Getting width/height of image without loading the whole thing...

[Chris Hollman]

For my application I am required to get the pixel dimensions of thousands of images of various formats as quickly as possible. Right now I am loading the image into a bitmap using standard .NET code (something like Dim img as Bitmap = Bitmap.FromFile(PathString), width = img.Width, etc...). This takes far too long, which is understandable because it is loading the image to be used and displayed, which I don't need to do, I only need those two pieces of data from it.

I understand I could parse the files myself byte by byte using descriptions of the various formats to decode the data and that would probably be faster, but I don't want to write methods to do that for a dozen different image formats. My question is is there a nice happy medium between the two options where I don't have to write manual file decoding for each format but where it also does not load the entire image and takes significantly less time than what I am doing currently?

Thank you in advance.

 

[JohnH]

See post 2 here about using the MS Shell library: http://www.vbdotnetforums.com/vb-net-general-discussion/47708-hot-get-mp3-file-value-rating.html
In your case you could use it to get the value from "Dimensions" column, which would be a string value in this form: ‪"328 x 490‬"

 

[Chris Hollman]

Nice that is exactly what I was looking for, and bonus, I also needed to get the run length of audio and video files and it looks like this method will work for that as well! Thank You!