Brightness Curve Detail Control Explained

[tomczak]

Here is a quote from Jonathan, explaining how the new Brightness Curve Detail Control works, for future reference:

The way it works is to split the input image into two components - a low pass (blurred image created as in bilateral sharpen) and a high pass image (computed by subtracting the low pass image from the input image). The low pass image captures the overall tonal variations while the high pass image captures the details. The brightness curve is applied to the low pass image and then the high pass image is added back in to create the output image. The idea is that the tonal variations can be applied to the input image while preserving its local contrast.

[johnp]

Maciej -

Have you had a chance to play with the new feature? Does it look promising?

It would be nice if DL&C (or someone) would make a tips page with tidbits on this feature and
other things (like the quick & easy slide show feature).

Thanks for all your good posts.

John P

[den]

A fellow PWP user ask me about 'Clarity'... ...this was my reply:

PWP's equivalent to +/- Clarity seems to be PWP v7.0.17's BrightnessCurve 'Detail Control: Yes' feature...

1) Open the Brightness Curve transform with a selected Input image...
2) leave Color Space [HSV] and Curve [0,0 to 100,100 default diagonal] at their defaults with transform Amount = 100 and no Amount mask...
3) set Detail Control to Yes...
4) to add "clarity" (increase detail), use the suggested Detail Control settings for Radius and Threshold, and adjust the Detail slider to a preference [perhaps between 1.15 to 1.35] while monitoring a 1:1 Preview or do a transform Apply to more fully evaluate the setting...
5) to subtract "clarity" (skin smoothing), use perhaps Detail Control settings: Radius = 10; Threshold = 20%, and adjust the Detail slider to a preference [perhaps between 0.50 to 0.80] while monitoring a 1:1 Preview or do a transform Apply to more fully evaluate the setting... ...for 'skin smoothing', one could use an image area mask of the skin as an Amount Mask where the skin area is 100% white and non-skin areas are 0% black.

Detail Control seems to be independent of the transform's Color Space selection functioning in the RGB color space as do most sharpening and/or 'local contrast enhancement' techniques and is fully applied to the Input image with a Brightness Curve transform 'default' curve, no mask, and Amount = 100... ...Detail settings above 1.00 will add detail and settings below 1.00 will decrease detail.

An approach for determining initial Detail Control settings:
1) Brightness Curve transform with Input image and default color space, default curve, and Amount = 100... ...Detail Control: Yes; Radius = 0; Threshold = 100; and Detail = 0.00... ...while monitoring an updating Preview...
2) increase Radius to a preference, bluring major image detail and edges
3) decrease threshold to a preference to retain desired major edges
4) increase Detail slider from 0.00 to preference detail smoothing or sharpness
5) turn on, then off, and repeat "Show clipped pixels" to avoid excessive highlight and/or shadow blocking

Have fun experimenting...
...den...

[den]

Addendum to the above post...

You can further 'fine' control edge highlight and/or shadow blocking when increasing detail with a Stair Step Mask = [0,0] [50,0] [50,100] [100,100] applied to the Input image as described in this tip posting here: http://www.dl-c.com/board/viewtopic.php?f=5&t=1020 while using on/off/repeat "Show clipped pixels'.

...den...