我正在使用Whatsapp like image compression code来压缩从自定义相机拍摄的图像。
压缩后的图像看起来很模糊（很少淡出），看起来它的质量随着尺寸的变化而放松
Compress.java
public Bitmap compressImage(String 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 imgRatio = actualWidth / actualHeight;
float maxRatio = maxWidth / 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);
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();
}
FileOutputStream out = null;
String filename = getFilename();
try {
out = new FileOutputStream(filename);
// write the compressed bitmap at the destination specified by filename.
scaledBitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return getCompressesBitmap(filename);
}
public String getFilename() {
File file = new File(Environment.getExternalStorageDirectory().getPath(), "MyFolder/Images");
if (!file.exists()) {
file.mkdirs();
}
String uriSting = (file.getAbsolutePath() + "/" + System.currentTimeMillis() + ".jpg");
return uriSting;
}
private String getRealPathFromURI(String contentURI) {
Uri contentUri = Uri.parse(contentURI);
Cursor cursor = mContext.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 Bitmap getCompressesBitmap(String path) {
Bitmap bitmapImage = BitmapFactory.decodeFile(path);
int nh = (int) (bitmapImage.getHeight() * (512.0 / bitmapImage.getWidth()));
Bitmap scaled = Bitmap.createScaledBitmap(bitmapImage, 512, nh, true);
return scaled;
}
对此有任何解决方案吗？
答案 0 :(得分：1)
我认为你的相机图像已经被压缩了。因此，在您的自定义相机中设置高质量的图像捕获，因为上面的压缩代码工作正常，我已经测试过了。
答案 1 :(得分：0)
您可以在上述解决方案中更改的一件事是缩小图像的宽度和高度的硬编码值。尝试编写一个函数，以便在应用程序的SharedPreferences中启动应用程序时，以像素为单位存储手机的宽度和高度。在您设置缩小位图的宽度和高度的代码中，只需使用这些值。它将确保根据设备的硬件规格以最佳比例显示图像，而不会导致任何内存不足异常并提供最佳压缩。