How do I select a region by color in a Bitmap?

Question

Please suggest an efficient way to select a region by color in a bitmap. Then replace this selected region-color to your desired color.

For example, If an image contains four colors say red, green, yellow, orange. Now suppose user clicked on yellow color, so select yellow colored region surrounding to the clicked position and now replace the yellow color to blue.

Hope, I explained the question properly. Kindly comment if need any more clarification.

As per my knowledge, bitmap is a memory consuming task and results into out of memory error.

Please share any link or sample code that will help me to implement this feature to my app.

Hi i'm looking for the same thing from few days. Did you find any solution on this is yes please let me know. — praveen2034, Nov 22 '18 at 07:55

score 0 · Answer 1 · answered Oct 31 '15 at 14:49

0

If you want to get the color of every pixel you could do it this way:

for(int i=0;i<bitmap.getWidth();i++){
for(int j=0;j<bitmap.getHeigth();j++){
    int pixel = bitmap.getPixel(i,j);
    if(pixel == Color.RED){
        //Do something
    }
}
}

So what you could do is first find the color of the pixel tapped by the user and then use the above technique to find the pixels of that particular color.

You can use the following to get the color code of the pixel tapped :

int ColorCode = imageView.getDrawingCache().getPixel(x, y);

Here x,y are the coordinates. You can refer this link for additional info - link

And don't forget to scale down the bitmap before loading it into memory to prevent OutOfMemory issues. You can refer android documentation to find how to do that. Handling large bitmaps

answered Oct 31 '15 at 14:49

Akash Singh

748
1
6
14

Thanks for a quick response. I tried with this approach. But, in case of heavy size images or hd images, it is giving me out of memory error. – user320676 Oct 31 '15 at 14:52
@user320676 feel free to accept the answer if it helped you. – Akash Singh Oct 31 '15 at 14:53
You can add this in your manifest to support large images. android:largeHeap="true" – priyankvex Oct 31 '15 at 15:47

score 0 · Answer 2 · edited Nov 02 '15 at 20:38

0

After spending a lot of time I got a useful link to do this work. It's called Kids Palette and here I'm sharing the link of source on GitHub.

edited Nov 02 '15 at 20:38

Joaquin Iurchuk

5,499
2
48
64

answered Nov 02 '15 at 20:33

user320676

394
2
19

score 0 · Answer 3 · answered Nov 02 '15 at 20:39

0

What about using Palette API?

Look the article [Extracting Colors to a Palette with Android]Lollipop(https://www.bignerdranch.com/blog/extracting-colors-to-a-palette-with-android-lollipop/)
Also read the official documentation about this tool

answered Nov 02 '15 at 20:39

Joaquin Iurchuk

5,499
2
48
64

How do I select a region by color in a Bitmap?

3 Answers3

Linked