resize an image stored in byte array

[anuja Edathu]

Hello ,

i have a bean 'PhotoDetails' in which photo is a member of byte[]
i am retieving this object from database .
PhotoDetails objPhoto = dao.getPhotoDetails(Id);

before displaying this image i want to adjust the image size. can any one tell how can get the size of the image and resize it?

Thaks & Regards ,
Anuja Karthikeyan

[Peter Chase]

Well, you need to know what format (GIF, JPEG, TIFF etc.) your photo is in. If you don't know, and only have an array of bytes, your task is impossible (well, maybe you can "sniff" the format by looking at the bytes, but that's dodgy).

If you do know the format, you can read the bytes into a Java BufferedImage using ImageIO operations. When you have a BufferedImage, you can do things like AffineTransform on it, to change size, shape etc. Then you can write out to a different array of bytes, using ImageIO again.

[Jeff Albertson]

Originally posted by Peter Chase:
Well, you need to know what format (GIF, JPEG, TIFF etc.) your photo is in. If you don't know, and only have an array of bytes, your task is impossible (well, maybe you can "sniff" the format by looking at the bytes, but that's dodgy).

If you do know the format, you can read the bytes into a Java BufferedImage using ImageIO operations. When you have a BufferedImage, you can do things like AffineTransform on it, to change size, shape etc. Then you can write out to a different array of bytes, using ImageIO again.

ImageIO can do that sniffing for you!

[Peter Chase]

I knew that image files often contain initial bytes that identify the type of content. But I didn't know that such initial bytes would also be found in a byte array. I guess, though, that the byte array is often just the contents of some files, so it makes sense.

In that case, there's probably nothing wrong with "sniffing" the content type. It would still be safer to hard-code the content type if you know it will never change. I'd perhaps then suggest an assertion that checks that the hard-coded content type matches the "sniffed" one, where available.