are dealing with pixels not dots. Since a small pixel looks like a dot ignorant people started to call it a dot. If you are talking about how many dots per inch a printer spits out then that is it dots per inch.

You can advertise the image as 5184x3456 pixels with 72dpi. It doesn't matter. If the person wanted to make a 17 x 11.5 inch print he would just print it at 300 ppi. or what ever ppi he chose to make a given size print.

 

The correct terminology is ppi not dpi. You are dealing with pixels not dots. Since a small pixel looks like a dot ignorant people started to call it a dot. If you are talking about how many dots per inch a printer spits out then that is it dots per inch.

Thank you James for the detailed answer. So the important information that I need to share is "for 5184x3456 pixels at 300ppi, the print dimensions are 17.28 x 11.52 in." ?

even if I see 72ppi on the JPEG picture, tI just need to make some calculation to show the OPTIMAL print dimensions per ppi?

"'even if I see 72ppi on the JPEG picture, tI just need to make some calculation to show the OPTIMAL print dimensions per ppi?"

Right. The "72ppi" means nothing.