Digital BW, The Print

John & Steve,

A belated reply, but after years of discussing this on the old Epson-Inkjet 
list, Kennedy McEwan (who designs digital electronic kit) summed it up by 
advising that:-

    if the ppi is between 240 and 480 at your print size, leave it as it is. 
If it is below 240ppi, upsample to             360ppi, and if it is above 
480ppi, downsample to 360ppi.

All Epson desktops upsample in the driver (by various methods?) to 720ppi, 
old wideformats to 360ppi, and newer wideformats to 360 or 720ppi.

Although ppi that are not integers of 720 give rise to aliasing patterns 
with images of repeating patterns, with normal images this is unlikely to be 
seen. Upsampling to 720ppi as QImage does can also apparently have some 
undesirable side-effects, but they are also not normally seen. Upsampling to 
720ppi in QImage gives you the option of using better upsampling algorithms 
than those that are used in the Epson driver, but of course 720ppi images 
get rather large!

There is no magic at all in the widely-used 300ppi; it will lead to aliasing 
with patterns, and apparently arose simply because it is 2x a 150lpi 
line-screen.

Tests have shown that people can see improvements in resolution up to about 
600ppi (if you have that genuine resolution), and some recent printers can 
resolve lines at about the same resolution.

Bob Frost.


----- Original Message ----- 
From: "john dean" <deanwork2003@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Tuesday, August 23, 2005 3:49 PM
Subject: Re: [Digital BW] Up-rez and print at 360 or print at 300?



Yea, I would rather send the file over there at 300 or even 240 than
have to resort to upsampling. Through the years I have been amazed at
how efficient the Epson driver is at functioning at less than perfect
file sizes. But, of course this is image and scan dependent. You can
get away with more from a drum scan than a 20D file or a nikon scan
for instance - or from a scan of a bunch of trees than a subtle tonal
gradation.

John


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Moody"
<moodymz3@y...> wrote:
> I believe it depends on the difference between ones ability to
up-rez and
> sharpen, vs. what algorithms have been put into the driver, RIP, etc..
> Certainly between 300 and 360 we would be talking about pretty subtle
> differences that require a demanding eye, and side-by-side review.
>
> Best regards,
> John Moody
>
> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of
Steve Kale
> Sent: Tuesday, August 23, 2005 9:41 AM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Up-rez and print at 360 or print at 300?
>
> Given all the Genuine Fractals etc discussion I was wondering what
people's
> thoughts were on
> this.  Is it best to lower the dpi and gain size (say 360 down to
300) or
> interpolate up
> (through whatever method) and maintain the dpi?
>
> Cheers
>
> Steve
>
>
>
>
>
> [Non-text portions of this message have been removed]






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