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compression artefacts by film lab?

 
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user1373

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Since: Nov 16, 2004
Posts: 1



(Msg. 1) Posted: Tue Nov 16, 2004 7:07 pm
Post subject: compression artefacts by film lab?
Archived from groups: rec>photo>film+labs (more info?)

I had a film developed and printed by an AGFA photolab and remarked an
artefact: a part of the picture was solid red, and it seemed to me like on
the edges of the red part artefacts were visible, similar to what you get
when doing JPEG-compression on digital images. Is it possible that film
labs scan the negative from film, compress it and deliver a print based on
the digital image? Or can an old-fashioned development process also
introduce artefacts on surfaces that have a solid colour?

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dooey

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Since: Jun 05, 2004
Posts: 24



(Msg. 2) Posted: Wed Nov 17, 2004 12:32 am
Post subject: Re: compression artefacts by film lab? [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

"vicmortelmans" <vic.mortelmans.TakeThisOut@vlaanderen.org> wrote in message
news:ea94c9a2fda250987568a85b8ce8d53f@localhost.talkaboutphotography.com...
 > I had a film developed and printed by an AGFA photolab and remarked an
 > artefact: a part of the picture was solid red, and it seemed to me like on
 > the edges of the red part artefacts were visible, similar to what you get
 > when doing JPEG-compression on digital images. Is it possible that film
 > labs scan the negative from film, compress it and deliver a print based on
 > the digital image? Or can an old-fashioned development process also
 > introduce artefacts on surfaces that have a solid colour?
 >

The majority of high street labs are now digital. Perhaps you could post a
link to an image of your problem.

--
Dooey.<!-- ~MESSAGE_AFTER~ -->

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can

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Since: Sep 16, 2004
Posts: 206



(Msg. 3) Posted: Wed Nov 17, 2004 11:17 am
Post subject: Re: compression artefacts by film lab? [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

vicmortelmans <vic.mortelmans RemoveThis @vlaanderen.org> wrote:
 > I had a film developed and printed by an AGFA photolab and remarked an
 > artefact: a part of the picture was solid red, and it seemed to me like on
 > the edges of the red part artefacts were visible, similar to what you get
 > when doing JPEG-compression on digital images. Is it possible that film
 > labs scan the negative from film, compress it and deliver a print based on
 > the digital image? Or can an old-fashioned development process also
 > introduce artefacts on surfaces that have a solid colour?

Was it an Agfa d-Lab.2 or an older (optical) Agfa MSC lab?

The Zeta printer in the d-Lab.2 can print from both TIFF and JPEG.
The high-res scans that I get from d-Lab.2 are relatively high-Q JPEG,
so I doubt you would be able to see JPEG artifacting in 4x6 prints.
Although it's possible the lab operator can turn down Q-level.<!-- ~MESSAGE_AFTER~ -->
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jeremy2

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Since: Dec 01, 2004
Posts: 200



(Msg. 4) Posted: Tue Nov 30, 2004 9:23 pm
Post subject: Re: compression artefacts by film lab? [Login to view extended thread Info.]
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"vicmortelmans" <vic.mortelmans.DeleteThis@vlaanderen.org> wrote in message
news:ea94c9a2fda250987568a85b8ce8d53f@localhost.talkaboutphotography.com...

 >Is it possible that film
 > labs scan the negative from film, compress it and deliver a print based on
 > the digital image?

Absolutely!

Kodak offers this service in the US, under their trade name "Perfect Touch."
You can get the details at their web site.

The film is processed, then scanned, and then various digital corrections
are applied. The image files are then printed pixel-by-pixel onto silver
halide paper, that is processed in chemicals, just as a regular photo print.

This process is good for amateur prints that might need some tweaking to
brighten shadowy areas, etc. And, since the print is not made by projecting
an image onto the paper by an enlarging lens, the various types of
distortion that would ordinarily be introduced by a cheap enlarging lens
are, at least in theory, not present.

It makes little sense to use fine lenses and then have your film processed
by a lab that uses enlarging lenses that are not up to the optical quality
of your own lenses. The mail-order lab that I often use, <a style='text-decoration: underline;' href="http://www.dalelabs.com," target="_blank">www.dalelabs.com,</a>
uses Nikkor enlarger lenses that cost $10,000.00 each.<!-- ~MESSAGE_AFTER~ -->
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