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Convert image to pencil sketch effect in android

how to convert photos and images (bitmaps) to pencil sketches (as shown below)? I cannot find any good sources on how to do this.

I want to make an Android app that can programmatically "convert" a JPEG photo to pencil sketch images.

Could you please help me with this. sketch effect

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3 answers


One way is to write your own filters using the information provided in this post



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Read the image first

g = Convert-To-Gray-Scale(s)

i = Invert-Colors(g)

b = Apply-Gaussian-Blur(i)

result = Color-Dodge-Blend-Merge(b,g)


https://github.com/finebyte/android-jhlabs/issues/2

Also see https://github.com/geraintluff/canvas-sketch

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'public static Bitmap toGrayscale(Bitmap src) {
        final double GS_RED = 0.299;
        final double GS_GREEN = 0.587;
        final double GS_BLUE = 0.114;
        Bitmap bmOut = Bitmap.createBitmap(src.getWidth(), src.getHeight(), src.getConfig());
        int A, R, G, B;
        int pixel;
        int width = src.getWidth();
        int height = src.getHeight();
        for (int x = 0; x < width; ++x) {
            for (int y = 0; y < height; ++y) {
                // get one pixel color
                pixel = src.getPixel(x, y);
                A = Color.alpha(pixel);
                R = Color.red(pixel);
                G = Color.green(pixel);
                B = Color.blue(pixel);
                R = G = B = (int) (GS_RED * R + GS_GREEN * G + GS_BLUE * B);
                bmOut.setPixel(x, y, Color.argb(A, R, G, B));
            }
        }
        return bmOut;
    }
    public static Bitmap createInvertedBitmap(Bitmap src) {
        Bitmap bmOut = Bitmap.createBitmap(src.getWidth(), src.getHeight(), src.getConfig());
        int A, R, G, B;
        int pixelColor;
        int height = src.getHeight();
        int width = src.getWidth();
        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                pixelColor = src.getPixel(x, y);
                A = Color.alpha(pixelColor);
                R = 255 - Color.red(pixelColor);
                G = 255 - Color.green(pixelColor);
                B = 255 - Color.blue(pixelColor);
                bmOut.setPixel(x, y, Color.argb(A, R, G, B));
            }
        }
        return bmOut;
    }
    public Bitmap ColorDodgeBlend(Bitmap source, Bitmap layer) {
        Bitmap base = source.copy(Bitmap.Config.ARGB_8888, true);
        Bitmap blend = layer.copy(Bitmap.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;
    }
    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)))));
    }'
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