Print size

You want to know if the resolution of your camera will be sufficient to have quality prints?

The definition of the photo limits the resolution of the print

  • Definition of a photo: it's the number of pixels that compose the photo
  • Print Resolution: This is the number of dots printed every 1 inch. It's expressed in dpi (dot per inch)

Ideally, we use at least 1 pixel of the photo to print 1 point of the print.

For example, a print in 4 x 6 in at 300 dpi requires at least a definition photo 1200 x 1800 pixels (4 × 300 = 1200 and 6 × 300 = 1800).

2 cases may occur:

  • The definition of the photo is higher than necessary: ​​no problem, a printing point will actually be the average of several pixels.
  • The definition of the photo is less than that needed: problem: either we do not change the definition and the print will be pixelated, or we increase the definition of software and the result may be mediocre enough (the software cannot invent the missing pixels).

Minimum distance of observation of a print run and choice of the resolution

If you have read the definition of the circle of confusion (Case Properties) you know that the eye has a limit to distinguish the details. It has in fact a limited angular resolution, of the order of one minute of arc (1/60 °), which corresponds to a vision of 10/10 (a detail of 0.01 in at 40 in). The smallest detail visible to the human eye is 0.002 in.

In addition, our field of vision is also limited. We fix at 40 ° field of vision max to be able to distinguish the forms.

  • l: width of the photo
  • d: minimum viewing distance "comfortable"
  • p: size of the smallest detail that can be distinguished.

dpi = p

With a lower resolution the points will be distinguishable, with a higher resolution the difference in quality will not be visible.

Attention, the choice of the minimum distance of observation is debatable; it's quite legitimate to want to look at the print closely to admire the details, the resolution to use is then a function of the distance you want to put between you and the photo.

Use

1. Choose the unit of printing

2. Choose the size of your printing

In the bottom area

You get the information for the optimal viewing distance of printing:

  • 3. The theoretical distance of observation of the printing to see all of it
  • 4. The minimum resolution for this printing
  • 5. The minimum dimension of the image of this printing
  • 6. The size of the smallest detail that can be distinguished

The following lines provide information for closer viewing distances than the optimal viewing distance.

7. You can limit the resolution to the smallest detail visible to the human eye.