How can I read image metadata from binary blobs?

Question

I have some images (in PNG and JPG format), stored as blobs in the database. I am retrieving them with a query and would like to take action by reading the metadata without writing the image to disk.

I am looking for the file type and image width.

Answer 1

You should be abe to convert the data to a ColdFusion Image type using the ImageNew function as documented here (set the source to be the variable you pulled out of the query).

Once you have the image, you can use the ImageInfo function to retrieve image properties.

This will give you the width. CF won't tell you the original file format, though--it might be easiest to look at magic numbers for that. Wikipedia gives a good summary of what those are and what the values for jpeg and png are: http://en.wikipedia.org/wiki/Magic_number_(programming)