Hi.
The german computer-magazine c't (No. 22/1999) described a cool method
to sharpen images including a Photoshop-action.
I converted it to a Script - it is attached.
Basically unsharp edges will get squeezed together, so that the edge
will get sharper (by edge-detecting, bluring, bump-mapping two times
for X- and Y-direction and displacing)
It works quite cool.
Bye,
Simon
--
Simon.Budig@xxxxxxxxxxx http://www.home.unix-ag.org/simon/
;;; warp-sharp.scm
;;; Date: <1999/10/30 0:50 simon@xxxxxxxx>
;;; Author: Simon Budig <simon@xxxxxxxx>
;;; Version 1.0
;;; This implements a method to sharpen images described by Joern Loviscach
;;; in the german computer-magazine c't, 22/1999.
;;; Basically it "squeezes" unsharp edges. This method is a simplified
;;; Version of an algorithm by Nur Arad and Craig Gotsman:
;;; "Enhancement by Image-Dependent Warping", IEEE Transactions on
;;; Image Processing, Vol. 8, No. 8, S. 1063
(define (script-fu-warp-sharp img drw edge-strength blur-strength bump-depth displace-amount)
(let* ((drawable-width (car (gimp-drawable-width drw)))
(drawable-height (car (gimp-drawable-height drw)))
(drawable-type (car (gimp-drawable-type drw)))
(old-selection 0)
; layer for detecting edges
(edge-layer (car (gimp-layer-copy drw 0)))
; layer for x-displace information
(x-displace-layer (car (gimp-layer-new img drawable-width
drawable-height drawable-type "Displace X" 100 0)))
; layer for x-displace information
(y-displace-layer (car (gimp-layer-new img drawable-width
drawable-height drawable-type "Displace Y" 100 0)))
(selection-info (gimp-selection-bounds img))
(has-selection (car selection-info))
(bump-xoff 0)
(bump-yoff 0)
)
(gimp-undo-push-group-start img)
(if has-selection (begin
; If there is a selection don't render too much.
(set! old-selection
(car (gimp-channel-copy (car (gimp-image-get-selection img)))))
(gimp-selection-grow img (+ blur-strength bump-depth displace-amount))
(set! selection-info (gimp-selection-bounds img))
(set! bump-xoff (cadr selection-info))
(set! bump-yoff (caddr selection-info))
))
; set up the layers
(gimp-drawable-fill x-displace-layer 2)
(gimp-drawable-fill y-displace-layer 2)
(gimp-image-add-layer img edge-layer -1)
(gimp-image-add-layer img y-displace-layer -1)
(gimp-image-add-layer img x-displace-layer -1)
; detect the edges and blur the layer a little bit
(plug-in-edge 1 img edge-layer edge-strength 1)
(if (>= blur-strength 1)
(plug-in-gauss-iir 1 img edge-layer blur-strength 1 1))
; create the displacement-maps by bump-mapping the edges.
; elevation=30: areas without edges will get a 50 % gray.
(plug-in-bump-map 1 img x-displace-layer edge-layer 0 30
bump-depth bump-xoff bump-yoff 0 0 0 0 0)
(plug-in-bump-map 1 img y-displace-layer edge-layer 270 30
bump-depth bump-xoff bump-yoff 0 0 0 0 0)
; restore the old selection
(if has-selection (begin
(gimp-selection-load old-selection)
(gimp-channel-delete old-selection)
))
; finally displace the image.
(plug-in-displace 1 img drw displace-amount displace-amount 1 1
x-displace-layer y-displace-layer 1)
; clean up...
(gimp-image-remove-layer img edge-layer)
(gimp-image-remove-layer img x-displace-layer)
(gimp-image-remove-layer img y-displace-layer)
(gimp-undo-push-group-end img)
(gimp-displays-flush)))
(script-fu-register
"script-fu-warp-sharp"
"<Image>/Script-Fu/Alchemy/Warp Sharp"
"Sharpen the current drawable by squeezing unsharp edges. Algorithm described by Joern Loviscach in c't 22/1999, p 236."
"Simon Budig <simon@xxxxxxxx>"
"Simon Budig"
"30. 10. 1999"
"RGB RGBA GRAY GRAYA"
SF-IMAGE "Image" 0
SF-DRAWABLE "Drawable" 0
SF-ADJUSTMENT "Edge detection" '(7 1 10 0.1 1 1 0)
SF-ADJUSTMENT "Blur radius" '(3 0 10 0.1 1 1 0)
SF-ADJUSTMENT "Bump depth" '(2 1 10 1 1 0 0)
SF-ADJUSTMENT "Displace intensity" '(2.5 0.1 10 0.1 0.5 1 0)
)
