Digital BW, The Print

Good point Barry. Always to good to double check these things.

Mike


----- Original Message -----
From: "bggilliand2001" <bgilliand@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Sunday, March 24, 2002 12:34 PM
Subject: Re: [Digital BW] PhotoShop Histograms leading us astray?


> Maybe obvious to most, but for new users be sure that the "use cache
> for histograms" is not checked in general preferences. If this box is
> checked, PS will display the histogram faster, but the info is based
> on a representative sampling of pixels instead of all the pixels.
> Access preferences under "edit" on the PC and select "Memory and
> Image Cache", and unchek the box. Also set to levels of cache and
> memory allotment here. You can also display a histogram using all
> image pixels by pressing the shift key while choosing
> Image>Histogram. If you've reset your preferences lately, may want to
> check it out. Timely info from Carla Rose in the latest issue of
> Photoshop User.
>
> Barry Gilliand
>
> --- In DigitalBlackandWhiteThePrint@y..., "Michael Kravit"
> <michael.kravit@w...> wrote:
> > Barry,
> >
> > If you create a gradient in PS and then posterize it creating 21
> distict
> > patched you get a histogram with 21 vertical lines. This is because
> the
> > image is no longer a gradient.
> >
> > Now, if you create a second gradient without posterizing it so that
> it is as
> > smooth as Photoshop can make it you will have a histogram that is
> sold with
> > a gradual arc that is high at the ends and slopes down a bit in the
> center.
> >
> > There may be roughness at the top along the curve, but you do not
> have deep
> > fingers indicating that data is missing.
> >
> > Mike
> >
> >
> > ----- Original Message -----
> > From: "flyfishingusa2002" <tflyfish@c...>
> > To: <DigitalBlackandWhiteThePrint@y...>
> > Sent: Sunday, March 24, 2002 11:08 AM
> > Subject: [Digital BW] PhotoShop Histograms leading us astray?
> >
> >
> > > I have been following all the threads regarding "Combing"
> and "Step-
> > > Wedges" with great interest. I have been looking at there
> Histograms
> > > in Photoshop and trying to figure out what it was telling me. I
> have
> > > been seeing a lot of "stray" information in the Histograms that
> > > confused me, so I decided to try the following:-
> > >
> > > 1  I did a selection of just the wedge part of the published
> > > standard Step wedge by Jon Cone and MIS
> > >
> > > 2  I, via PhotoShop 6, drew a simple rectangle filled with a
> > > graduation from 0% - 100% grey.
> > >
> > > Neither of the above gave me a "Clean" Histogram. I fully expected
> > > #2 to do so. I see lots of little comb teeth and a variation in
> the
> > > histogram height when I thought it should be constant.
> > >
> > > Could it be that the "Combing" is something that Photoshop is
> > > introducing and does not really appear on our finished print?
> > >
> > > I have also noticed that on the step wedge that those little white
> > > dividing lines do not appear between all the steps on some
> > > magnifications and not on others.
> > >
> > > I am no PhotoShop expert, but the above seems a little odd, maybe
> we
> > > are all being lead astray by PhotoShop?
> > >
> > > Barry
> > >
> > >
> > >
> > > Please visit the Group Homepage to check the Files, Bookmarks,
> Polls and
> > other resources as they are often being updated. The page is at:
> > >
> > > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> > >
> > > Please follow these basic guidelines:
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> > >
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>
>
>
> Please visit the Group Homepage to check the Files, Bookmarks, Polls and
other resources as they are often being updated. The page is at:
>
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
>
> Please follow these basic guidelines:
> - Include your full name with your message.
> - Include the address of your website, if you have one.
> - As threads develop, trim off excess portions of earlier messages to keep
them short.
> - As the topic of a thread changes remember to change the subject header.
> - Good manners are required at all time. No personal attacks or "flames."
> - Complete your Yahoo profile.
> - Before posting a question, search the message archives and the various
resources on the homepage.
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>