Question

I have two bitmaps topBitmap and bottomBitmap and I need to blend the two bitmaps using color dodge in android. I could not find color dodge in PorterDuffXfermode. Is there any way to do it with ot without the use of a Canvas?

Kindly let me know how to blend two bitmaps using color dodge mode in android.Thanks in advance.

Answer 1

Hi I found this method from somewhere in SO post. This method takes two image and create one image using color dodge

public Bitmap ColorDodgeBlend(Bitmap source, Bitmap layer) {
            Bitmap base = source.copy(Config.ARGB_8888, true);
            Bitmap blend = layer.copy(Config.ARGB_8888, false);

            IntBuffer buffBase = IntBuffer.allocate(base.getWidth() * base.getHeight());
            base.copyPixelsToBuffer(buffBase);
            buffBase.rewind();

            IntBuffer buffBlend = IntBuffer.allocate(blend.getWidth() * blend.getHeight());
            blend.copyPixelsToBuffer(buffBlend);
            buffBlend.rewind();

            IntBuffer buffOut = IntBuffer.allocate(base.getWidth() * base.getHeight());
            buffOut.rewind();

            while (buffOut.position() < buffOut.limit()) {

                int filterInt = buffBlend.get();
                int srcInt = buffBase.get();

                int redValueFilter = Color.red(filterInt);
                int greenValueFilter = Color.green(filterInt);
                int blueValueFilter = Color.blue(filterInt);

                int redValueSrc = Color.red(srcInt);
                int greenValueSrc = Color.green(srcInt);
                int blueValueSrc = Color.blue(srcInt);

                int redValueFinal = colordodge(redValueFilter, redValueSrc);
                int greenValueFinal = colordodge(greenValueFilter, greenValueSrc);
                int blueValueFinal = colordodge(blueValueFilter, blueValueSrc);


                int pixel = Color.argb(255, redValueFinal, greenValueFinal, blueValueFinal);


                buffOut.put(pixel);
            }

            buffOut.rewind();

            base.copyPixelsFromBuffer(buffOut);
            blend.recycle();

            return base;
        }

here is the method do get the color dodge for pixel to get the effect

private int colordodge(int in1, int in2) {
            float image = (float)in2;
            float mask = (float)in1;
            return ((int) ((image == 255) ? image:Math.min(255, (((long)mask << 8 ) / (255 - image)))));
        }

I am trying to create sketch image of original photo, using this method I am able to create cartoonifying the image in color full format but I need in black and white pencil sketch format. If you have any idea then please share it.

hope this methods are useful to you