Selective color-based blur
(actual version 0.3.0, development version - NONE)

is gimp plugin that blurs the color information (both hue and saturation) in image. The purpose is to blur luma noise and/or partition image to homogenous areas (with similar color). The next step should be saturating or selective modification of areas based on current colors. One of possible scenarios is saturation of poorly saturated images.

Alternatively you can use it for creating of cartoon like images.

For more info you can visit: http://code.google.com/p/selective-color-blur/wiki/Introduction

For some other info, to discuss and for windows packages visit: http://registry.gimp.org/node/25801

TO BE FOUND at: FILTERS -> BLUR -> COLOR SELECTIVE BLUR

The plugin is multithreaded (5 threads, can be changed in the source)

==HOW IT WORKS AND USE MINIGUIDE:==

The plugin works in iterations and with each iteration it tests n (n=radius) pixels in eight directions - up, right, down, left and diagonally between them. If color  distance of all n pixels to central pixel is below the treshold (in normalized RGB colorspace, i.e. brightness is ignored) then those pixels are considered for blurring. So final values are caclulaled as average from values from central pixel and average from up to 8 lines of pixels. (Perhaps some graphical explanation would be usefull here.
Sinca about 0.2.2 you can set up also brightness treshold, seems to be very usefull option as well.

User defines four basic parameters:
RADIUS - this is radius per single blurring, or this is length of line of pixels goind from central pixel in 4 directions. Please note that when your images is too fragmented, the higher radius might cause less blurring.
ITERATIONS - how many times the procedure described above is repeated. 
(I can say that RADIUS * ITERATIONS = overall radius of blurring)
COLOR TRESHOLD - should be obvious
VALUE (BRIGHTNESS) TRESHOLD - should be obvious as well just keep in mind that brightness is converted to values 0 - 1.

And there is a combobox with 3 options:
 "No change (blur the color only)"  - color is blurred but brightness is preserved. The results f.e. during tweaking of parameters are hard to see but this will save you some steps in workflow
 "Color Mask (fixed brightness)"   - creates "color mask" - intended as a upper layer to be put to "hue" mode above original layer (read ISSUES below). Or another option is to use "grain merge" mode.
 "Subordinated Blurring / Cartoon Mode";  - blurres also brightness, but according to color values. Maybe not badly usefull, but it gives some interesting results. 
EXPORT AS NEW LAYER (obvious as well)
DOUBLED SATURATION - this just doubles saturation, might be usefull sometimes

==INSTALLATION:==

On LINUX:
for user:
gimptool-2.0 --install colorblur.c
and for system-wide installation:
gimptool-2.0 --install-admin colorblur.c

For WINDOWS and others:
I'm not able to compile it for windows, but visit this page and search within the discussion: http://registry.gimp.org/node/25801


==ISSUES & SHORTCOMINGS ==

The main problem is with gimp's "color" mode (for layers). It just doesnt not behave as expected. So if using "color mask" option, put the newly created mask layer to hue mode. Alternatively, you can double the mask layer and one copy put into hue and the other into saturation mode. In fact, with this setup you will achieve the result that "color" mode is suppose to provide.

==CONTACT==

tiborb95 at gmail dot com, any feedback welcomed

Last update: 19. Nov 2011

