Micro Contrast

[gcha]

I would like to learn/know how to achieve what I would call Micro Contrast in my images. What I am talking about are dark images where small highlights are brightened in the images in a uniform manner, and appear to be crisp and sharp. I have been using the dodge/burn tools, but this takes a long time, and is very tedious. Also, the highlights seem to always be a bit 'gray' and not sparkling white. I am using PWP 3.5 and process/ print to B&W. I have tried increasing contrast and color saturation in color, before conversion to B&W, with some success, and have used some USM to add contrast and sharpness to those areas of dark to light transitions.
Thanks,
Gary

[JML]

Gary:

Its difficult to be specific w/o an image, but here are a few general suggestions:

Pulling the WP to the left using HSV or RGB curves increases contrast and increases brightness mostly the lighter areas with less effect on the darks.

A high radius – low amount sharpening (generally known as Local Contrast Enhancement or LCE) will add punch and also has a sharpening effect. If the images are dark and you don’t want to increase the dark side of sharpening halos, you can apply USM or the LCE version and then composite the result to the original in Lighten mode. That way the darkening side of the USM coin is left behind.

One reference on LCE by Ctein is:

http://theonlinephotographer.typepad.co ... rove-.html

I haven't used LCE in years because I prefer to paint contrast increasing cuves locally into the image. But it works.

Jim

[jsachs]

You might want to try Bilateral Sharpening - see the white paper Sharpen.pdf.

[gcha]

Thanks for the suggestions.
JS, I read the Sharpen.pdf and was wondering how the work flow is supposed to work. What are the steps that are used and in what order for this bilateral work flow? Is there a specific selection in the USM dialogue box?
Thanks

[jsachs]

Bilateral Sharpening is one of the sharpening methods available in the Sharpen transformation. The effects of the various parameters are described in detail in the latest version of Sharpen.pdf. All sharpening can be thought of as micro contrast enhancement as it lightens the lighter pixels and darkens the darker ones based on the region surrounding each pixel. Bilateral sharpening has the advantage of not making halos around edges as much as other methods.

[den]

Gary...

Bilateral Sharpening is available in PWP5. In your OP, you indicate that you are still using PWP3.5. You may want to test drive a PWP5 trial. There are additional features that may be of help to make your BW conversions easier... for example: (1) there is a 'Channel Mixer' method in the Monochrome transform and (2) the 'Texture' of the Mask Tool will help in quickly finding edges for sharpening [the sliders can be adjusted for large edges or small edges with different methods to find the edge or perhaps a 'speck'].

As Jim suggested... creating perhaps an overly sharpen image version by whatever method available in PWP3.5 and then Composite-Lighten to a preference Amount with an Edge mask may be more expedient... but also if there was an illustration available, one could perhaps more directly address the issue...

[den]

Happen to think of something else that might work and is doable with PWP3.5....

Use the Filter transform in either Additive/Subtractive mode with an 'active' image area mask where the image is filtered with itself with a boosted ExposureCompensation....

Illustrated below is the left side of a wave top contrast increase where the Filter transform was used with a mask in Additive mode with an EC=2.0 with a preference mask white amount...

Mask-AddFilter+EC.jpg (44.08 KiB) Viewed 10017 times

[Robert Schleif]

Here in order of increasing complexity, are six ways of increasing local contrast. Normally, I use number one, but when I need to push it, I use numbers five or six.
1. Unsharp mask, radius 100 (on the order of the sizes of objects), amount, 20-40%.
2. Blur with radius on the order of the sizes of objects, subtract 20-40% of this from original, restore normal intensity range with gray-brightness curve. (This is, in fact the same as the USM procedure, #1, you just have more control.
3. Convert to 8 bit B&W, expand this to full range, use this as mask of original with gray-brightness curve. A good starting point for this is [0,0], [20,0], [80,100], [100,100] with the black and white sliders at 50.
4. Filter transformation, additive or subtractive, using the image itself as the filter, exposure compensation ~1.12. It may be good to use a midrange mask so as to exclude blowing the highlights and sinking the shadows.
5. Use the two-tone or three-tone transformation tool (PW 5)
5. Den’s three-tone procedure
See http://www.ncplus.net/~birchbay/3tone/3tone.htm
Mask shadows, midtones, highlights.
Highlight for example, using brightness curve with points at [0,0], [b,0], [b+10.100], [100,100]. Blur with radius 35-100, subtract brightness curve [0,100], [b-20,100], [b,0], [100,0], feather –2, feather + 2, expand to full range if necessary.
Similar procedure for shadows using a. Midtones, use a and b.
Brightness adjustment
Highlights, use HSL color space, add control point at [50,50] move to between [50,40] and [50,30].
Shadows, use HSV color space, move [100,100 ]to left until halos form, typically about [70,100], then move point [12,30] for best contrast.
Midtones, use HSV or RGB set points [30,30] and [70,70], move to, e.g. [30,20], [70,80].

[Charles2]

Would the technique suggested by Andy Blankertz belong on Robert's list?
http://www.dl-c.com/cgi-bin/discus/show ... #POST27134

Here is a slightly refined version I often use (I have PWP5):

• Extract luminance or HSL-L channel.
  Blur it high-pass, typically radius 3 to 5.
  Do a simple sharpen on the result, reducing default radius 2 to 1. (Stumbled on this; does it add anything or have I fooled myself?)
  Use it as overlay in a Filter of the image, exposure compensation 1.36
  Adjust amount as needed, typically 20 to 25 percent.

[MikeG]

Here's a link to a free (but functionally limited) highly interactive stand alone Local Contrast Enhancement program:

http://members.chello.nl/r.kroonenberg2 ... wnload.htm

the link also provides access to a noise reduction program.

It's for the adventurous as there is very little documentaion and not a proper web page. I've installed it - it's fun, at the very least. May be best to 'run as administrator' under Vista.

Mike.