Archived posting to the Leica Users Group, 2000/04/09

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Subject: RE: [Leica] Analog vs. digital (long and barely OT)
From: Austin Franklin <austin@darkroom.com>
Date: Sun, 9 Apr 2000 09:45:18 -0400

> >You don't "need" pixels.  Pixels are "picture elements" and is an
> >electronics term, it has nothing to do with printing, per se. 
 Halftoning
> >has been used for years, long before 'pixels' were ever thought of... 
 In
> >halftoning, the dots are referred to as, well, dots.  The dot is not the 
> >same as the pixel, they are two entirely different concepts.

> I need pixels and you do too if you're gonna use a computer to
> convert your photo to a halftone.

That's true, but that wasn't what you said.  You said:

"What does it take to convert your photo made on film to the printed page?
 Its pixels. "

and people have been converting film to the printed page long before 
"pixels" existed.  That was my only point.  I was unclear that you were 
specifically referring to "use(ing) a computer to convert your photos to a 
halftone", so if I misunderstood you, I apologize, my mistake.

> I did not mix pixels and dots. You did.

Er, no.  Where did I do that?

> You are right, halftone dots have been around for quite awhile. That's
> how continuous tone images have been reproduced for a long time.

At least we agree on something!

>>> The usual resolution for average (133 to 150 line screen) magazine or
>>> brochure printing is 300 pixels per inch. Thats 300 pixels per inch at
>>> the final reproduction size.
>>
>>You are mixing about pixels and line screens (halftone term) here...and
>>they aren't related in this sense...

> Yes they are related. What I stated is a generally accepted, empirically
> proven conversion for the resolution needed for offset printing. It is
> standard in the industry. It is not absolute and there's no math to prove 
> it - only real world experience.

That depends on a LOT of things, such as the mask design, and the output 
device.  It may be 'generally accepted' by some, but that does not make 
"pixels" and "half tone dots" related.  I don't know how much you 
understand about half tone masks, but output DPI does NOT mean the output 
"image" is at that same resolution.  Halftone by nature is the dot is on, 
or the dot is off, period.  There is no in-between.  In order to give the 
illusion of gray scale, more dots in each array are either on or off...

> How many print jobs have you managed
> over the past 10 years or so? You have some experience to back up what
> you say, don't you?

Well, yes I do.  I have designed a commercial halftone system (Imagitex), 
and I designed some of the halftone screens (algorithms).  What ever one's 
'experience' is, has no bearing on whether one is right or not, it may have 
a bearing on whether someone else believes one is right.

> Anyway - it just 8 bits when you make film to make the plate. The
> resulting 256 levels of gray makes a convincing reproduction.

Completely agree.

> Then what lens will work as well? What's your experience with lens and
> digital cameras? Its still light going through glass.

My point was, you won't get a better digital image from a $2k Leitz lense 
with a CCD array, vs a $100 lense...  Also, since the CCD array has to be 
larger than the 35mm film area in order to fit the number of pixels, it 
will require a different design, that covers a larger 'film' area.

> "Physics" does not govern the minimum size of a pixel or film resolution.

Well, yes it does.  That's a fact.  If you don't understand why, I will be 
more than happy to give you the lo down on why that is.

> Our current level of technological development does. Density of sensors
> and resolution of film grows and has been growing since they were
> developed.

Our current level of technology is governed BY physics (amongst other 
things).  Diodes have physical limitations governed by physics.  You can 
only make a diode so small, and you can only package them so close 
together, and you can only make a wire so small (to connect the diodes to 
the periphery of the array), etc.  Yes, physics does govern electronics 
miniaturization.  It also is responsible for the "structure" that is used 
to record light on film.  They can only be so small...