Java - Red, Green, Blue to getRGB

Question

By calling getRGB(int x, int y) with a BufferedImage object, one gets a single, negative number.

How can I convert three different values (a red, a green, and a blue) into this single, negative number?

btw. every BufferedImage contains an array that holds all the pixels. If the BufferedImage is of type TYPE_INT_RGB that array will be an int array. So if you want to do a lot of pixel manipulation you can speed up your program by writing directly to that array. You can get it with int[] pixels = ((DataBufferInt)image.getRaster().getDataBuffer()).getData() — Tesseract, Dec 02 '12 at 01:56
Possible duplicate of [Java BufferedImage getting red, green and blue individually](https://stackoverflow.com/questions/2615522/java-bufferedimage-getting-red-green-and-blue-individually) — Michu93, Jan 25 '19 at 12:47
@Michu93 This question asks the reverse of that, so this isn't a duplicate — Mark Rotteveel, Jan 25 '19 at 16:10

score 10 · Accepted Answer · answered Dec 01 '12 at 21:41

10

Using the Color class:

new Color(r, g, b).getRGB()

answered Dec 01 '12 at 21:41

JB Nizet

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This will use more resources than is necessary. – FThompson Dec 01 '12 at 21:42
@Vulcan: agreed. But Color is open-source, so the OP could "steal" the code. – JB Nizet Dec 01 '12 at 21:45
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@JBNizet `int rgb = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0);` – FThompson Dec 01 '12 at 22:11

score 3 · Answer 2 · answered Dec 01 '12 at 21:41

BufferedImage ends up delegating to java.awt.image.ColorModel which uses the following code:

public int getRGB(Object inData) {
    return (getAlpha(inData) << 24)
        | (getRed(inData) << 16)
        | (getGreen(inData) << 8)
        | (getBlue(inData) << 0);
}

Modifying this to suit your needs is a trivial exercise.

score -1 · Answer 3 · edited May 23 '17 at 11:58

-1

JB Nizet's answer is great, but it can be really slow when creating new objects of type 'Color' thousands of times. The simplest way would be:

int rgb = (red << 16 | green << 8 | blue)

As answered by ByteBit

edited May 23 '17 at 11:58

Community

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answered Apr 16 '15 at 11:37

Zar E Ahmer

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Did you steal this? lol http://stackoverflow.com/questions/24594046/converting-red-green-and-blue-to-rgb/24596140#24596140 – ByteBit Aug 01 '15 at 16:46
I apologize for not giving reference to your answer.Now see edit – Zar E Ahmer Aug 01 '15 at 16:53

Java - Red, Green, Blue to getRGB

3 Answers3

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