Convert Byte Array to image in Java - without knowing the type

Question

Sounds simple right? Use

ImageIO.read(new ByteArrayInputStream(bytes));

Here's the wrinkle. For some reason it is detecting a jpeg as a bmp, and that is the first ImageReader returned when I call

ImageInputStream iis = ImageIO.createImageInputStream(new ByteArrayInputStream(bytes));
Iterator<ImageReader> readers=ImageIO.getImageReaders(iis);

This causes the image to come out corrupted. Is there a way to tell through java short of looking directly at the bytes for the header, and failing that does anyone know of a good reference for the byte headers for the different images?

Just letting you guys know I am still working on this. I'll let you know if/when I have an answer. I thank all of you for your responses so far.

This page might be a good starting point for magic numbers. Here is something similar from Wikipedia. — R Ubben
– R Ubben, Commented Jul 31, 2009 at 14:44

jedierikb · Accepted Answer · 2009-07-31 14:42:59Z

3

Haven't played with ImageIO in a awhile, and have not tested this, but I seem to recall something like this working. (since you say you know your file is a jpg and not a bitmap, I am using that information to help find the right loader).

String inFormat = "jpg";

Iterator inReaders = ImageIO.getImageReadersByFormatName(inFormat);

...

nextInReader.setInput( iis );

answered Jul 31, 2009 at 14:42

jedierikb

13.2k24 gold badges103 silver badges172 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

PHeath Over a year ago

That's correct but the problem is the data collection is a mix of bmp, png, jpg, etc. So any of them COULD be valid, the trick is telling which one solely based upon the bytes.

mic.sca · Accepted Answer · 2009-07-31 14:48:34Z

0

For the reference you can have a look at wikipedia, you can find the header of the different formats there.
http://en.wikipedia.org/wiki/Graphics_Interchange_Format
http://en.wikipedia.org/wiki/BMP_file_format
http://en.wikipedia.org/wiki/JPEG

answered Jul 31, 2009 at 14:48

mic.sca

1,6882 gold badges19 silver badges34 bronze badges

Comments

Michael Borgwardt · Accepted Answer · 2009-07-31 14:49:51Z

-1

Is the BMP reader the only one returned by getImageReaders()? Maybe you get more than one and can make a choice based on that.

answered Jul 31, 2009 at 14:49

Michael Borgwardt

347k81 gold badges491 silver badges726 bronze badges

Collectives™ on Stack Overflow

Convert Byte Array to image in Java - without knowing the type

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related