How to Apply Color LUT to bitmap images for filter effects in android?

Question

here i have a question on LUTs in android.

my question is, i have 4X4 LUTs, Using these LUTs apply filter effect for bitmap image in android. Below is my sample LUT

Answer 1

This is how you would process an image with RenderScript's ScriptIntrinsic3DLUT

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsic3DLUT;
import android.renderscript.Type;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {
    ImageView imageView1;
    RenderScript mRs;
    Bitmap mBitmap;
    Bitmap mLutBitmap;
    ScriptIntrinsic3DLUT mScriptlut;
    Bitmap mOutputBitmap;
    Allocation mAllocIn;
    Allocation mAllocOut;
    Allocation mAllocCube;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        imageView1 = (ImageView) findViewById(R.id.imageView);
        mRs = RenderScript.create(this);
        Background background = new Background();
        background.execute();
    }

    class Background extends AsyncTask {

        @Override
        protected Void doInBackground(Void... params) {
            if (mRs == null) {
                mRs = RenderScript.create(MainActivity.this);
            }
            if (mBitmap == null) {
                mBitmap = BitmapFactory.decodeResource(getResources(),
                        R.drawable.bugs);

                mOutputBitmap = Bitmap.createBitmap(mBitmap.getWidth(), mBitmap.getHeight(), mBitmap.getConfig());

                mAllocIn = Allocation.createFromBitmap(mRs, mBitmap);
                mAllocOut = Allocation.createFromBitmap(mRs, mOutputBitmap);
            }
            if (mLutBitmap == null) {
                mLutBitmap = BitmapFactory.decodeResource(getResources(),
                        R.drawable.dawizfe);
                int w = mLutBitmap.getWidth();
                int h = mLutBitmap.getHeight();
                int redDim = w / 4;
                int greenDim = h / 4;
                int blueDim = 16;
                android.renderscript.Type.Builder tb = new Type.Builder(mRs, Element.U8_4(mRs));
                tb.setX(redDim);
                tb.setY(greenDim);
                tb.setZ(blueDim);
                Type t = tb.create();
                mAllocCube = Allocation.createTyped(mRs, t);
                int[] pixels = new int[w * h];
                int[] lut = new int[w * h];
                mLutBitmap.getPixels(pixels, 0, w, 0, 0, w, h);
                int i = 0;
                for (int r = 0; r < redDim; r++) {
                   for (int g = 0; g < greenDim; g++) {
                        for (int b = 0; b < blueDim; b++) {
                            int gdown = g / 4;
                            int gright = g % 4;
                            lut[i] = pixels[b + r * w + gdown * w * redDim + gright * blueDim];
                            i++;
                        }
                    }
                }
//                This is an identity 3D LUT
//                i = 0;
//                for (int r = 0; r < redDim; r++) {
//                    for (int g = 0; g < greenDim; g++) {
//                        for (int b = 0; b < blueDim; b++) {
//                            int bcol = (b * 255) / blueDim;
//                            int gcol = (g * 255) / greenDim;
//                            int rcol = (r * 255) / redDim;
//                            lut[i] = bcol | (gcol << 8) | (rcol << 16);
//                            i++;
//                        }
//                    }
//                }
                mAllocCube.copyFromUnchecked(lut);
            }
            if (mScriptlut == null) {
                mScriptlut = ScriptIntrinsic3DLUT.create(mRs, Element.U8_4(mRs));

            }
            mScriptlut.setLUT(mAllocCube);
            mScriptlut.forEach(mAllocIn, mAllocOut);

            mAllocOut.copyTo(mOutputBitmap);
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            imageView1.setImageBitmap(mOutputBitmap);
        }
    }
}