Is there any way to get the range of colors used in ImageMagick's -fuzz option? -

-

i'm trying hack image search uses color "distance," (or "tolerance", or "variance") similar what's done in imagemagick's -fuzz option: http://www.imagemagick.org/usage/color_basics/#fuzz_distance.

what i'm hoping a range or array of rgb values single initial pixel can use match against comparison points in database.

obviously what's happening -fuzz euclidean distance formula describing sphere in rgb cube, i'm not sure find mathematics or how use imagemagick (or other library) accomplish this.

thoughts?

as stated here in magemagick's forums, color b within fuzz range r of color a if euclidian distance lower r:

sqrt((b.r - a.r)^2 + (b.g - a.g)^2 + (b.b - a.b)^2) < r

r, g , b stand colors' respective red, blue , green values.

if don't have transparency, that's it. if need consider transparency, have multiply colors respective alpha channel value before using them in formula.

in 3-dimensional rgb color space, colors within fuzz range of color indeed form sphere (of radius r).

for checking agains points in database, can check formula if inside sphere.

regarding color ranges: since range of "fuzzy" (= within fuzz range :-) ) colors 1 dimension depends on position in other 2 dimensions, thing generate enclosing cube around fuzzy sphere. won't give right colors, use reject colors lie outside of cube. ranges cube are:

(a.r - r) <= b.r <= (a.r + r) (a.g - r) <= b.g <= (a.g + r) (a.b - r) <= b.b <= (a.b + r)

update:

here code reference calculation. looks bit more complicated, because has handle cmyk colors. rgb, reduces above-mentioned case.


Comments

Post a Comment

Popular posts from this blog

c# - SVN Error : "svnadmin: E205000: Too many arguments" -

-
i trying reposotries using c# code process svncommand = null; var psi = new processstartinfo("svnadmin"); psi.redirectstandardoutput = true; psi.redirectstandarderror = true; psi.useshellexecute = false; psi.arguments= @"dump c:\repositories\myrepo > c:\temp\myrepodumpfile.dump"; using (svncommand = process.start(psi)) { var myoutput = svncommand.standardoutput; var myerror = svncommand.standarderror; debug.write("output :" + environment.newline + environment.newline + myoutput.readtoend() + environment.newline + "error :" + environment.newline + environment.newline + myerror.readtoend()); svncommand.close(); } when use dump command commandline svnadmin dump c:\repositories\myrepo > c:\temp\myrepodumpfile.dump it works fine when try ...
Read more

c# - Copy ObservableCollection to another ObservableCollection -

-
how copy observablecollection item observablecollection without reference of first collection? here observablecollection item value changes affecting both collections. code private observablecollection<ratemodel> _allmetalrate = new observablecollection<ratemodel>(); private observablecollection<ratemodel> _metalrateondate = new observablecollection<ratemodel>(); public observablecollection<ratemodel> allmetalrate { { return this._allmetalrate; } set { this._allmetalrate = value; notifypropertychanged("metalrate"); } } public observablecollection<ratemodel> metalrateondate { { return this._metalrateondate; } set { this._metalrateondate = value; notifypropertychanged("metalrateondate"); } } foreach (var item in metalrateondate) allmetalrate.add(item); what causing , how can solve it? you need clone object referenced item before it's a...
Read more

All overlapping substrings matching a java regex -

-
is there api method returns (possibly overlapping) substrings match regular expression? for example, have text string: string t = 04/31 412-555-1235; , , have pattern: pattern p = new pattern("\\d\\d+"); matches strings of 2 or more characters. the matches are: 04, 31, 412, 555, 1235. how overlapping matches? i want code return: 04, 31, 41, 412, 12, 55, 555, 55, 12, 123, 1235, 23, 235, 35. theoretically should possible -- there obvious o(n^2) algorithm enumerates , checks substrings against pattern. edit rather enumerating substrings, safer use region(int start, int end) method in matcher . checking pattern against separate, extracted substring might change result of match (e.g. if there non-capturing group or word boundary check @ start/end of pattern). edit 2 actually, it's unclear whether region() expect zero-width matches. specification vague, , experiments yield disappointing results. for example: string line = "xx90xx"; strin...
Read more