android减少摄像头捕获图像的文件大小小于500 kb

Question

我的要求是将摄像头捕获的图像上传到服务器,但它应该小于500 KB.如果它大于500 KB,则需要将其减小到小于500 KB的大小(但稍微接近它)

为此,我使用以下代码 -

@Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        try {
            super.onActivityResult(requestCode, resultCode, data);
            if (resultCode == getActivity().RESULT_OK) {

                    if (requestCode == REQUEST_CODE_CAMERA) {

                        try {

                            photo = MediaStore.Images.Media.getBitmap(
                                    ctx.getContentResolver(), capturedImageUri);
                            String selectedImagePath = getRealPathFromURI(capturedImageUri);

                            img_file = new File(selectedImagePath);

                            Log.d("img_file_size", "file size in KBs (initially): " + (img_file.length()/1000));

                            if(CommonUtilities.isImageFileSizeGreaterThan500KB(img_file)) {
                                photo = CommonUtilities.getResizedBitmapLessThan500KB(photo, 500);
                            }
                            photo = CommonUtilities.getCorrectBitmap(photo, selectedImagePath);


//  // CALL THIS METHOD TO GET THE URI FROM THE BITMAP

                            img_file = new File(ctx.getCacheDir(), "image.jpg");
                            img_file.createNewFile();

//Convert bitmap to byte array
                            ByteArrayOutputStream bytes = new ByteArrayOutputStream();
                            photo.compress(Bitmap.CompressFormat.JPEG, 100, bytes);

//write the bytes in file
                            FileOutputStream fo = new FileOutputStream(img_file);
                            fo.write(bytes.toByteArray());

// remember close de FileOutput
                            fo.close();
                            Log.d("img_file_size", "file size in KBs after image manipulations: " + (img_file.length()/1000));


                        } catch (Exception e) {
                            Logs.setLogException(class_name, "onActivityResult(), when captured from camera", e);
                        }


                    } 

            }
        } catch (Exception e) {
            Logs.setLogException(class_name, "onActivityResult()", e);
        } catch (OutOfMemoryError e) {
            Logs.setLogError(class_name, "onActivityResult()", e);

        }
    }

和

public static Bitmap getResizedBitmapLessThan500KB(Bitmap image, int maxSize) {
        int width = image.getWidth();
        int height = image.getHeight();



        float bitmapRatio = (float)width / (float) height;
        if (bitmapRatio > 0) {
            width = maxSize;
            height = (int) (width / bitmapRatio);
        } else {
            height = maxSize;
            width = (int) (height * bitmapRatio);
        }
        Bitmap reduced_bitmap = Bitmap.createScaledBitmap(image, width, height, true);
        if(sizeOf(reduced_bitmap) > (500 * 1000)) {
            return getResizedBitmap(reduced_bitmap, maxSize);
        } else {
            return reduced_bitmap;
        }
    }

如果需要,旋转图像.

public static Bitmap getCorrectBitmap(Bitmap bitmap, String filePath) {
        ExifInterface ei;
        Bitmap rotatedBitmap = bitmap;
        try {
            ei = new ExifInterface(filePath);

            int orientation = ei.getAttributeInt(ExifInterface.TAG_ORIENTATION,
                    ExifInterface.ORIENTATION_NORMAL);
            Matrix matrix = new Matrix();
            switch (orientation) {
                case ExifInterface.ORIENTATION_ROTATE_90:
                    matrix.postRotate(90);
                    break;
                case ExifInterface.ORIENTATION_ROTATE_180:
                    matrix.postRotate(180);
                    break;
                case ExifInterface.ORIENTATION_ROTATE_270:
                    matrix.postRotate(270);
                    break;
            }

            rotatedBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return rotatedBitmap;
    }

这是最初和在减少文件大小的所有操作之后的图像文件大小的输出.

img_file_size:以KB为单位的文件大小(最初):3294

img_file_size:图像处理后的文件大小(KB):235

请参阅上面的差异(在输出中).没有那些操作的初始文件大小,以及那些压缩和其他操作之后.我需要这个尺寸有点接近500 kb.

上面的代码对我来说工作得有点好,因为它减少了图像文件的大小,使其小于500 KB.

但是,以下是上述代码的问题 -

• 此代码即使小于500 KB也会减小文件大小

• 如果它超过500 KB,减小的文件大小从500 KB变得太小,虽然我需要它更接近.

我需要摆脱2个问题.所以,需要知道我应该在上面的代码中操作什么.

因为我还想纠正EXIF方向(旋转图像),以及我上面提到的要求.

Answer 1

您可以在调整大小之前检查大小。如果位图的大小大于 500kb，则调整其大小。

同样为了使更大的位图更接近 500kb 大小，请检查大小之间的差异并相应地压缩。

if(sizeOf(reduced_bitmap) > (500 * 1024)) {
    return getResizedBitmap(reduced_bitmap, maxSize, sizeOf(reduced_bitmap));
} else {
    return reduced_bitmap;
}

并在 resize Bitmap 计算大小差异并相应地压缩