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Topic: pixels[] doubt (Read 3057 times) |
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Dimitre
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pixels[] doubt
« on: Nov 14th, 2002, 8:03pm » |
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Hello! I have a doubt about mixing color numbers.
I am working with the built-in pixels[] array and another (pixels2[]) that I created.
Do you a way to "add" one to another, creating Multiply effect?
pixels[] Multiply pixels2[]
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fry
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Re: pixels[] doubt
« Reply #1 on: Nov 15th, 2002, 1:24am » |
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there isn't a way to do this for free.. you'll just have to iterate over the pixel array, unpack the r/g/b components with some bit-shifting, then add, then re-pack.
and please follor up if you 1) don't know what i mean and need an example or 2) write the example for yourself, so you can share it with the rest of us.
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Dimitre
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Re: pixels[] doubt
« Reply #2 on: Nov 18th, 2002, 9:37pm » |
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Thanks fry. This worked fine for me:
Code:red = pixels2[index] >> 16;
green = (pixels2[index] - (red << 16)) >> 8;
blue = pixels2[index] - (green << 8) - (red << 16); |
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I also found this blending modes reference, very interesting to play with it: http://pegtop.net/delphi/blendmodes/
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| « Last Edit: Nov 18th, 2002, 10:19pm by Dimitre » |
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fry
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Re: pixels[] doubt
« Reply #3 on: Nov 18th, 2002, 11:16pm » |
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that's a great reference. thanks for posting the link.
the following code may be more straightforward/correct (faster in the case of the blue component) for unpacking numbers.
Code:red = (pixels2[index] >> 16) & 0xff;
green = (pixels2[index] >> 8) & 0xff;
blue = pixels2[index] & 0xff;
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some explanation, for the folks that might not know about this stuff...
Code:the bits in a pixel look like this:
AAAAAAAARRRRRRRRGGGGGGGGBBBBBBBB
(where A is alpha, R is red.. etc)
so when you shift the red 16 to the right (>> 16 above) then the pixel looks like this:
0000000000000000AAAAAAAARRRRRRRR
and you use the & 0xff to hack off the other bits, and just save the 8 bits that you need for the color component itself. 0xff is 8 bits, all set to 1. so:
0000000000000000AAAAAAAARRRRRRRR
"and"
00000000000000000000000011111111
will be
000000000000000000000000RRRRRRRR
because the "and" operation only lets through the bits that are set in both numbers.
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(sorry for the tiny monospaced font, but the text makes more sense in mono so the letters line up)
[ ANOTHER METHOD, for the beginners, or those more obsessed with clarity than speed ]
for those who don't need the speed of using ints and unpacking things like this, you can use something like:
Code:color pixel = getPixel(4, 5);
float r = red(pixel);
float g = green(pixel);
float b = blue(pixel);
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the numbers for r, g, b will be scaled to the current colorMode. i.e. if you're using colorMode(RGB, 1), all the numbers will be between 0..1. useful for sane, simpler coding, but a bit slower because of the extra work to turn the colors into something more like the current color mode.
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| « Last Edit: Nov 18th, 2002, 11:18pm by fry » |
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Dimitre
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Re: pixels[] doubt
« Reply #4 on: Nov 19th, 2002, 5:45pm » |
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Thanks fry! very fine the "& 0xff" use.
I updated my code and put one multiply mode experiment at http://dmtr.org/generative.
Soon I will post more.
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| « Last Edit: May 18th, 2004, 10:17pm by Dimitre » |
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hurlbot
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Re: pixels[] doubt
« Reply #5 on: Jan 23rd, 2003, 7:52am » |
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I get this error with all the processing applets on your page:
Connecting http://dimitre.locaweb.com.br/jars/sereia.jar with no proxy
Downloading http://dimitre.locaweb.com.br/jars/sereia.jar to cache
java.lang.IllegalArgumentException
at java.util.zip.ZipInputStream.getUTF8String(Unknown Source)
at java.util.zip.ZipInputStream.readLOC(Unknown Source)
at java.util.zip.ZipInputStream.getNextEntry(Unknown Source)
at sun.plugin.cache.CachedJarLoader.decompress(Unknown Source)
at sun.plugin.cache.CachedJarLoader.access$500(Unknown Source)
at sun.plugin.cache.CachedJarLoader$5.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.plugin.cache.Cache.privileged(Unknown Source)
at sun.plugin.cache.CachedJarLoader.download(Unknown Source)
at sun.plugin.cache.CachedJarLoader.load(Unknown Source)
at sun.plugin.cache.JarCache.get(Unknown Source)
at sun.plugin.net.protocol.jar.CachedJarURLConnection.connect(Unknown Source)
at sun.plugin.net.protocol.jar.CachedJarURLConnection.getJarFile(Unknown Source)
at sun.misc.URLClassPath$JarLoader.getJarFile(Unknown Source)
at sun.misc.URLClassPath$JarLoader.<init>(Unknown Source)
at sun.misc.URLClassPath$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.misc.URLClassPath.getLoader(Unknown Source)
at sun.misc.URLClassPath.getLoader(Unknown Source)
at sun.misc.URLClassPath.getResource(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at sun.applet.AppletClassLoader.findClass(Unknown Source)
at sun.plugin.security.PluginClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadCode(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.plugin.AppletViewer.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception: java.lang.IllegalArgumentException
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benelek
 
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Re: pixels[] doubt
« Reply #6 on: Jan 23rd, 2003, 3:16pm » |
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i also get this error with all the p5 applets on ur page.
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Dimitre
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Re: pixels[] doubt
« Reply #7 on: Feb 3rd, 2003, 8:41pm » |
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Thanks Guys!
I will check this.
I decompressed all the jar files, for proce55ing cache reutilization, but maybe this only worked in Microsoft VM.
Do you use Microsoft Virtual Machine, or Java Plugin?
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Glen Murphy
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Re: pixels[] doubt
« Reply #8 on: Feb 3rd, 2003, 11:51pm » |
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I use the Java plugin, and they weren't working. ARr.
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Dimitre
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Re: pixels[] doubt
« Reply #9 on: Feb 19th, 2003, 9:30pm » |
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thanks. Now it is fixed
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