How many PPI (pixel per inch) is needed to make it so that human eye can't detect...

[Airness23]

How many PPI (pixels per inch) is needed to make it so that human eye can't detect any more detail? I've heard 300? or is it 200 thats sufficient? There has to be a limit to how many pixels one will want to fit in an inch since human eye wont be able to detect a difference.

And on the side note, would that 300ppi match film quality or is it 200ppi or what is the right number? Thanks.

The reason Im interested in this question is to see if there will always be a need for more megapixels, knowing that the largest prints printed by professionals seem to be around 40' inches, I want to know how many megapixels will ultimately be enough to print that at "sufficient enough for human eye to not be able to detect any more detail" quality. If it is 300ppi, then that is surely a lot of more megapixels that is needed (since 8mp right now result in fine 11x8' prints) If, however, 200ppi or 250ppi is considered sufficient, then perhaps one doesn't need that many more megapixels? Thanks.

 

[john pringle]

Print size matters.

There are scientist who creep in here once in a while. I am sure a few links might lead you to them...

This cat at this link (Norman) seems to be a cool cat, Take time to email him, he will answer your query

http://www.normankoren.com/Tutorials/MTF7.html

 

[Richard Wait]

My local lab prints at 400ppi on a Agfa d.lab2, so I presume that is an 'optimum' resolution for printing photographs of a normal size.

Now, that doens't mean 200ppi or 300ppi will be unusable or different to the 400ppi to Joe in the street....

I think its pretty much agreed that the current dSLRs can't produce the resolution needed for v.large landscape photographs, if they could then MF backs woundn't be selling!

Then there is the viewing distance to the photograph! You wound't sit down and study a 40" print, that would be hung on the wall and viewed from a couple of feet, so you wound't need 300+ ppi

So, yes and no!

How many PPI (pixels per inch) is needed to make it so that human
eye can't detect any more detail? I've heard 300? or is it 200
thats sufficient? There has to be a limit to how many pixels one
will want to fit in an inch since human eye wont be able to detect
a difference.

And on the side note, would that 300ppi match film quality or is it
200ppi or what is the right number? Thanks.

The reason Im interested in this question is to see if there will
always be a need for more megapixels, knowing that the largest
prints printed by professionals seem to be around 40' inches, I
want to know how many megapixels will ultimately be enough to print
that at "sufficient enough for human eye to not be able to detect
any more detail" quality. If it is 300ppi, then that is surely a
lot of more megapixels that is needed (since 8mp right now result
in fine 11x8' prints) If, however, 200ppi or 250ppi is considered
sufficient, then perhaps one doesn't need that many more
megapixels? Thanks.

--
Regards - Richard



(This is the voice of the Mysterons, we know that you can hear us Earthmen)

 

[centralcoastmagazine]

http://www.tildefrugal.net/photo/dpi.html

Here ya go.......

 

[centralcoastmagazine]

http://www.luminous-landscape.com/tutorials/sharpness.shtml

Quote from Luminous-Landscape: LP/mm >

You may have read that some very high resolution B&W films can reach over 150 lp/mm. That's amazing. Some really terrific lenses can actually resolve somewhat over 100 lp/mm. Wow.

But are you also aware that even the very best colour printing papers can reproduce little better than 75 lp/mm? Humm. Are you also aware that the human eye isn't able to resolve any more than between 5—10 lp/mm under the most optimum conditions? > > > > > > >

Read the link above for the rest....... good reading

 

[centralcoastmagazine]

Im interested in this question is to see if there will

always be a need for more megapixels, knowing that the largest
prints printed by professionals seem to be around 40' inches, I
want to know how many megapixels will ultimately be enough to print
that at "sufficient enough for human eye to not be able to detect
any more detail" quality.

http://www.vividlight.com/articles/3116.htm

Here is the answer to that question but they only go up to 13x9 print size,
but modern high MP cameras can make a native 40 inch print. This would
be a scanning back like available at Betterlight.com You can upsize in
PS, but there are catches.

Beware of Imposters

There is true resolution and interpolation. Interpolation is the process of "sizing up" a digital image by adding pixels that were not there originally. Since every pixel must have a color, this process usually involves assigning an intermediate color to the "invented" pixels based upon the colors of the pre-existing pixels surrounding the new ones. The result is a larger image in terms of resolution, but one that now has less clarity because you simply cannot produce something from nothing. Interpolation is most common on low dollar, entry-level digital cameras. Just keep in mind the lower the real resolution the fuzzier the interpolated image will be.

 

[Michael Long]

And on the side note, would that 300ppi match film quality or is it
200ppi or what is the right number? Thanks.

300 ppi is what commercial press people usually say they want.

240 ppi is a good number for inkjet.

But a lightjet can do wonders with 200 ppi.

 

[AlanF]

How many PPI (pixels per inch) is needed to make it so that human
eye can't detect any more detail? I've heard 300? or is it 200
thats sufficient? There has to be a limit to how many pixels one
will want to fit in an inch since human eye wont be able to detect
a difference.

The eye has a limit of angular resolution of 2 arc minutes for resolving a line pair.

The angula resolution depends on the viewing distance.

The 300 PPI viewed from 10 inches is just about at this limit.

I derived the following formula:

Viewing Distance = 3500 / DPI

beyond that distance your eye can't resolve line pairs at that DPI.

See http://forums.dpreview.com/forums/read.asp?forum=1033&message=6394366 for details and references.

 

[AlanF]

Also see http://forums.dpreview.com/forums/read.asp?forum=1014&message=6507954

 

[hank]

this is getting near the threshold, but a well sharpened image right near the threshold will pop nicely on the page.

a 3 mp image can go to 8.6 inches wide natively
a 6 mp image can go to 12 inches wide natively
a 8 mp image can go to 14 inches wide natively
a 11 mp image can go to 16 inches wide natively

again, this would be for 133 magazines, not prints

the theoretical lower limit would be 239.4 ppi for 133 line screen i believe.

 

[Airness23]

Thanks a lot for all your answers, 250-300 ppi seems to be the limit when viewing from 10 inches is my conclusion then.

 

[Giclee1]

And on the side note, would that 300ppi match film quality or is it
200ppi or what is the right number? Thanks.

300 ppi is what commercial press people usually say they want.

Press people usually go for double the screen value... 200LPI print job would be best at 400dpi Now defunct due to quality software in the RIPs now.

240 ppi is a good number for inkjet.

Depends on which one... Epsons for example shine at any variable of 180 (360, 720, etc)

But a lightjet can do wonders with 200 ppi.

Amen!

 

[BobTrips]

How many PPI (pixels per inch) is needed to make it so that human
eye can't detect any more detail?

Depends to some extent on 'which human'.

All eyes are not created the same. You are most likely to find data for the 'average adult' eye. But remember that averages are a central measurement of a distribution. There will be some adults who demonstrate more acuity than 'average'.

Additionally I believe that younger members of the species can detect resolution differences up to about 400 DPI. After the age of ten acuity begin to decrease.

(For some of us old farts it could be quite low....)

--
bob
Latest offering - 'Dusk on the Buriganga'
http://www.pbase.com/bobtrips
Shots from a bunch of places (esp. SEA and Nepal).
Pictures for friends, not necessarily my best.

http://www.trekearth.com/members/BobTrips/photos/
My better 'attempts'.