Why the purple blue snow when projecting film?

What you are seeing is more than likely the grain of the film itself. Just
like with a video camcorder in low light situations film, when shot under
wrong conditions, produces a grainy image. At least that's what I gather is
happening from your description. Post a still from the films somewhere so we
can see exactly what you are talking about.

--
Larry Johnson
Digital Video Solutions
webmaster.TakeThisOut@digitalvideosolutions.com
http://www.digitalvideosolutions.com

"Serving Boston and New England from our offices in beautiful downtown New
Bedford, Massachusetts!"
877-227-6281 Toll Free Sales Assistance
774-202-3512 Customer Service
508-990-1398 Fax


"Doc" <docsavage20.TakeThisOut@xhotmail.xom> wrote in message
news:PDMVg.8310$o71.3411@newsread3.news.pas.earthlink.net...
>I notice when doing transfer of film to avi/DVD, there's a purple - blue
> "snow" in the projected image that's particularly visible against lighter
> backgrounds. It's not a digital artifact, you can see it on the projected
> image too. What causes this? Is there a Virtualdub filter to remove or
> reduce it without effecting the overall image?
>
> Thanks
>
>
 >> Stay informed about: Why the purple blue snow when projecting film? 

On Sat, 07 Oct 2006 11:58:39 GMT, "Doc" <docsavage20.RemoveThis@xhotmail.xom> wrote:

>I notice when doing transfer of film to avi/DVD, there's a purple - blue
>"snow" in the projected image that's particularly visible against lighter
>backgrounds. It's not a digital artifact, you can see it on the projected
>image too. What causes this?

What you describe is purple fringing, something typical of cheap lenses:
http://www.pictureline.com/newsletter/2004/july/purplefringe.html

>Is there a Virtualdub filter to remove or
>reduce it without effecting the overall image?

In stills-software, yes, but for moving images? No Idea.

cheers

-martin-
--
 >> Stay informed about: Why the purple blue snow when projecting film? 

"Richard Crowley" <rcrowley.DeleteThis@xpr7t.net> wrote in message
news:12ifc77438a0m25@corp.supernews.com...
> "Doc" wrote ...
> >I notice when doing transfer of film to avi/DVD, there's a purple -
> >blue
> > "snow" in the projected image that's particularly visible against
> > lighter
> > backgrounds. It's not a digital artifact, you can see it on the
> > projected
> > image too.
>
> Since this is clearly not a video question (by your own
> admission),

I don't recall "admitting" any such thing. Since I'm doing video capture it
seems logical some in the video forum likely have similar experience. If you
disagree, okay. I'm still going to post the question here but I'm sure you
feel much better now.
 >> Stay informed about: Why the purple blue snow when projecting film? 

"Martin Heffels" <feipbjszfo.TakeThisOut@oxeszdjnlp.xercdpvueppjtmougcqvtz.net> wrote in
message news:s06fi258ek2h9hesst5aqia7bpc3ge5nin@4ax.com...
> On Sat, 07 Oct 2006 11:58:39 GMT, "Doc" <docsavage20.TakeThisOut@xhotmail.xom> wrote:
>
> >I notice when doing transfer of film to avi/DVD, there's a purple - blue
> >"snow" in the projected image that's particularly visible against lighter
> >backgrounds. It's not a digital artifact, you can see it on the projected
> >image too. What causes this?
>
> What you describe is purple fringing, something typical of cheap lenses:
> http://www.pictureline.com/newsletter/2004/july/purplefringe.html

From the description, this isn't what I'm talking about. It's like the image
is filled with a zillion little purpleish/blueish/whiteish speckles or
grains of sand. Again, it's visible in the original projected image as seen
by eyeballs before it ever hits the camera. It's most obvious against
whitish/grayish areas that aren't too bright.
 >> Stay informed about: Why the purple blue snow when projecting film? 

"Doc" <docsavage20.RemoveThis@xhotmail.xom> wrote in message
news:lVYVg.11404$UG4.11063@newsread2.news.pas.earthlink.net...
>
> "Martin Heffels" <feipbjszfo.RemoveThis@oxeszdjnlp.xercdpvueppjtmougcqvtz.net> wrote
> in
> message news:s06fi258ek2h9hesst5aqia7bpc3ge5nin@4ax.com...
>> On Sat, 07 Oct 2006 11:58:39 GMT, "Doc" <docsavage20.RemoveThis@xhotmail.xom> wrote:
>>
>> >I notice when doing transfer of film to avi/DVD, there's a purple - blue
>> >"snow" in the projected image that's particularly visible against
>> >lighter
>> >backgrounds. It's not a digital artifact, you can see it on the
>> >projected
>> >image too. What causes this?
>>
>> What you describe is purple fringing, something typical of cheap lenses:
>> http://www.pictureline.com/newsletter/2004/july/purplefringe.html
>
> From the description, this isn't what I'm talking about. It's like the
> image
> is filled with a zillion little purpleish/blueish/whiteish speckles or
> grains of sand. Again, it's visible in the original projected image as
> seen
> by eyeballs before it ever hits the camera. It's most obvious against
> whitish/grayish areas that aren't too bright.

If it's on the film, it sounds like reticulation -- caused by improper
processing of the film, e.g. chemicals too warm or too cold. It could also
simply be grain, or deterioration of the film with age. What kind of film
is it? Kodachrome is very unlikely to experience reticulation or display
this kind of deterioration -- it used a dye-replacement process that stands
up very well. Ektachrome, on the other hand, can show all kinds of
deterioration-related symptoms. I've transferred 50-year old Kodachrome
that looked as pristine as the day it was shot. On the other hand, I've had
20 year old Ektachrome that was completely unviewable.

>
>
 >> Stay informed about: Why the purple blue snow when projecting film? 

On Sun, 08 Oct 2006 01:56:33 GMT, "Doc" <docsavage20.TakeThisOut@xhotmail.xom> wrote:

>From the description, this isn't what I'm talking about.

If possible, can you put up a still so we can have a look?
Better than having all of us making wrong guesses :-)

cheers

-martin-
--
 >> Stay informed about: Why the purple blue snow when projecting film? 

"Digital Video Solutions" <webmaster.DeleteThis@digitalvideosolutions.com> wrote in
message news:J96dnfwqQbz8MbrYnZ2dnUVZ_uydnZ2d@comcast.com...
> What you are seeing is more than likely the grain of the film itself. Just
> like with a video camcorder in low light situations film, when shot under
> wrong conditions, produces a grainy image. At least that's what I gather
> is happening from your description. Post a still from the films somewhere
> so we can see exactly what you are talking about.


I concur.
 >> Stay informed about: Why the purple blue snow when projecting film? 

"PTravel" <ptravel DeleteThis @travelersvideo.com> wrote in message
news:4osfjaFg7bkiU1@individual.net...
>
> If it's on the film, it sounds like reticulation -- caused by improper
> processing of the film, e.g. chemicals too warm or too cold. It could
> also simply be grain, or deterioration of the film with age. What kind of
> film is it? Kodachrome is very unlikely to experience reticulation or
> display this kind of deterioration -- it used a dye-replacement process
> that stands up very well. Ektachrome, on the other hand, can show all
> kinds of deterioration-related symptoms. I've transferred 50-year old
> Kodachrome that looked as pristine as the day it was shot. On the other
> hand, I've had 20 year old Ektachrome that was completely unviewable.
>
Are you sure he is talking about a real film?
Or just a video being called a film?
If it wasn't shot on Film, then is it OK now to call it a film anyway?
A few years ago, it was blastphomy to call anything that involved
computers or electronic media a FILM.
AFAICT the newer Star Wars movies are just videos.
Have we reached "anything goes" yet?
You go to Blockbusters to rent video, not film, not even tapes.

David
 >> Stay informed about: Why the purple blue snow when projecting film? 

"David McCall" <david_____ RemoveThis @techshop.net> wrote in message
news:Sn8Wg.1709$WD1.1543@trndny04...
>
> "PTravel" <ptravel RemoveThis @travelersvideo.com> wrote in message
> news:4osfjaFg7bkiU1@individual.net...
>>
>> If it's on the film, it sounds like reticulation -- caused by improper
>> processing of the film, e.g. chemicals too warm or too cold. It could
>> also simply be grain, or deterioration of the film with age. What kind
>> of film is it? Kodachrome is very unlikely to experience reticulation or
>> display this kind of deterioration -- it used a dye-replacement process
>> that stands up very well. Ektachrome, on the other hand, can show all
>> kinds of deterioration-related symptoms. I've transferred 50-year old
>> Kodachrome that looked as pristine as the day it was shot. On the other
>> hand, I've had 20 year old Ektachrome that was completely unviewable.
>>
> Are you sure he is talking about a real film?

No, but it made the most sense.

> Or just a video being called a film?

He talked about the problem being visible when it was optically projected,
before being captured to DV.

> If it wasn't shot on Film, then is it OK now to call it a film anyway?
> A few years ago, it was blastphomy to call anything that involved
> computers or electronic media a FILM.

I have no opinion either way. If he's talking about chemical film, it sound
likes reticulation or deteroriated Ektachrome.


> AFAICT the newer Star Wars movies are just videos.
> Have we reached "anything goes" yet?
> You go to Blockbusters to rent video, not film, not even tapes.
>
> David
>
 >> Stay informed about: Why the purple blue snow when projecting film? 

It sounds like the film might be turning red (certain stocks do that),
and that you're also picking up a lot of grain. "Fixing" it? Not so easy.
You can try the virtualdub noise reduction filters (such as median, or
some of the smart smoothers), but there is no magic bullet. Noise
reduction usually has side effects.

In rec.video.desktop Doc <docsavage20.DeleteThis@xhotmail.xom> wrote:
: I notice when doing transfer of film to avi/DVD, there's a purple - blue
: "snow" in the projected image that's particularly visible against lighter
: backgrounds. It's not a digital artifact, you can see it on the projected
: image too. What causes this? Is there a Virtualdub filter to remove or
: reduce it without effecting the overall image?

: Thanks
 >> Stay informed about: Why the purple blue snow when projecting film?