Digital BW, The Print

Austin,

Surely not. If I take an image of 10 black and white lines of pixels (to
keep on-list) and interpolate one new line by Nearest Neighbour in PS, it is
either black or white, not gray. I only get grey lines interpolated (along
with existing black & white lines being altered to grays) using Bilinear or
Bicubic in PS. That is why I used the words 'duplicate' or 'copy' originally

Bob Frost


----- Original Message -----
From: "Austin Franklin" <darkroom@...>

> Hi Bob,
>
> > Surely Nearest Neighbour
> > interpolation just duplicates pixels (or should I say
> > quadruplicates?).
>
> Nearest neighbor takes the nearest neighbors, adds them up, then divides
by

> the number, and basically gives an average.  It certainly isn't an optimal
> interpolation algorithm, and in fact, is the most basic interpolation
> algorithm I can think of.

Bob,

Can you send me a file, both before and after, and let me see this for my
self?  That is not what "nearest neighbor" is supposed to do.

I have used pixel replication to upsize video displays (take a 640x480
output and put it on an 800x600 display, where you replicate every nth
pixel/line), and it is simply called "pixel replication".

Austin

> Austin,
>
> Surely not. If I take an image of 10 black and white lines of pixels (to
> keep on-list) and interpolate one new line by Nearest Neighbour
> in PS, it is
> either black or white, not gray. I only get grey lines interpolated (along
> with existing black & white lines being altered to grays) using
> Bilinear or
> Bicubic in PS. That is why I used the words 'duplicate' or 'copy'
> originally
>
> Bob Frost
>
>
> ----- Original Message -----
> From: "Austin Franklin" <darkroom@...>
>
> > Hi Bob,
> >
> > > Surely Nearest Neighbour
> > > interpolation just duplicates pixels (or should I say
> > > quadruplicates?).
> >
> > Nearest neighbor takes the nearest neighbors, adds them up, then divides
> by
> > the number, and basically gives an average.  It certainly isn't
> an optimal
> > interpolation algorithm, and in fact, is the most basic interpolation
> > algorithm I can think of.

> Surely not. If I take an image of 10 black and white lines of pixels (to
> keep on-list) and interpolate one new line by Nearest Neighbour
> in PS, it is
> either black or white, not gray.

Bob,

You may very well be right.  Some of information I'm finding agrees with you
and basically says that nearest neighbor "doesn't generate any new data",
and as such, it would mean it simply replicates the value of some already
existing value.  That would be the new value would be equal to what ever
original value that new point was nearest.

Averaging, as I suggested, is really a linear interpolation, using only the
nearest neighbor values, to calculate the intermediate values.

According to Cone, their driver does add intermediate values to the 8 bit
data that it gets sent, therefore suggesting some kind of linear
interpolation, and that they also expand the number of bits...since they
claim to print "thousands" of tones.

To think in terms of 8 bit files, I'm not sure using anything more than
nearest neighbor would give you much, if any, benefit, if the driver still
only understands 256 tones...since there mostly wouldn't be any new data
values added between existing values.  For color, I could see it being a
benefit, but given a non-Cone 8 bit workflow, I'd believe there would be
miniscule, if any, benefit.

Austin

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Bob Frost" 
<bobfrost@b...> wrote:
> Austin,
> 
> Surely not. If I take an image of 10 black and white lines of 
pixels (to
> keep on-list) and interpolate one new line by Nearest Neighbour in 
PS, it is
> either black or white, not gray. I only get grey lines interpolated 
(along
> with existing black & white lines being altered to grays) using 
Bilinear or
> Bicubic in PS. That is why I used the words 'duplicate' or 'copy' 
originally

If you're just copying then it's not interpolation.  
Interpolation means to take 2 or more values and arrive 
at some new value between them.  The "between" is important,
else it would be extrapolation.