Re: [APML] Histograms

["Eddie Guscott" <eddie.guscott@blueyonder.co.uk>]

Alan

This is what I did (using a Minolta Dimage Scan Dual II scanner)

Set scanner to scan at 16 bit depth (which produced an image of 60MB!!!)
After doing an index scan, and before final scan I made adjustments to
levels to bring the
histogram into a nice "hill/mountain", tapering off to the right a bit(this
is teknikal, isn't it!).

I then scanned at 16 bit and saved as TIFF.

Opened this 60MB in PS and looked at histogram (bear in mind I've already
done some
levels adjustment prior to scanning) and the histogram is a solid lump
although it was clipped (I didn't
know it was clipped however, until looking at Matt ben Daniels article on
curves. Howvwer, I don't
know yet what caused the clipping!!!)

The histogram was very nearly at the left hand side so i adjusted the gamma
(this was tricky, cos I couldn't find
this adjustment in PS - finally found it in Image Ready programme which
accompanies Photoshop).

Final result was a solid histogram, starting about a quarter way in from the
left, rising to a peak (hill top)
and then tapering off.

Saved this as a 8 bit image in PS format (***.psd) and then proceed to
adjust curves.

After messing with curves a little, the histogram did not "picketfencealise)
but stayed fairly solid (I
assume this means I haven't lost too much information).

However, if you look at my earlier post, I don't know how you can spend 30
minutes on
curves. What are people doing for half an hour - that's what I want to know.

Hope this helps

With some perseverance, we'll get to the bottom of this.

Rather that a net meeting thing, my suggestion would be that Matt or Tony or
someone, produce a video
(camera pointed pointed over their shoulder at the monitor) and capture
everything that's done to an image.
This could then be sold to PS idiots like us for USD25 a time. (might be
nice sideline for someone)

Regards

Eddie Guscott

----- Original Message -----
From: "Alan Voetsch" <critter12952@yahoo.com>
To: <astro-photo@seds.org>
Sent: Monday, April 29, 2002 9:27 PM
Subject: Re: [APML] Histograms


> --- Eddie Guscott <eddie.guscott@blueyonder.co.uk>
>  I've tried
> > rescanning at 16 bit and doing some levels
> > adjustments at the scanning stage
> > and my histograms
> > are no longer picket fence posts.
>
> Hey Eddie,
>
> OK, now give. What adjustments have you made at the
> scanner? I know you're holding out on me! :-))
>
> Alan
>
>
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