Archived posting to the Leica Users Group, 2001/03/12

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: [Leica] Trying to improve my scans
From: Doug Herr <>
Date: 12 Mar 2001 11:03:11 -0800

On Mon, 12 March 2001, Nathan Wajsman wrote:

> Hi Tim,
> Let's hear about your technique, I would benefit too. I usually use the
> middle slider to get the overall exposure right (if needed), and then move
> the two extreme sliders a bit towards the middle to increase contrast
> (again, when needed). The amount of movement is determined by the
> histogram: I try to move the black slider to the point where the histogram
> starts rising, and the white slider to the point where it almost touches
> the horizontal axis.
> Nathan

PMFJI - for B&W, I always set the black and white points before messing with the middle slider.  I set the white point so that the brightest areas where I want detail are about 250 or so.  I'll let specular highlights such as sunlight reflecting off the water go to 255, so there's no fixed formula for where the white slider meets the histogram curve.  Similar for black point: I set the black slider so that the darkest areas that have detail are about 10, letting detail-less blacks go to zero if that's where they fall.  Once the black and white points are set I'll adjust the mid tones.

The procedure's very much the same for color images, adjusting each of the red/green/blue curves for white point and black point, using the middle sliders of each channel to adjust color balance.  The last adjustment is the middle slider of the overall histogram, which adjusts overall mid-tones as with a B&W image.

Doug Herr
Birdman of Sacramento
The ALL NEW CS2000 from CompuServe
 Better!  Faster! More Powerful!
 250 FREE hours! Sign-on Now!

Replies: Reply from Nathan Wajsman <> (Re: [Leica] Trying to improve my scans)