Color waves

I've got these things on my scans which are kinda hard to explain.
They look like when you throw a pebble in the water only waves are all
different colors.

I don't see anything on the glass or the photos so what is that and
how do I get rid of it?

Golden

"Golden Lasky" <goldenlasky@hotmail.com> wrote in message
news:1106056942.445011.99090@f14g2000cwb.googlegroups.com...
> I've got these things on my scans which are kinda hard to explain.
> They look like when you throw a pebble in the water only waves are all
> different colors.
>
> I don't see anything on the glass or the photos so what is that and
> how do I get rid of it?
>
> Golden
>
If you are scanning magazines, what you are seeing is called moiré.
Definition:
Having a wavy or rippled surface pattern

You use the Descreen function of your scanner to get rid of it.

Here is an explanation:
http://www.scantips.com/basics06.html

--
CSM1
http://www.carlmcmillan.com
--

CSM1 wrote:
> If you are scanning magazines, what you are seeing is called moiré.
> Definition:
> Having a wavy or rippled surface pattern

No I'm not scanning magazines. These are just regular photos. The
waves are only in certain places but when I move the photo and rescan
sometimes they move to another place but not always. It's really
weird.

Golden

"Golden Lasky" <goldenlasky@hotmail.com> wrote in message
news:1106056942.445011.99090@f14g2000cwb.googlegroups.com...
> I've got these things on my scans which are kinda hard to explain.
> They look like when you throw a pebble in the water only waves are
> all
> different colors.
>
> I don't see anything on the glass or the photos so what is that and
> how do I get rid of it?

They could be "Newton rings", hard to say for sure without an example.
If it is Newton rings you are looking at, they can be totally
prevented by putting a spacer between film and glass. The colors are
caused by interference between the light and the sub-micron thin layer
of air between two smooth surfaces.

Bart

On 18 Jan 2005 07:42:39 -0800, "Golden Lasky"
<goldenlasky@hotmail.com> wrote:

>No I'm not scanning magazines. These are just regular photos. The
>waves are only in certain places but when I move the photo and rescan
>sometimes they move to another place but not always. It's really
>weird.

If you're scanning glossy photos those are so-called "Newton's rings".
It's light bouncing off of the photograph's surface and canceling out
certain frequencies. Another symptom is a gray ameba-like splotch in
the middle of the rings where the photo literally sticks to the glass.

I've been wrestling with this for a while and if you check the
archives I wrote a message about my workaround less than a week ago.

Basically, you need to keep the photo as flat as possible (I use
double-sided tape to affix it to a piece of Plexiglas) and have it
just a tad above the glass (I put pieces of cardboard around the photo
to lift the Plexiglas).

The problem is you lose some contrast that way but this can be fixed
in postprocessing. (Also, if you have a "contact" scanner like Canon
LIDE series they only focus on the glass surface).

Don.

Bart van der Wolf wrote:
> If it is Newton rings you are looking at, they can be totally
> prevented by putting a spacer between film and glass.

I'm scanning photos not film but what do you mean by a spacer? Can I
use that on photographs too?

Golden

Don wrote:
>If you're scanning glossy photos those are so-called "Newton's rings".
>It's light bouncing off of the photograph's surface and canceling out
>certain frequencies. Another symptom is a gray ameba-like splotch in
>the middle of the rings where the photo literally sticks to the glass.

Yeah now that you mentioned it I see it! I thought that was just dirt
on the picture.

>Basically, you need to keep the photo as flat as possible (I use
>double-sided tape to affix it to a piece of Plexiglas) and have it
>just a tad above the glass (I put pieces of cardboard around the photo
>to lift the Plexiglas).
>

That looks very complicated. Is there maybe an easier way?

Golden

"Golden Lasky" <goldenlasky@hotmail.com> wrote in message
news:1106066291.622933.71570@z14g2000cwz.googlegroups.com...
> Bart van der Wolf wrote:
>> If it is Newton rings you are looking at, they can be totally
>> prevented by putting a spacer between film and glass.
>
> I'm scanning photos not film but what do you mean by a spacer?
> Can I use that on photographs too?

Sure, but it may be harder to prevent a picture from sagging in the
middle than film. You can use e.g. a piece of thin cardboard and cut
out the area you want to scan and position the sandwich of border and
picture in the scanner platen. You can also make a more flexible
solution with two "L" shaped spacers, but it will be hard to align
everything.
Another solution is by non-permanent mounting of the picture to a
rigid background and use something at the corners to create some space
with the glass.

Bart

On 18 Jan 2005 08:48:27 -0800, "Golden Lasky"
<goldenlasky@hotmail.com> wrote:

>Don wrote:
>>If you're scanning glossy photos those are so-called "Newton's rings".
>>It's light bouncing off of the photograph's surface and canceling out
>>certain frequencies. Another symptom is a gray ameba-like splotch in
>>the middle of the rings where the photo literally sticks to the glass.
>
>Yeah now that you mentioned it I see it! I thought that was just dirt
>on the picture.
>
>>Basically, you need to keep the photo as flat as possible (I use
>>double-sided tape to affix it to a piece of Plexiglas) and have it
>>just a tad above the glass (I put pieces of cardboard around the photo
>>to lift the Plexiglas).
>>
>
>That looks very complicated. Is there maybe an easier way?

Yes, use scanning oil or scanning fluid. It is used on drum scanners.
Basically any oily fluid will do, but some will damage your originals.
Clear mineral oil, like lamp oil, is ok.
If you have a lot of scanning to do, consider buying Kami Scanner
Mounting Fluid. It leaves no trace:
>It's a very thin volatile substance similar to
>film cleaner, with kind of a citrus scent. Because it's thin, it flows
>very well, without any of the small bubbles you sometimes get with mineral
>oil. In addition, because it is a volatile compound, it evaporates very
>quickly with almost no residue.

Btw does anybody know a seller of Kami who sells it per *1* bottle?
(In the US.)

regards, wim
--
www.wiskerke.com

On 18 Jan 2005 08:48:27 -0800, "Golden Lasky"
<goldenlasky@hotmail.com> wrote:

>>Basically, you need to keep the photo as flat as possible (I use
>>double-sided tape to affix it to a piece of Plexiglas) and have it
>>just a tad above the glass (I put pieces of cardboard around the photo
>>to lift the Plexiglas).
>>
>
>That looks very complicated. Is there maybe an easier way?

I don't know of any other way. I figured this out myself. Perhaps
someone else can chime in?

Don.