Decode byte array to bitmap that has been compressed in Java
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I didn't realise that the background of my bitmap (from a Canvas object) was transparent. Since this bitmap is just black lines on a white background the black image is due to compressing to JPEG giving the image a black background.
I have changed
bmpSig.compress(Bitmap.CompressFormat.JPEG, 100, out);
to
bmpSig.compress(Bitmap.CompressFormat.PNG, 100, out);
And it is working as expected.
Author by
cutts
Updated on June 17, 2022Comments
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cutts almost 2 years
I am compressing a bitmap in the following way
Bitmap bmpSig = getMyBitMap(); int size = bmpSig.getWidth() * bmpSig.getHeight(); ByteArrayOutputStream out = new ByteArrayOutputStream(size); bmpSig.compress(Bitmap.CompressFormat.JPEG, 100, out); byte[] bytSig = out.toByteArray();
I am then trying to display the image in an Android ImageView from the byte array. When I do this I get an image that is completely black image.
ImageView myImg = (ImageView) findViewById(R.id.img_view); myImg.setImageBitmap(BitmapFactory.decodeByteArray(bytSig, 0, bytSig.length));
I'm assuming it's because I am missing a step before BitmapFactory.decodeByteArray() to reverse the jpeg compression. Or have I misunderstood how the compression works?