Google| Subject | Re: Lenses and sharpening |
| From | Eric Stevens |
| Date | 09/20/2014 02:54 (09/20/2014 12:54) |
| Message-ID | <69jp1adfm872bdd91ot20kgl7lfavflok8@4ax.com> |
| Client | |
| Newsgroups | rec.photo.digital |
| Follows | Sandman |
| Followups | Floyd L. Davidson (37m) Sandman (10h & 14m) > Eric Stevens |
On 19 Sep 2014 07:02:13 GMT, Sandman <mr@sandman.net>wrote:
SandmanUnfortunately he knows too much, compared with the rest of us. I did wonder when he threw in that JPEG conversion but I finally he concluded that he was trying to make a point.
In article <na4n1a9tqb8cr0bcsqju244pdvkiui43g8@4ax.com>, Eric Stevens wrote:Eric StevensCorrection:
He never claimed that the JPG can be reversed. As I have already written, he said that the original image can be recovered after sharpening by HPS even after the image has been saved as a JPG.He never claimed that the JPG can be reversed.Sandman
Correction:
He did.Eric StevensSandman
As I have already written, he said that the sharpening of the original image can be recovered after sharpening by HPS even after the image has been saved as a JPG.
Which requires that the JPG compression is reversed as well. Floyd didn't realize this because he doesn't know how these things work.
The settings for HPS is a set of numbers. The settings for Gaussian blur is another set of numbers. Applying HPS or GB to an image is basically the same process and what you get depends upon the numbers you feed to it.
What I think Floyd was saying that even with the loss of information and image data inherent in a JPEG conversion you can restore the original sharpening by changing the numbers you apply to the image saved as a JPEG.
Image 1 --->Apply HPS settings --->Save as JPEG --->Reverse HPS
gets you to the same place as Image 1 --->Save as JPEG
You can't do that if the original sharpening was USM as it is not fully reversible. --
Regards,
Eric Stevens
09/13/2014-
