How to convert image file data in a byte array to a Bitmap?

Question

I want to store image in SQLite DataBase. I tried to store it using BLOB and String, in both cases it store the image and can retrieve it but when i convert it to Bitmap using BitmapFactory.decodeByteArray(...) it return null.

I have used this code, but it returns null

Bitmap  bitmap = BitmapFactory.decodeByteArray(blob, 0, blob.length);

Please read the first 5-10 links in the "Related" section on this page. — Mat, Oct 01 '11 at 13:11

score 308 · Accepted Answer · edited Jul 31 '16 at 15:30

308

Just try this:

Bitmap bitmap = BitmapFactory.decodeFile("/path/images/image.jpg");
ByteArrayOutputStream blob = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0 /* Ignored for PNGs */, blob);
byte[] bitmapdata = blob.toByteArray();

If bitmapdata is the byte array then getting Bitmap is done like this:

Bitmap bitmap = BitmapFactory.decodeByteArray(bitmapdata, 0, bitmapdata.length);

Returns the decoded Bitmap, or null if the image could not be decoded.

edited Jul 31 '16 at 15:30

manfcas

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answered Oct 01 '11 at 13:41

Uttam

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image could not be decoded if it is in other format that you are trying to decode from – lxknvlk Mar 28 '15 at 12:23
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What if I need to perform such an operation many times in sequence? Isn't it resource-consuming to create new Bitmap object every time? Can I somehow decode my array into existing bitmap? – Alex Semeniuk Apr 16 '15 at 11:27
I post a different answer when you just have a buffer of the image pixel. I was getting always null because of the lack of with, height and color in my buffer. Hope it helps! – Julian Nov 30 '16 at 07:19

score 38 · Answer 2 · edited Jun 06 '18 at 23:48

38

The answer of Uttam didnt work for me. I just got null when I do:

Bitmap bitmap = BitmapFactory.decodeByteArray(bitmapdata, 0, bitmapdata.length);

In my case, bitmapdata only has the buffer of the pixels, so it is imposible for the function decodeByteArray to guess which the width, the height and the color bits use. So I tried this and it worked:

//Create bitmap with width, height, and 4 bytes color (RGBA)    
Bitmap bmp = Bitmap.createBitmap(imageWidth, imageHeight, Bitmap.Config.ARGB_8888);
ByteBuffer buffer = ByteBuffer.wrap(bitmapdata);
bmp.copyPixelsFromBuffer(buffer);

Check https://developer.android.com/reference/android/graphics/Bitmap.Config.html for different color options

edited Jun 06 '18 at 23:48

Derzu

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answered Nov 30 '16 at 07:17

Julian

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what is mBitmaps? – user924 Apr 04 '18 at 09:55
@Julian How to byte[] cannot be cast to java.lang.String when retreving image from Sqlite https://stackoverflow.com/questions/63658886/android-byte-cannot-be-cast-to-java-lang-integer?noredirect=1#comment112570298_63658886 – Kingg Aug 30 '20 at 16:03

How to convert image file data in a byte array to a Bitmap?

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