[Scribus] quality images for press (digital camera? cheap/freeonline stock s? scan?)

Marvin Dickens marvindickens
Thu May 5 08:29:02 CEST 2005

On Thursday 05 May 2005 01:34 am, Craig Ringer wrote:
> On Thu, 2005-05-05 at 01:19 -0400, Marvin Dickens wrote:
> > I second Leica lens quality. In the event you can't afford/get a Leica
> > lens, Nikon is my second choice.
> My work had a Nikon D1 before we got the more recent Canon EOS 10D. The
> Canon was a massive step up in quality, performance, and reliability.
> It's not as solidly built or "nice" a camera, but unlike the D1 it works
> reliably.
> It wasn't just one particular faulty D1 we got, either. Before we gave
> up on them we had three TOTAL replacements. They all just went flakey
> and died.
> I was also never particularly happy with the D1's ability to handle
> weird lighting. It was extremely prone to colour casts and incredibly
> sensitive to exposure in some lighting conditions. I had to "fix" some
> truly ghastly photos at various points, especially things like shots
> inside art galleries. Unfortunate, as it *did* produce beautifully
> sharp, clear shots when it wasn't playing funny business with the
> lighting.
> Perhaps Nikon have improved the D1 since then - we did start out with an
> early model. Hopefully they've improved the software too, since it's was
> worse than the Canon software we have (but don't use) now.
> Ah well ... it's entirely possible I was unlucky, or that the
> photographer at work is somehow intrinsically destructive to Nikon
> digitals. Still, my experience with the D1 wasn't a good one.
> > Also, as someone else pointed out, digital zoom is absolutely worthless.
> > This technology, like image scanners that claim 2400 x 2400 DPI
> > resolution (Or better), is based on digital algorithms that enhance by
> > guessing what the image should look like if enlarged - In fact, the
> > algorithm produces an enlargement that is hocked off to the user as a
> > magnification. The quality, as my high school aged nephew would state:
> > 5ucks.
> The worst thing is it's just one of the many dodgy scams in the
> business. Those resolution claims don't usually even come with a little
> (* interpolated; physical resolution 2400x1200 dpi); similarly dodgy
> scanners rarely say (* theoretical; measured dynamic range approx 3.0).
> I laugh when I see scanners claiming "Dynamic range of 4.2!". For why:
> http://www.scantips.com/basics14.html
> http://www.photo.net/learn/drange/
> It seems scanner manufacturers really must have discovered the "new
> black" and "new white" :-P

A lot of manufacturers are full of it . Specified double-numbered resolution 
like 600x1200 dpi are interpreted as follows: 

first number - resolution of optical system 
second number - resolution of stepping motor which moves scanning head.

Out of these numbers, only optical system resolution counts. Therefore, 
scanners with optical system resolutions of 600x600 dpi, 600x1200 dpi and 
600x2400 dpi are essentially the same. In essence, forget about interpolated 
resolution if you need quality. This is because stepper motor technology has 
hit the wall regarding shorter micro steps and both high and low priced 
scanners suffer from this limitation. Sometimes, its possible to scan at 1200 
dpi on a scanner with 600x1200 dpi resolution *if* the firmware is really, 
really, really excellent - Trade secret type excellence. Plus, this works, if 
and only if the scan is performed *exactly* under the physical conditions 
outlined by the manufacturer. This is optics at its best.  SOHO scanners do 
not fall into this genera.  

Now, Interpolation is the art of generating missing pixels - read guessing 
what the pixel should look like and where is should go. - So even with 
really, really good firmware, it's a hit or miss proposition. The software is 
guessing where the pixels that CCD head that is driven by stepper motor 
missed between micro steps. Regardless of what any manufacturer or sales 
person says, software with fractal interpolation capability that cost a 
couple of hundred dollars interpolates poorly. Good interpolation cost 
real money: 10K USD and up.

Never pay attention to the high-number color depth specifications. SOHO 
scanners use cheap quality CCD's, and the extra bits are really noise 
(Specifically, signal noise generated in the CCD itself and in the event the 
scanner is really cheap, from TTL lines as well). Typically, SOHO flatbeds 
with 24, 30, 36, 42 and 48 bit color depth do not differ in terms of output 
image quality. High quality scanning software has much more impact. 

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