[PRCo] Re: Call Me Crazy...

[Fred Schneider]

The moire (pronounced more - A) pattern happens because the dots in  
the engraving collide with the dots in the second reproduction.   It  
can be eliminated by twisting the halftone screen at a different  
angle to that of the original screen ... I should say can sometimes  
be eliminated.   It becomes more difficult when trying to reproduce  
something that was done in color the first time because there are  
three (magenta, cyan and yellow or red, blue and green) sets of dots  
(or fours sets (sometimes a black screen is used for higher quality  
(deeper shadows), and you may get the moire out of several of the  
layers but not all of them.     Now, if you are trying to reproduce  
an original set of color separations, you will photograph it through  
three or four times through color filters so that each set of film  
picks up the dots from only one layer, and it is much easier to solve  
the moire problem then.   Of course, in that instance, you are paying  
for expertise and quality.

There were a couple of instances in Headlights magazine, back in the  
1970s when Howard White and I were editing it, when we pirated  
uncopywrited newspaper pictures.   We did it without rescreening them  
simply by reducing the size 50% and using the original screening from  
the newspaper (they were using something like a 50 dot per inch  
screen and we were normally using 100 dots per inch).   It worked  
beautifully.   No moire problems.   Improved sharpness.   It's called  
thinking outside the box!

On Jun 8, 2006, at 7:27 PM, Bob Rathke wrote:

> I took hundreds of photos on the Northside from 1963-66, and never  
> got any
> cross-hatch photos, but then I was shooting color slide film.
>
> The moire pattern shows up when you scan a halftone print, such as  
> a printed
> page.  Photographs have a continuous tone, so the pattern doesn't  
> happen
> when you scan a photoprint...but maybe the scanner used for the  
> North Side
> photo was on the wrong  scan setting.
>
> Bob 6/8/06
>
> -----------------------------
> ----- Original Message -----
> From: "Ken & Tracie" <ktjosephson at earthlink.net>
> To: <pittsburgh-railways at dementia.org>
> Sent: Thursday, June 08, 2006 8:19 AM
> Subject: [PRCo] Call Me Crazy...
>
>
>> ..but what is it with Routes 10-15 and this crazy cross hatch  
>> pattern in
>> this print???
>> Roberta Hill photpgraphed this line in '62, '63 and during the  
>> line's last
>> week. Nearly all her pix along this section of the system have that
>> cross-hatch or woven dot look to them. So does some of the footage in
>> TGM's video of this line.
>>
>> Anybody else have this problem with camera film when photographing  
>> this
>> line?
>>
>> Is it possible some weird military experiments were going on in  
>> the area
>> that may have caused visual "noise" in camera film? Microwave towers?
>> Activity at the Nike site?
>>
>> Any "cancer clusters" in the area since the 1960s?
>>
>> K.
>>
>> -- Attached file removed by Ecartis and put at URL below --
>> -- Type: image/pjpeg
>> -- Size: 55k (56494 bytes)
>> -- URL : http://lists.dementia.org/files/pittsburgh-railways/ 
>> p0062.jpg
>>
>>
>>
>
>