I have tried several different methods found in the java documentation, as well as several solutions from other SO questions and have successfully gotten a Bitmap to convert to a byte[] and back again.
The problem is that I now need to convert this byte[] to a String, then back to a byte[], then back to a Bitmap again. To recap what I need:
Bitmap -> byte[] -> String -> byte[] -> Bitmap
I know this sounds strange but what I'm trying to accomplish must be done this way. Below is what I have tried, if anyone could point out what I'm doing wrong I'd greatly appreciate it!
Bitmap bitmap = mv.getDrawingCache();
// Convert bitmap to byte[]
ByteArrayOutputStream output = new ByteArrayOutputStream(bitmap.getByteCount());
bitmap.compress(Bitmap.CompressFormat.PNG, 100, output);
byte[] imageBytes = output.toByteArray();
// Convert byte[] to string
// I have also tried using Base64.encodeToString(imageBytes, 0);
String encodedString = new String(imageBytes);
// Convert string to byte[]
byte[] newImageBytes = encodedString.getBytes();
if (imageBytes == newImageBytes) {
Toast.makeText(SignatureActivity.this, "SUCCESS!!", Toast.LENGTH_SHORT).show();
} else { // Sadly, we always get to this point :(
Toast.makeText(SignatureActivity.this, "BOOO", Toast.LENGTH_SHORT).show();
}
// Convert byte[] back to bitmap
bitmap = BitmapFactory.decodeByteArray(newImageBytes, 0, newImageBytes.length);
Again, going Bitmap -> byte[] -> Bitmap was successful, but adding in the conversion to a String and back is causing the final Bitmap to write an image of 0kb.
The problem is not in the conversion, but how you verify the result. using == to compare two arrays only returns true if they are the same array reference. Since you create a new array with byte[] newImageBytes = encodedString.getBytes(); This will always be false.
See this question for reference.
On another note, if you are going to transfer or use the string in some way, it is probably better to use Base64.encodeToString(imageBytes, Base64.NO_WRAP); to get a string, and get it back with Base64.decode(encodedString, Base64.NO_WRAP).
You can also get the byte array without compressing it, with the copyPixelsToBuffer() method (see this question for an example).
Related
I am trying to pass an image from java to flutter. The image is in bitmap in java so I first try to convert it to bytes[] using:
on java side:
int byteCount = transferredImage.getAllocationByteCount(); // transferredImage is the bitmap
ByteBuffer buffer = ByteBuffer.allocate(byteCount); //Create a new buffer
transferredImage.copyPixelsToBuffer(buffer);
byte[] myByte = buffer.array();
Then on flutter side I read the image as Uint8List and create an img.Image object from it:
img.Image styleImage = img.Image.fromBytes(
imgWidth,
imgHeight,
transferredBytes,
);
This works, without causing any errors but the image displayed using Image.memory(img.encodeJpg(styleImage)) always has a blue tint. The bitmap on java side is fine but when converted to bytes[] and displayed in flutter it has a blue tint..
So I assumed some important information may have been dropped during conversion to bytes using my above method, I then convert the image to an image format and then transfer the bytes:
at java side:
ByteArrayOutputStream baos = new ByteArrayOutputStream();
transferredImage.compress(Bitmap.CompressFormat.PNG, 100, baos);
byte bytes []= baos.toByteArray();
on flutter side:
img.Image styleImage = img.Image.fromBytes(
imgWidth,
imgHeight,
transferredBytes,
);
But this does not work and creates an error:
RangeError (index): Index out of range: index should be less than
321512: 322560
If possible, I would prefer to have my first attempt work as it is really fast, so is there any way I can get this to work ?
Thanks
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 2 years ago.
Improve this question
How to convert Image to String and vice versa in java.
I convert a file.jpg to byte array and then convert byte array to String, but when I reconvert the result String to Image, I got error
Here is code
public void StringToFile( String s1, String filename ) {
byte[] byte02 = s1.getBytes( );
//byte[] byte02 = s1.getBytes( StandardCharsets.UTF_8 );
try {
System.out.println( "Data is corrupted when converting image "
+ "file to String and vice versa, this function is just a test" );
FileOutputStream output = new FileOutputStream( filename );
output.write( byte02 );
output.close();
ByteArrayInputStream bis = new ByteArrayInputStream( byte02 );
BufferedImage bImage2 = ImageIO.read( bis );
ImageIO.write( bImage2, "jpg", new File( filename ) );
}
catch ( Exception ex ) {
System.out.println( ex.getMessage() );
}
}
It can cause problems when you convert binary data into an regular string.
The reason is that converting a byte array into an String converts the bytes into characters using the character encoding of the system. Bytes that have no character mapped to it will be lost or modified in the process.
Instead I'd suggest you use
java.util.Base64.getEncoder().encodeToString(byte[])
to convert the file's bytes into a string value and
java.util.Base64.getDecoder().decode(String)
to get the value back into bytes.
If possible, avoid converting binary data like a graphics file to String. String is meant to contain a sequence of Unicode characters, and not arbitrary data. If you need to transform binary data into printable characters, use the approach given in the the answer by Roland Kreuzer, namely an encoding like base 64.
On Android, to convert a Bitmap to byte[], you can use the Bitmap.compress method:
import android.graphics.Bitmap;
private byte[] getBytesFromImage (Bitmap image) {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.PNG, 0, outputStream);
return outputStream.toByteArray();
}
This method returns a byte[] array which you can use to store the image in your Database, for instance, as a Blob value.
To convert the byte[] to an Image, use the BitmapFactory.decodeByteArray method:
BitmapFactory.decodeByteArrray(imageBytes, 0, imageBytes.length); // imageBytes is the byte[] array of the image that was returned by the getBytesFromImage method.
When i make upload of a image in Android to the server (C #) it generates an error converting the image to byte Array, this happens with some images which is very strange because this error is not always generated, that is, depending the image is correctly converted or not.
The conversion code:
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bitmapPhoto.compress(Bitmap.CompressFormat.JPEG, 50, stream);
final byte[] img_byte = stream.toByteArray();
final String imageString = Base64.encodeToString(img_byte, Base64.DEFAULT);
When receiving in C# I make the following conversion in the string, generating a byte Array and then for the MemoryStream.
byte[] novaFoto = Convert.FromBase64String(NovaFoto.FotoString);
using (MemoryStream stream = new MemoryStream(novaFoto))
{
Image image = Image.FromStream(stream);
}
depending at the image the error appears in either Convert.FromBase64String or Image.FromStream.
Can anyone help me with this? If you have another method i like this.Thanks!!
I need convert byte array (byte[]) (from java BufferedImage) to EmguCV Image without to know the width and height.
byte[] bytes = [data];
Image<Gray, byte> image = new Image<Gray, byte>();
image.Bytes = bytes;
Can you help me?
I found this
[ http://www.emgu.com/forum/viewtopic.php?t=1057 ]
public Image<Bgr, Byte> byteArrayToImage(byte[] byteArrayIn)
{
MemoryStream ms = new MemoryStream(byteArrayIn);
Bitmap returnImage = Image.FromStream(ms);
return new Image<Bgr, byte>(returnImage);
// you probably need to clean up stuff like the bitmap and the stream...
}
On the emgu forum and retyped it to remove a variable-name typo. Assuming your byte array is a standard image , looks like you can load it into a standard image variable that will automatically figure out sizing. From there you could pass that image to the constructor of your emgu image.
I develop a custom messenger application which sends message from client(Android) to another client(web). My problem is when I send image file, I encoded it to Base64 string and then send it to another client. When the recipient client is Android, the app successfully decoded the Base64 String to bitmap image. But when the recipient client is web app, the web application failed to decode and display it using :
<img id="img" src="data:image/jpeg;base64,3iVBORw0KGgoAAAANSU...">
My Java encode/decode method
public static Bitmap base64StringToBitmap(String base64) {
byte[] bytes = Base64.decode(base64, Base64.URL_SAFE);
return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
}
public static String bitmapToBase64String(Bitmap bmp, Bitmap.CompressFormat format, int quality) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bmp.compress(format, quality, baos);
byte[] bytes = baos.toByteArray();
return Base64.encodeToString(bytes, Base64.URL_SAFE);
}
I've tried to change the encoding method to Base64.DEFAULT, but still the Base64 String cannot be displayed in HTML using data:image/jpeg;base64. Is there any differences between Android Base64 string and Base64 string used to display image in HTML? Please suggest me the solution. Thanks
EDIT :
This is the base64 string example generated from my Android application, with padding. I failed to display it on html/web, although it can be displayed fine on Android :
3iVBORw0KGgoAAAANSUhEUgAAAF8AAABfCAYAAACOTBv1AAAABHNCSVQICAgIfAhkiAAAChtJREFU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I had a similar issue where I wanted to convert an Android generated BASE64 string to Binary with Javascript and atob function was keep giving me errors. My first guess was like yours to use URL_SAFE instead of DEFAULT, but none of them worked, then I figure it out that I need to use Base64.NO_WRAP method to get it working.
I tested Base64.NO_WRAP and displaying inline image and IT WORKED!!!!
Hope this save you some nerves, because I did had some till I figure it out how to do it.
So to give the nice answer, change: return Base64.encodeToString(bytes, Base64.URL_SAFE); to this: return Base64.encodeToString(bytes, Base64.NO_WRAP);
E
can you try with this for me it's working fine one two change only Base64.DEFAULT insted of URL_SAFE and image tag alt. just check it.
<img height=700px src='data:image/jpg;base64,"+encodeString+"' alt='Embeded Image'/>
public static String bitmapToBase64String(Bitmap bmp, Bitmap.CompressFormat format, int quality) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bmp.compress(format, quality, baos);
byte[] bytes = baos.toByteArray();
return Base64.encodeToString(bytes, Base64.DEFAULT);
}