![](public_html/YaBBImages/1pix.gif) |
Author |
Topic: how many colors in an image? (Read 431 times) |
|
lunetta
![72004752](http://web.icq.com/whitepages/online?icq=72004752&img=5)
![Email](public_html/YaBBImages/email.gif)
|
how many colors in an image?
« on: Dec 17th, 2004, 11:16am » |
|
Hello all I need some suggestion, advice or idea: I need to develop a piece of code that with the input of a image, it outputs an object array, each object having 2 properties: a unique color value, and its incidence. So, my main challenge so far is: How can I count how many unique colors I have in an image? I'm really grateful for any light in the shadow void of algorithms and data structures inside lunetta's mind.
|
« Last Edit: Dec 17th, 2004, 11:32am by lunetta » |
|
|
|
|
toxi
|
Re: how many colors in an image?
« Reply #2 on: Dec 17th, 2004, 3:19pm » |
|
here's one i made earlier/ages ago... should do pretty muc what you want. an Hashtable is an easy-to-use data structure for those type of problems: Code:BImage img; Hashtable uniqueCols; void setup() { size(200,200); img=loadImage("logo.gif"); // find & count occurance of unique colours uniqueCols=countUniqueColours(img); // get all colour names (RGB hexvalue) Enumeration colNames=uniqueCols.keys(); // compute contribution for each colour while(colNames.hasMoreElements()) { String currCol=(String)colNames.nextElement(); int currColCount=((IntCounter)uniqueCols.get(currCol)).getValue(); // display result print(currCol+": "); print(nf(currColCount*100.0/img.pixels.length,1,1)); println("% ("+currColCount+" pixels)"); } //display image image(img,0,0); } public Hashtable countUniqueColours(BImage img) { Hashtable index=new Hashtable(); for(int i=0; i<img.pixels.length; i++) { // use hex value of colour as hash code (unique ID) String col=Integer.toHexString(img.pixels[i]&0xffffff); if (!index.containsKey(col)) { // create new entry, if new colour index.put(col,new IntCounter(1)); } else { // or increase count for existing colour IntCounter counter=(IntCounter)index.get(col); counter.increment(); } } return index; } // counter/helper class // used by countUniqueColours() method class IntCounter { int value; IntCounter(int i) { value=i; } void increment() { value++; } int getValue() { return value; } } |
|
|
« Last Edit: Dec 17th, 2004, 3:23pm by toxi » |
|
http://toxi.co.uk/
|
|
|
lunetta
![72004752](http://web.icq.com/whitepages/online?icq=72004752&img=5)
![Email](public_html/YaBBImages/email.gif)
|
Re: how many colors in an image?
« Reply #3 on: Dec 17th, 2004, 6:16pm » |
|
thanks, I'll study both programs. I coded a counter last night, and 8 hours laters processing was still counting a 50x50 pixels image. That's slooooooooooow (It worked for a 10x10). So I guess my approach wasn't very good. Imagine a 1280x1024... thanks again for the feedback
|
|
|
|
|