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Author Topic: Capture sharpening - how much? and when?  (Read 1399 times)

Hening Bettermann

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Re: Capture sharpening - how much? and when?
« Reply #20 on: April 16, 2019, 03:42:51 pm »



Hi all!
@ JaapD
My Raw converter is Raw Therapee. Its automatic (lateral) CA correction saved an image for me which I had given up, and it has a great (manual) correction for longitudinal CA. - I was not aware of C1's automatic correction of diffraction. I think I understood that C1 has a somewhat peculiar color management, even though I don't know the details. And since RT is both very good and free, I'm not so much thinking of trying a new raw converter for the time being. Thanks for the tip though!

@Bart
Yes I understand that the Nearest Neighbour was meant just for viewing. I don't scale in RT, so there should be no danger.

> Smart software can convert from a gamma adjusted space back to linear gamma, perform the deconvolution, and return to the initial gamma. That does assume proper care in the math in order to avoid cumulation of rounding errors.

The question for me is 'How can I achieve that?' RT's working space is ProPhoto. There are other choices, but I don't think any of them has linear gamma; sure is only that their gamut is smaller than ProPhotos. - Is C1 the smart software you mention?

Bart_van_der_Wolf

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Re: Capture sharpening - how much? and when?
« Reply #21 on: April 16, 2019, 04:05:18 pm »

@Bart
Yes I understand that the Nearest Neighbour was meant just for viewing. I don't scale in RT, so there should be no danger.

Good, just wanted to make sure.

Quote
> Smart software can convert from a gamma adjusted space back to linear gamma, perform the deconvolution, and return to the initial gamma. That does assume proper care in the math in order to avoid cumulation of rounding errors.

The question for me is 'How can I achieve that?' RT's working space is ProPhoto.

We can't know what's going on under the hood, but I suspect that FocusMagic is doing the right thing. The RL sharpening might do something similar, don't know. One could study the open code of the latter, but I don't have the time for that.

In some Astrophotography oriented software, one does it "by hand", change the encoding mode to floating-point numbers, change the gamma to linear, deconvolve channel by channel, change gamma back, change the mode to 16-bit/ch. But that's a lot of work unless one makes a script for that.

Cheers,
Bart
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Bart_van_der_Wolf

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Re: Capture sharpening - how much? and when?
« Reply #22 on: April 16, 2019, 04:43:30 pm »

Hi, hope you don't mind, but I ran 'earlybird's original JPEG image through Sharpen AI, in Stabilize mode. Maybe there was turbulent hot air or something, but that mode helped better than an attempt to adjust for Defocus or just simple Sharpen the image.

Of course, the already sharp text and rectangle are now showing artifacts.

Cheers,
Bart
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earlybird

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Re: Capture sharpening - how much? and when?
« Reply #23 on: April 16, 2019, 05:14:04 pm »

Th AI results look good to my eyes.
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earlybird

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Re: Capture sharpening - how much? and when?
« Reply #24 on: April 16, 2019, 08:20:47 pm »

I used the original 16bit .psd to make three comparisons with Sharpen AI.

I think I am partial to the "sharpen" mode.

I have attached 3 samples that were upscaled 400% with nearest neighbor.

 FWIW, the 400% zooms with nearest neighbor upscale are useful if you want to pixel peep immediately. It saves the time of downloading and zooming with the picture viewer of your choice.

 The original "full size" example shown earlier was a 800x800 100% scale crop of a larger out take image made this past Saturday morning. The subject in the crop is a sandstone cliff with sunrise light cast upon it. The still air was about 50*F. The camera was positioned on a small rise, so the line of sight was far above the surface of the intervening terrain. In other words the air had relatively good seeing characteristics. The distance from the vantage point to the subject was approximately 1.46 miles (as measured on Google Earth) The lens was a 100-400mm zoom set at 164mm f8.0. The focal point was about 1900' away, so the portion of the subject shown in the 400% crop may be thought to be "reasonably well focused" as it is within the range of the hyperfocal distance for the lens and circumstance.

 Nevertheless, I was eager to apply some sharpening to the pictures made that morning to make the results as crisp and clean as I may be able.

 

 
« Last Edit: April 16, 2019, 10:23:59 pm by earlybird »
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JaapD

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Re: Capture sharpening - how much? and when?
« Reply #25 on: April 17, 2019, 01:00:35 am »

Hi Earlybird, thanks for sharing these examples!

My observations:
•   I see severe artifacts with ‘Sharpen’, including ghost images. Same as with my own images. For me absolutely a NOGO.
•   The ‘Focus’ seems over the top to me with respect to the halo’s. Possibly due to too 'strong' settings.
•   The 'Sharpen' is the way I like it, no halo’s, no artifacts.

Regards,
Jaap.
« Last Edit: April 17, 2019, 12:41:30 pm by JaapD »
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Arlen

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Re: Capture sharpening - how much? and when?
« Reply #26 on: April 17, 2019, 10:21:55 am »


 FWIW, the 400% zooms with nearest neighbor upscale are useful if you want to pixel peep immediately. It saves the time of downloading and zooming with the picture viewer of your choice.


How do you set zoom in Photoshop to use nearest neighbor upscaling?
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earlybird

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Re: Capture sharpening - how much? and when?
« Reply #27 on: April 17, 2019, 10:32:38 am »

I believe, as has been suggested previously in this thread, that Photoshop's "zoom +" function uses nearest neighbor by default so that you may zoom in and see a representation of the actual pixels in your 100% scale raster image.

The quote you have referenced describes an equivalence to a 400% zoom as realized with an upscale process using the "Image Size" dialog.

In other words, the upscaling was meant to mimic Photoshop's zoom effect.

« Last Edit: April 17, 2019, 10:38:49 am by earlybird »
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Arlen

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Re: Capture sharpening - how much? and when?
« Reply #28 on: April 17, 2019, 10:50:23 am »

OK, thanks. I knew you can do it by changing actual pixel dimensions in the Image Size dialog, but I thought you were saying that you could set the Zoom Tool to nearest neighbor, and I could not see how to do that.
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