Resizing pictures while still preserving quality in android

问题

I want to reduce the image file size below 100 KB while preserving the image quality like whatsapp and facebook did.

I tried almost all the code of android image compression available on stackoverflow but that doesn't work for me.

Right now i am following this blog to reduce the image size, and i am getting the image below 100 KB but image quality is poor.

Is there any way that i can reduce image size below 100 KB while preserving the quality??? (Original Image size can vary from 20 KB to 8 MB)

I tried JAI library in Java Project, and it work good.

Can i Use JAI library in android to reduce image size???

Thanks in Advance.

Source Code to compress an Image:

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.math.BigInteger;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.media.ExifInterface;
import android.os.Environment;
import android.util.Log;

public class CompressBitmap {

    private String path;
    public CompressBitmap(String path){
        this.path= path;
    }

    public ByteArrayOutputStream getBitmap(){
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        getscaledImage(path).compress(Bitmap.CompressFormat.JPEG, 100, outStream);
        return outStream;
    }

    public ByteArrayOutputStream getBitmap(int quality){
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        getscaledImage(path).compress(Bitmap.CompressFormat.JPEG, quality, outStream);  
        return outStream;
    }

    public String getComressFile(){
        FileOutputStream out = null;
        String filename = createImageFile();
        try {
            out = new FileOutputStream(filename);
            getscaledImage(path).compress(Bitmap.CompressFormat.JPEG, 80, out);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        File file = new File(filename);
        Log.e("SIze of Image","Length"+file.length());
        return filename;
    }

    private Bitmap getscaledImage(String filePath){
        Bitmap scaledBitmap = null;

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;                      
        Bitmap bmp = BitmapFactory.decodeFile(filePath,options);

        int actualHeight = options.outHeight;
        int actualWidth = options.outWidth;
        float maxHeight = 800.0f;
        float maxWidth = 600.0f;
        float imgRatio = actualWidth / actualHeight;
        float maxRatio = maxWidth / maxHeight;

        Log.v("Pictures", "Before scaling Width and height are " + actualWidth + "--" + actualHeight);

        if (actualHeight > maxHeight || actualWidth > maxWidth) {
            if (imgRatio < maxRatio) {
                imgRatio = maxHeight / actualHeight;
                actualWidth = (int) (imgRatio * actualWidth);
                actualHeight = (int) maxHeight;
            } else if (imgRatio > maxRatio) {
                imgRatio = maxWidth / actualWidth;
                actualHeight = (int) (imgRatio * actualHeight);
                actualWidth = (int) maxWidth;
            } else {
                actualHeight = (int) maxHeight;
                actualWidth = (int) maxWidth;     
            }
        }

        options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight);
        options.inJustDecodeBounds = false;
        options.inDither = false;
        options.inPurgeable = true;
        options.inInputShareable = true;
        options.inTempStorage = new byte[16*1024];

        try{    
            bmp = BitmapFactory.decodeFile(filePath,options);
        }
        catch(OutOfMemoryError exception){
            exception.printStackTrace();

        }
        try{
            scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888);
        }
        catch(OutOfMemoryError exception){
            exception.printStackTrace();
        }

        float ratioX = actualWidth / (float) options.outWidth;
        float ratioY = actualHeight / (float)options.outHeight;
        float middleX = actualWidth / 2.0f;
        float middleY = actualHeight / 2.0f;

        Matrix scaleMatrix = new Matrix();
        scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);

        Canvas canvas = new Canvas(scaledBitmap);
        canvas.setMatrix(scaleMatrix);
        canvas.drawBitmap(bmp, middleX - bmp.getWidth()/2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));

        Log.v("Pictures", "After scaling Width and height are " + scaledBitmap.getWidth() + "--" + scaledBitmap.getHeight());

        ExifInterface exif;
        try {
            exif = new ExifInterface(filePath);

            int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 0);
            Log.d("EXIF", "Exif: " + orientation);
            Matrix matrix = new Matrix();
            if (orientation == 6) {
                matrix.postRotate(90);
                Log.d("EXIF", "Exif: " + orientation);
            } else if (orientation == 3) {
                matrix.postRotate(180);
                Log.d("EXIF", "Exif: " + orientation);
            } else if (orientation == 8) {
                matrix.postRotate(270);
                Log.d("EXIF", "Exif: " + orientation);
            }
            scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
        } catch (IOException e) {
            e.printStackTrace();
        }

        return scaledBitmap;
    }

    private String createImageFile(){
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss",Locale.getDefault()).format(new Date());
            String imageFileName = "JPEG_" + timeStamp + "_";
            File storageDir = Environment.getExternalStoragePublicDirectory(
                    Environment.DIRECTORY_PICTURES);
            File image;
            try {
                image = File.createTempFile(
                    imageFileName,  /* prefix */
                    ".jpg",         /* suffix */
                    storageDir      /* directory */
                );
                return image.getAbsolutePath();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
    }

    private int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int heightRatio = Math.round((float) height / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }
        final float totalPixels = width * height;
        final float totalReqPixelsCap = reqWidth * reqHeight * 2;

        while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
            inSampleSize++;
        }
        return inSampleSize;
    }
}

public void getBase64() {
    CompressBitmap compressBitmap =  new CompressBitmap(picturePath);  
    //display compressBitmap in ImageView.

    byte[] bytes=null;

    File file= new File(picturePath);               

    ByteArrayOutputStream bos = compressBitmap.getBitmap();
    bytes = bos.toByteArray(); 
    base64 = Base64.encodeToString(bytes, Base64.DEFAULT);

    return base64;   // send base64 String on server
}

回答1:

Missing seems:

options.inPreferQualityOverSpeed = true;

来源：https://stackoverflow.com/questions/25244799/resizing-pictures-while-still-preserving-quality-in-android