It’s more than an Image – EXIF metadata

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One of the interesting features that impressed me a lot when I started to upload photos on Flickr is that it gives details of the image such as when it was taken, make of the camera that it was taken, exposure time, model, focal length and etc..

Some time back this was requirement in one of our projects as well. Where we allow our users to upload photos to the system and then the system should be able to track and show details of the photo to the administrator in case if it’s required to trace the person and the camera from which it was taken. Because this web based solution was actually developed for the use of police. Hence the administrator will be one of them as well.

So we actually wanted to track details of such as the make of the camera from which it was taken, the date and time it was taken and the focal length of the camera and so on. So when I first saw this on Flickr I was over the moon that it was possible. And I started digging on it. But unfortunately we couldn’t implement it on our system as we ran out of time preparing it for an exhibition, working on a tight schedule (Had to carry out this project in a span of mere two weeks amidst of lectures and all at that time).

Coming to the business end, the technology behind it was very simple yet it could be used to produce some amazing results. At the ground it’s not a technology, it’s actually a standard called EXIF (Exchangeable Image File Format).

According to the convention there are serious of attributes that can be associated with an image which if you are interested can read it on its declaration. There, these attributes are categorized into 5 catagaories.

And only the mandatory ones are a must to implement if any camera maker wants to stick to it. But more often than not you will get to see the comments of the photographer and the manufacturer of the camera as well though these are not madatory according to the Specification. And the documentation also lists of serious of attributes where those attribute values should be encrypted. And comments fall into this category.

Though it was a PHP implemented on Flickr, And we also initially wanted to do it using PHP, I have used java to check on it as I’m working with java a lot these days. So to do this one obviously requires a java API. After googling it for a while I was able to find two such libraries and chose to stick with Sanselan. As it looked simple, and it had relatively more features compared to the other such as writing such metadata to an image and so on.

That’s all what I required to start coding a tiny application to check on it. And below shown is a screenshot of it. As it was mentioned above, since comments are encrypted you want be able to read it here (it’s not in a human readable manner but if you can no harm go ahead and read it). Still it’s possible to read comments as well.

A screen shot of the Application

a screen shot of the application

Download the Application requires java runtime environment (JRE 1.4 or later).

The Image

image.jpg

Here exif image width and exif iamge length refers to the width and the height of the image in pixels.

Pixel :- Pixel comes from Picture element and it is known to be the building block of an image.

Acknowledgements

The image was taken from deviantart, thanks janati. Image looks fantastic ha!. Hope you will find it interesting, feel free to drop in your feedbacks.

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