computer vision - Not sure what this 'histogram code' is doing in MATLAB -



computer vision - Not sure what this 'histogram code' is doing in MATLAB -

i have next code given me, not sure @ logic here is. idea, believe, histogram/quantize data. here code:

the input:

x = 180.*rand(1,1000); %1000 points 0 180 degrees. binwidth = 20; %i want binwidth 20 degrees.

the main function:

% ------------------------------------------------------------------------- % compute closest bin center x1 less or equal x % ------------------------------------------------------------------------- function [x1, b1] = computelowerhistbin(x, binwidth) % bin index bin = floor(x./binwidth - 0.5); % bin center x1 x1 = binwidth * (bin + 0.5); % add together 2 1-based indexing b1 = bin + 2; end

finally, final 'quantized' data:

w = 1 - (x - x1)./binwidth

here not get: not understand - @ - why x1 computed way is, , why/how w computed way is. in fact, of things, w confuses me most. literally cannot understand logic here, or intended. appreciate detailed elucidation of logic. thanks.

he binning lb <= x < up , splitting interval [0,180] in [-10,10), [10, 30), [30,40) ..., [150,170), [170,190).

suppose x = 180, then:

bin = floor(180/20-0.5) = floor(9-0.5) = floor(8.5) = 8;

while if x = 0:

bin = floor(`0/20-0.5) = floor(-0.5) = floor(-1) = -1;

which respectively translate x1 = 20 * (8+0.5) = 170 , x1 = -10 seems function suggests lowerhistbin().

in end, w measures how far point x corresponding lower bin x1. notice w in (0,1], w beingness 1 when x = x1 , approaching 0 when x -> x1+binwidth. so, if x approaches 170, w approach 1 - (170-150)/20 = 0.

matlab computer-vision histogram matlab-cvst quantization

Comments

Post a Comment

Popular posts from this blog

java Multi query from Mysql using netbeans -

java Multi query from Mysql using netbeans - i have java code retrieve info mysql appropriate code in netbeans.the code below. want multi query such illustration finding total number of products , on.could help me please. in advance import java.sql.*; public class javamysqlselectexample { public static void main(string[] args) { seek { string mydriver = "com.mysql.jdbc.driver"; string myurl = "jdbc:mysql://localhost/sample"; class.forname(mydriver); connection conn = drivermanager.getconnection(myurl, "root", "mypasscode1"); string query = "select * products"; statement st = conn.createstatement(); resultset rs = st.executequery(query); while (rs.next()==true) { int code = rs.getint("code"); string productname = rs.getstring("product_name"); string producttype = rs.getstring("product_type"); system.out.format(" %d, %s, %s\n", code, pr
Read more

c# - DotNetZip fails with "stream does not support seek operations" -

c# - DotNetZip fails with "stream does not support seek operations" - i using dotnetzip in c# unzip stream follows: public static void unzipfromstream(stream stream, string outdir) { //omit seek grab block using (zipfile zip = zipfile.read(stream)){ foreach (zipentry e in zip){ e.extract(outdir, extractexistingfileaction.overwritesilently); } } } stream obtained using webclient client = new webclient(); stream fs = client.openread(url); however, got next exception exception during extracting zip stream system.notsupportedexception: stream not back upwards seek operations. @ system.net.connectstream.get_position() @ ionic.zip.zipfile.read(stream zipstream, textwriter statusmessagewriter, encoding encoding, eventhandler`1 readprogress) on server side(asp.net mvc 4), returning filepathresult or filestreamresult both caused exception. should obtain stream differently on client side? or how create server homec
Read more

c++ - StartServiceCtrlDispatcher don't can access 1063 error -

c++ - StartServiceCtrlDispatcher don't can access 1063 error - i write on c++ service , have error, , don't can fixed it. my service main function int main (int argc, tchar *argv[]) {dword f; for(int i=0;i<113;i++) f = getlasterror(); servicepath = lptstr(argv[0]); outputdebugstring(_t("my sample service: main: entry")); //installservice(); service_table_entry servicetable[] = { {service_name, (lpservice_main_function) servicemain}, {null, null} }; // startservice(); if(!startservicectrldispatcher(servicetable)) { f = getlasterror(); //addlogmessage("error: startservicectrldispatcher"); } else if( memcmp(argv[argc-1],"install",7)) { installservice(); } else if( memcmp(argv[argc-1],"remove",6)) { removeservice(); } else if( memcmp(argv[argc-1],"start",5)) { startservice(); } else if( memcmp(argv[argc-1],"stop",4))
Read more