Local Contrast Enhancement

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den
Posts: 856
Joined: April 25th, 2009, 6:33 pm
What is the make/model of your primary camera?: Canon EOS-350D/Fuji X100T
Location: Birch Bay near Blaine, WA USA

Re: Local Contrast Enhancement

Post by den »

...

As has previously mentioned, for the current PWP v7.0.19 Sharpen - Bilateral Sharpen transform only has a maximum Blur radius of 20, yet JS's white paper has examples with settings greater than this... ...the Blur radius range is to be increased in a future release.

The following is a suggested work around if you wish to explore 'effective' Blur ranges greater than 0 to 20:
...(a) downsize the intended Input image by 50% will provide an 'effective' 0 to 40 Blur Radius with a transform setting of 0 to 20...
...(b) downsize the intended Input image by 33% will provide an 'effective' 0 to 60 Blur Radius with a transform setting of 0 to 20...
...(c) downsize the intended Input image by 25% will provide an 'effective' 0 to 80 Blur Radius with a transform setting of 0 to 20...

For example, (1) the image: DSCF1289.tiff [4896x3264pixels, 48 bits] was downsized by 33% with the Resize transform and Bicubic method; (2) Sharpen-Bilateral Sharpen LCE was performed at a Blur Radius = 60 with other preference settings on the downsized image; (3) the LCE image version was upsized by 300% to its original dimensions using Resize and the Bicubic method...

An image area of the Starting image modified for posting...
ScrnView(22)_Ori.jpg
ScrnView(22)_Ori.jpg (97.3 KiB) Viewed 2203 times
The LCE image area of the Final image with the same modifications for posting...
ScrnView(22)_BS-LCE_Radius60.jpg
ScrnView(22)_BS-LCE_Radius60.jpg (128.12 KiB) Viewed 2204 times
...an apparent benefit to the downsize and upsizing seems to be smoothing of small noise artifacts allowing one to use higher values of Sharpen Factor's then is suggested in JS's white paper...

Something else that has merit is to 'over cook' the upsized LCE image version and then: preference Composite-Blend and/or 1:1 Clone image areas from it to the original Starting image...

...have fun experimenting...
...den...
tomczak
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Joined: April 25th, 2009, 12:56 am
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Re: Local Contrast Enhancement

Post by tomczak »

I've been doing something similar with AS, not knowing the name for it...

I always wandered why I usually liked the results using AS more than BS. It may have something to do with the 'un-thresholded' blurring step producing different results.

The advantage of BS is that it seems faster than it used to be, and also faster than AS for large radii.
Attachments
AS 16
AS 16
300 Crop AS Blur 16.jpg (11.68 KiB) Viewed 2129 times
BLS R20
BLS R20
300 Crop BLS Blur 20.jpg (10.49 KiB) Viewed 2127 times
Original
Original
300 Crop Original.jpg (43.79 KiB) Viewed 2124 times
Maciej Tomczak
Phototramp.com
tomczak
Posts: 1367
Joined: April 25th, 2009, 12:56 am
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Re: Local Contrast Enhancement

Post by tomczak »

Just out of curiosity, 3 different blurs of the original crop of Jonathan's image, with radius 16. The radii may not mean the same thing between the blurring methods, I imagine, but the results are visually different because of the blur computations, not only the amount of blur.

c.f. AS and the original from the previous post.
Attachments
Bilateral Sharpen 16 (blur)
Bilateral Sharpen 16 (blur)
BLS Blur 16.jpg (11.41 KiB) Viewed 2115 times
Precise Gaussian Blur 16
Precise Gaussian Blur 16
Precise Gaussian Blur 16.jpg (12.34 KiB) Viewed 2115 times
Gaussian Blur 16
Gaussian Blur 16
Gaussian Blur 16.jpg (9.34 KiB) Viewed 2114 times
Maciej Tomczak
Phototramp.com
tomczak
Posts: 1367
Joined: April 25th, 2009, 12:56 am
What is the make/model of your primary camera?: Fuji X-E2
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Re: Local Contrast Enhancement

Post by tomczak »

Two (semi-academic) questions re. Bilateral Sharpen:

1) Is sharpening done on each RBG channel separately, or on HSV-V?

2) Is there a way of 'softening' Sharpen Threshold?
Maciej Tomczak
Phototramp.com
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