Digital BW, The Print

I would appreciate group members' opinion re. what is the optimum 
resolution for grayscale images for a 1440 dpi inkjet output.  I have 
seen a number of different recommended values such as 240, 360 or 
480ppi which left me a bit confused. Thanks in advance,
Marc.

I find that I generally need at minimu 220ppi original image data to 
get a good b&w print... with certain images and interpolation and 
processing I can sometimes get away with much less.  300ppi seems 
unquestionably good.  The Epson printer driver then interpolates up 
to 720 so there might be something to sticking to fractions of that 
or interpolating up to 720... but in the casual experiments I've done 
using different interpolation schemes I have't seen any *real* 
improvement which makes it worth the time (do the math... you can end 
up with some huge files)... but others disagree.

mark

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "marcsien77" 
<marcsien77@y...> wrote:
> I would appreciate group members' opinion re. what is the optimum 
> resolution for grayscale images for a 1440 dpi inkjet output.  I 
have 

> seen a number of different recommended values such as 240, 360 or 
> 480ppi which left me a bit confused. Thanks in advance,
> Marc.

Do the following test:

take a sharply-focussed, highly-detailed, but *UNSHARPENED* (this is important) 
image of yours at 600 dpi (or more accurately 600 "spi": samples per inch) and print 
it at 8"x10" @ 1440dpi
then downsample it to 400 spi and print that
then downsample it to 200 spi and print that

and tell me if you see any difference. (I just did this myself, btw). Most people can 
readily see a difference with the 200 spi image, but can't see any significant 
difference between 400 and 600 (at least not at 1440 dpi output).

All things being equal, epson uses a custom stochastic dithering algorithm that is 
likely based on "something" in the neighborhood of 360dpi as its base from which to 
derive the dither. Send any more than that to the printer and the data is certainly 
DOWNSAMPLED by the printer. The test above more or less proves this. Stick with 
something in the neighborhood of 360 spi and you can't go wrong.

Michael Sullivan
author "Make Your Scanner a Great Design and Production Tool"


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "marcsien77" 
<marcsien77@y...> wrote:

> I would appreciate group members' opinion re. what is the optimum 
> resolution for grayscale images for a 1440 dpi inkjet output.  I have 
> seen a number of different recommended values such as 240, 360 or 
> 480ppi which left me a bit confused. Thanks in advance,
> Marc.

SPI?, that's a new one for me.

Jone Cone of Cone Editions has stated many times that he can see 
differences in a printed image up to 720PPI. Of course he has access 
to a drum scanner that can give him that resolution.

I remember Bill Berg also saying many times to size your images 
without resampling and let the PPI fall where it may. He sort of drew 
a line at 240PPI being the lowest desirable resolution for b&w quad 
printing.

BTW, I haven't heard of Bill Berg in a long time.
Cheers,
Andre

Hi Andre,

> SPI?, that's a new one for me.

Samples Per Inch.  Scanners resolution is in samples per inch...

Regards,

Austin