Re: Large print - quality issue

[Jan Faul <jan@xxxxxxxxxxx>]

I think I’d rather be shooting pictures.

On Aug 24, 2014, at 2:06 PM, Randy Little <randyslittle@xxxxxxxxx> wrote:

This is the super techy explanation of scaling algorithms and filtering.    

http://www.imagemagick.org/Usage/filter/#filter

The 3 most common scaling filters are Mitchel, Lancoz and Sin-c (sinc)   You can google those for much less techy explanations vs that page.  

Randy S. Little
http://www.rslittle.com/

http://www.imdb.com/name/nm2325729/

On Sun, Aug 24, 2014 at 4:04 AM, karl shah-jenner <shahjen@xxxxxxxxxxxx> wrote:

Chris

A compressed Tiff or Img file of 1000x1000 plane white is only about 4 bytes
because one byte gives the colour and the other bytes give the run or number
of repetitions. Fax uses this Hoffman coding. It is lossless. You could zip
an uncompressed TIFF image file with the same effect.

Its all mathematics.

true.  And I had another look at TIF- it's been ages since I used TIF when in days of yore it was fervently defended as 'lossless' and did not compress - I was going to add that TIF was now a compressed format as the standards (as decided by the group that determines such things) had changed - but I was lazy and didn't bother

So I just saved that white 6k x 6k image again in the four different TIF compression options available to me (and yes, they are all TIF compression options)    .. the compressions options and sizes were:
compression        size
none                    105,516 Kb (interesting, - a different size from the first time)
LZW                    106,337 Kb
JPEG                    1,225 Kb
ZIP                        300Kb

With a lens there is a fundamental limit due to diffraction quite apart from
the figure of the lens. A fast lens will have higher resolution than a small
aperture. There is a lovely function sin(x)/x that gives a curve with a peak
with ripples around it and all lenses has it, with bigger lenses this curve
gets tighter.

of course - I wasn't going to go through all the permutations of lens resolving power limits.. just mentioning they were there  ;)

I recall also the "error function" and it is important in the resolution of
telescope images. I once did some work trying to resolve the discs of stars.
The solution was an array of telescopes first used in radio astronomy. Like
other physics the construction took many years. To see small things you need
very big things over a long integrating time... the search of ET radio
communications is like that. People did not like the observational
results...

physics scares most people.  I don't know why.. it's something I've never stopped learning.  I'm currently reading some of Richard Feynman's memoirs, good for a giggle :)

Science itself is under attack.

i agree with you on that.  A shame people have forgotten that science is a philosophy that has nothing whatsoever to do with qualifications and in fact the concept of qualifications is almost an antitheses to science.

Sorry.. but the little compact digital ... Photography is difficult here,
even people who snap their children have been prosecuted and the thought
police are a reality.

yup, same here in Oz.  Funny thing is that while th propaganda-fed masses revile anyone holding a camera, no one batts an eye at a camera phone.

Art Faul

The Artist Formerly Known as Prints

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