Image scale without loss of image quality does not work

Question

Does anyone know how to scale a bitmap without losing image quality? I am currently facing this problem where the size of the selected image, perhaps too large, made the application return to another action.

So, now I tried to use this method to scale the selected image without losing its quality. I get the code here .

protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); switch (requestCode) { case RESULT_LOAD_IMAGE: if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK & null != data) { Uri selectedImage = data.getData(); String[] filePathColumn = {MediaStore.Images.Media.DATA}; Cursor cursor = getContentResolver() .query(selectedImage, filePathColumn, null, null, null); cursor.moveToFirst(); int columnIndex = cursor.getColumnIndex(filePathColumn[0]); String picturePath = cursor.getString(columnIndex); cursor.close(); Bitmap a = (BitmapFactory.decodeFile(picturePath)); photo = scaleBitmap(a, 200, 200); imageView.setImageBitmap(photo); } break; } public static Bitmap scaleBitmap(Bitmap bitmap, int newWidth, int newHeight) { Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Bitmap.Config.ARGB_8888); float scaleX = newWidth / (float) bitmap.getWidth(); float scaleY = newHeight / (float) bitmap.getHeight(); float pivotX = 0; float pivotY = 0; Matrix scaleMatrix = new Matrix(); scaleMatrix.setScale(scaleX, scaleY, pivotX, pivotY); Canvas canvas = new Canvas(scaledBitmap); canvas.setMatrix(scaleMatrix); canvas.drawBitmap(bitmap, 0, 0, new Paint(Paint.FILTER_BITMAP_FLAG)); return scaledBitmap; } 

The answer seems useful to most people, but why doesn’t this work for me? Did I miss something?

source image

selected image image in imageView

Answer 1

Please, try

 public Bitmap scaleBitmap(Bitmap bitmap,int newWidth,int newHeight) { Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Config.ARGB_8888); float ratioX = newWidth / (float) bitmap.getWidth(); float ratioY = newHeight / (float) bitmap.getHeight(); float middleX = newWidth / 2.0f; float middleY = newHeight / 2.0f; Matrix scaleMatrix = new Matrix(); scaleMatrix.setScale(ratioX, ratioY, middleX, middleY); Canvas canvas = new Canvas(scaledBitmap); canvas.setMatrix(scaleMatrix); canvas.drawBitmap(bitmap, middleX - bitmap.getWidth() / 2, middleY - bitmap.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG)); return scaledBitmap; } 

Answer 2

Try this to scale the bitmap

 public static Bitmap scaleBitmap(Bitmap bitmap, int newWidth, int newHeight) { float scaleX = ((float)newWidth) / bitmap.getWidth(); float scaleY = ((float)newHeight) / bitmap.getHeight(); Matrix scaleMatrix = new Matrix(); scaleMatrix.postScale(scaleX, scaleY); Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight() , scaleMatrix, true); return scaledBitmap; } 

Answer 3

 Use this it will definitely help you to reduce the size without loosing quality. public Bitmap compressImage(String imageUri) { String filePath = imageUri; // String filePath = getRealPathFromURI(imageUri); Bitmap scaledBitmap = null; BitmapFactory.Options options = new BitmapFactory.Options(); // by setting this field as true, the actual bitmap pixels are not // loaded in the memory. Just the bounds are loaded. If // you try the use the bitmap here, you will get null. options.inJustDecodeBounds = true; Bitmap bmp = BitmapFactory.decodeFile(filePath, options); int actualHeight = options.outHeight; int actualWidth = options.outWidth; // max Height and width values of the compressed image is taken as // 816x612 /* * float maxHeight = 816.0f; float maxWidth = 612.0f; */ float maxHeight = 1080.0f; float maxWidth = 800.0f; float imgRatio = actualWidth / (float) actualHeight; float maxRatio = maxWidth / (float) maxHeight; // width and height values are set maintaining the aspect ratio of the // image 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; } } // setting inSampleSize value allows to load a scaled down version of // the original image options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight); // inJustDecodeBounds set to false to load the actual bitmap options.inJustDecodeBounds = false; // this options allow android to claim the bitmap memory if it runs low // on memory options.inPurgeable = true; options.inInputShareable = true; options.inTempStorage = new byte[16 * 1024]; try { // load the bitmap from its path 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)); // check the rotation of the image and display it properly ExifInterface exif; try { exif = new ExifInterface(filePath); int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 0); displayLogs("EXIF", "Exif: " + orientation); Matrix matrix = new Matrix(); if (orientation == 6) { matrix.postRotate(90); displayLogs("EXIF", "Exif: " + orientation); } else if (orientation == 3) { matrix.postRotate(180); displayLogs("EXIF", "Exif: " + orientation); } else if (orientation == 8) { matrix.postRotate(270); displayLogs("EXIF", "Exif: " + orientation); } scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true); } catch (IOException e) { e.printStackTrace(); } FileOutputStream out = null; String filename = getFilename(filePath); // File image = new File(getFilename(), System.currentTimeMillis() + // ".jpg"); try { out = new FileOutputStream(filename); // write the compressed bitmap at the destination specified by // filename. boolean didWrite = scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out); out.close(); System.out.println(didWrite); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return scaledBitmap; } private String getRealPathFromURI(String contentURI) { Uri contentUri = Uri.parse(contentURI); Cursor cursor = getContentResolver().query(contentUri, null, null, null, null); if (cursor == null) { return contentUri.getPath(); } else { cursor.moveToFirst(); int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA); return cursor.getString(index); } } public 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 String getFilename(String originalname) { ImageCache imageCache = new ImageCache(this); File file = new File("Your folder path"); // return file; String uriSting = (file.getAbsolutePath() + "/" + "F_" + System.currentTimeMillis() + ".png"); return uriSting; } 

Answer 4

Your problem is that you are not preserving the aspect ratio of the original image. in your code, if you need a width of 200, then the height should be calculated as follows:

 newHeight = ((float) originalHeight/(float) originalWidth) * (float) newWidth; 

So in your case:

 float newHeight = ((float) a.getHeight()/(float) a.getWidth()) * (float) 200; 

And then call the zoom function with width:200 and height calculated from the original value.

After that, if the quality is still poor, experiment with increasing the width and stop when you get the quality you need.

Answer 5

While you have too many large images at a time, you must Be sure to manage the Bitmap cache policy. Managing the cache is too much. On Android, we have one excellent Picasso library. This library provides built-in cache management. this will control your bitmap in the background, as well as provide an image cache function. When your image is uploaded, and again you upload the same image, it will be in the cache. Built-in functionality does not need to change code.

I hope you understand my decision. Best of luck