Archived posting to the Leica Users Group, 2003/03/11

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

Subject: [Leica] Help: Contrast management in Photoshop
From: Martin Howard <mvhoward@mac.com>
Date: Tue, 11 Mar 2003 11:44:10 -0800

I have a problem that occurs relatively frequently and I'm hoping that 
some of the Photoshop wizards among you can help me out.

Occasionally, I need to increase contrast locally in an image.  For 
example, the face in an environmental portrait may be a bit flat, i.e. 
it only spans a few levels from the darkest to the lightest pixels.  In 
a darkroom, you'd fiddle this with dodging and burning typically 
combined with a different grade contrast filter on VC paper.

However, in Photoshop, I'm lost.  What I'd ideally like to do is get 
Photoshop to do is two things: pull apart the end points in a local 
region (masked off by a selection) and then "fill in the blanks" in the 
resulting histogram so that I get a smooth tonal gradation and no 
posterization.

Is there any way of accomplishing this?


I suspect there is -- because I've noticed something else interesting.  
I've taken to do a quick preview of my scans using "Preview" (the Apple 
application bundled with OS X).  It manages to do something remarkable: 
When you first load an image, it looks grainy and harsh, with 
semi-posterized areas.  But after about a second of calculations, it 
smooths out the tonal transitions, seemingly without loosing detail.  
The result is something that looks a hell of a lot more photographic 
than it did originally.  Since this is step two of the process outlined 
above -- and something that I'd love to be able to do in PS -- how is 
it accomplished?

M.

- --
To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html

Replies: Reply from Daniel Ridings <daniel.ridings@muspro.uio.no> (Re: [Leica] Help: Contrast management in Photoshop)