A lot of printers print at less th an 300dpi, which is the standard for good
halftone reproduction, and is the digital equivalent of the old standard 150
line screen. A fuji frontier outputs at somewhere aroune 240 dpi, and the
bigger, better Durst printers also use a similar number.
There is a big difference between printing on photo paper and inkjet
printing. Even at 2800dpi, the goal is to suppress what would be a noticable
dot pattern. Different inkjet brands have different ways of dealing with
that.
Bill pearce
----- Original Message -----
From: "John Hudson" <OM4T@xxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, December 02, 2009 10:22 AM
Subject: Re: [OM] how many megapixels here?
> Pixels per inch "PPI" and Dots per Inch "DPI" are different concepts.
>
> PPI refers to the pixel resolution of an image. DPI refers to the
> resolution
> of a printer [so says Martin Evening in his Adobe Photoshop for
> Photographers book].
>
> According to the "New Epson Complete Guide to Digital Printing" book it
> states that "Epson prints at three photo settings: 720dpi, 1440 dpi and
> 2880
> dpi. Some Epson printers let you choose these numbers; others do not.
> Typically, however, the Photo option selects 720 dpi, Best Photo selects
> 1440dpi and Photo RPM gives 2880 dpi"
>
> If Epson could satisfy discriminating customers at the "300dpi" level I am
> sure that their printers would be putting out 2880 dpi
>
> Given this information I suspect that printing at much below "300 dpi" is
> going to produce a poor print.
>
> The question is the relationship between pixels and dots, along with LPI
> [lines per inch] when transforming a pixel measured image into a dots
> measured image on paper.
>
> jh
>
>
>
>
> ----- Original Message -----
> From: "Ken Norton" <ken@xxxxxxxxxxx>
> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
> Sent: Wednesday, December 02, 2009 11:51 AM
> Subject: Re: [OM] how many megapixels here?
>
>
>> >
>>> Is an 11 Mpix sensor big enough with make a 48" wide image with more
>>> than
>>> enough fine detail to withstand careful up close scrutiny ?
>>
>>
>> If the edge-sharpness is there, the answer is a resounding yes!
>>
>> All this talk about maintaining 300dpi for printing is a bunch of
>> hogwash.
>> The eye is able to discern a line at 300dpi, but is unable to see
>> anything
>> else down there.
>>
>> To prove me wrong, do the following:
>>
>> Make an image file in your editor of choice and create a pattern of 1
>> pixel
>> wide vertical black and white lines. Print this at 300dpi. Can you see
>> the
>> pattern? Let's go one step further. Add horizontal black lines. This
>> should give you 1 pixel white dots surrounded by 1 pixel of black. Can
>> you
>> see the dots?
>>
>> Now, start scaling the images up to 200dpi on the printed page. Then try
>> 150dpi. Even try 75dpi.
>>
>> At 150dpi the human eye is easily able to discern the lines and dots
>> (provided that the scaling engine didn't blur things too much), but just
>> barely. If the edges of the lines remain sharp and not blurred, the
>> detail
>> is maintained to the maximum of what the human eye is comfortably
>> viewing.
>>
>> Now comes the fun part. I hope that the three prints are identical.
>> Randomize the prints and grab one and guess which one is at which
>> resolution. Hand the 150dpi print to another anal-retentive photographer
>> and ask him/her what resolution it was printed at.
>>
>> Folks, when tests like these are performed without bias, you'll find more
>> times than not that the lower-res image looks exceptionally sharp and
>> highly
>> detailed.
>>
>> AG
>> --
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