adjustment

Exact Aligner

vtries — Fri, 02 Oct 2009 08:06:05 +0200

This script brings 2 pictures to an exact overlap.
The pictures must be in 2 different layers of the same image.
Get the layer 2 with 50% transparency. This makes both pictures visible in one projection.
You have to tell the script, which 2 points have to overlap. Therefore you stroke a path with a path tool in the image including 4 points. Point 1 will be aligned with point 3 and point 2 will be aligned with point 4.
The points build one path. So you can just click the 4 points consecutively.
More description is in the file.

Thanx
Volker Tries
(c) 2009

Maximize Local Contrast

Roy Johnson — Wed, 01 Jul 2009 18:36:27 +0200

FX-Foundry/Photo/Enhancement/Maximize Local Contrast... Like Stretch Contrast, but instead of using the minimum and maximum pixel values from the entire image, uses the minimum and maximum in the vicinity of a pixel to compute its new value. Takes a while to run, but really brings out textures. Result is a Grain Merge layer that adjusts values of the original image.

This filter operates on the visible image, not on a layer or selection.

Radius indicates how wide a pixel's influence is. If you choose too small a value, adjustment will be too localized and the image will look patchy. Larger values take a bit longer to run.

Threshold indicates how many neighboring gray values above and below a value can be treated as the same, in finding minimum and maximum values. Purely a speed trade-off. Using very low values will make it very slow. Too high values will cause visible "steps" in color values. The latest version does not include threshold, but the older version is still available.

"Feather Haloes" helps smooth out haloes around high-contrast areas.

"Keep Min and Max Layers" leaves the intermediate layers in the stack so you can look at them if you're interested.

Update (21 Jul 2009):

New algorithm that works right without any compromises for speed. No scaling, no threshold. It does take a bit of time on large images; 45 seconds for a 1500x2000 pixel image on a modern but not especially powerful PC. The full 8-megapixel image took about 3 minutes. Most of the time is spent on grow-selection, so don't be alarmed when the progress meter seems to hang up for a while. There are just two grows and two feathers to do.
If you want a speed compromise, I've added Scaledown factor, which will reduce the time spent in selection a lot, but will add some time for scaling the image. There's essentially no loss of quality. Recommended for especially large images.

Updates (13 Jul 2009):

SPEED! Mapping of Min and Max is done on scaled-down layers. Now even large images can be done in reasonable time.
Feather haloes feature for more reasonable results on high-contrast images and images with big flat areas
Layer mask keeps narrow-contrast areas under control

Updates (9 Jul 2009):

Fixed the bug that left strange artifacts in the image.
Changed radius to work as a % of image size (maximum dimension)
Increased feathering and added limits to min and max layers to control haloes around small, high-contrast features
Got rid of sample images. Will find better examples.

UnsharpMask2.0.12 (Windows binary -source code)

PhotoComiX — Mon, 16 Mar 2009 06:00:38 +0100

This plugin is not more maintained but still works very well On Gimp 2.6 and even 2.7
Was developed by Peter Heckert , Windows binary were provided by Michael Schumacher. but the original side is offline from years and all old links dead

i am mirroring both source code and binaries to avoid it can get lost and i repost here also in the hope that may found more users and a maintainer (as i said still works very well ,from gimp 2.0 till 2.7 a maintainer may help for the future )

About the most obvious question, what is the difference with standard unsharp mask that is simple,
what gimp USM offer is a only a subset of what this plugin may do.

gimp USM works ,basically by adding a blurred duplicate ,that as result create a white halo around contour's edges.

As example if you have a black arrow on dark grey BG, a more or less wide white halo around the arrow will made it much more visible and the image more sharp
But that easily lead to effect similar to overdone HDR and work better on the darker part of the image to reveal less dark details

Well USM2 may do that but also the contrary, sharpen by adding a dark halo
To use a similar example may sharpen a gray arrow on a white BG by creating a dark halo around arrow's contour

"Dark halo" sharpening on photos look often more natural then white at the most usual settings,
while pushing for dramatic setting is usually a more pleasant and artistic effect,
( we are used to accept black outlines as in draw,comics, illustration, so are more acceptable for our eyes then white outlines ..
Note that a thin but very intense white halo around contours edges is identical to white outlines, as a thin and very dark halo is identical to black outlines ..this is relevant for "artistic" or "creative" uses )

Interface may look too complex at first but just draw a ideal line under the 4th slider will solve

All what up is "BASIC" : on 4 sliders there 3 correspond exactly to that of the Gimp USM
"+" is to regulate the "white halo sharpening" ,"-" to regulate the "dark halo sharpening"
(NOTE: If both"+" and "-" are set to 0 then plugin do not sharpen but create a gaussian blur )

All what after that ideal line is "ADVANCED" ...default is fine in most cases anyway from there you may correct the gamma, or dose the intensity of the effect differently on shadows, middletones and highlights.

More accurate information are included in the zip.
#####################################################################
If someone may provide a better description is welcome , i am a user and not a developer and my English is quite approximate.

DOWNLOAD
http://photocomix-resources.deviantart.com/art/Lost-Found-Gimp-UnsharpMa...

Scale in steps

Loxley — Thu, 25 Sep 2008 07:50:39 +0200

About

"Scale in steps" resizes an image to the given dimensions in several steps to get a way sharper result compared to resizing in one step. The step size is given in percent and should range between seven and ten percent.

Samples

None of the sample images are sharpened. The original picture was 3000×2000.

baerm_s5.jpg: Stepsize: 5%
baerm_s.jpg: Stepsize: 10%
baerm_f.jpg: Traditional scaling

D-Dayed

tuxcomputers — Sat, 14 Jun 2008 10:36:31 +0200

D-Dayed is a script for The GIMP
Makes the image like the over saturated grainy war photos as evoked in the cinematography of films like Saving Private Ryan

Urban Acid

tuxcomputers — Sun, 08 Jun 2008 22:36:50 +0200

This script simulates the colour effect you get when you cross process a film.

Before:

After:

Relative color remap

larsrc — Tue, 03 Jun 2008 13:22:55 +0200

This plug-in changes colors in an image based on the HSV difference between two colors. This is particularly useful for applying color themes to existing images.
It avoids burning out high saturation and value at the expense of compression them somewhat when the difference goes towards higher saturation and value.
Current bugs/missing features include:
Undo does not work.
It can't be used on indexed images, even though it would frequently have enough colors.
It's slooow. Since it looks at only one pixel at a time, it should use some "pixel-iterator" that goes through the tiles in an optimal manner.
Selection only works in binary.
Grayscale support is untested and probably broken.
There is no preview.
Prevention of highlight burnout should be optional.

Saturation layer

Zigazou — Thu, 14 Feb 2008 12:08:57 +0100

This script allows you to extract and apply saturation to a layer. When you extract, it adds a new layer with the saturation values (in gray colors). You can then use curves, brightness/contrast or the dodge tool to correct saturation. When you are okay with the adjustements you can put back the saturation by applying it.

It installs itself in < script-fu >/Saturation.

Comments inside the script are in french.

Blue Sky & Clouds

Darla — Sat, 26 Jan 2008 09:42:42 +0100

To fix burned out or white skies by adding clouds and a blue sky gradient (using a threshold mask).

Guide to Using the Blue Sky & Clouds Script

Purple Fringe Fix

Darla — Wed, 23 Jan 2008 12:58:16 +0100

To reduce the effects of Purple Fringing or Chromatic Aberration in high contrast areas of an affected photograph.

Guide to Using the Purple Fringe Script