Digital Film compresion

I'm guessing that you mean photos! What format are your files ie JPG, TIF, BMP,RAW?

LMiller7 said:

The effectiveness of file compression depends greatly on the type of file. Some files, such as standard text files, compress very well. Others, such as many image, music, and video files are already compressed and attempts at further compression produce little if any gain.

It's not strictly true that you can't compress Image files. I have two files one a copy of the other. One file is 6.6MB and the other is 924KB. They are both 3648 x 2736 pixels.
But lets wait and see what the OP says!

Sorry didn't mean my post to sound harsh! You are perfectly correct. Although it is correct to say that a file format like JPEG that is already a compressed file cannot be compressed again to say a RAR or ZIP file you can reduce the file size but of course if you do that and save the file to the original file name and location that will overwrite the original. So it isn't compressing in the conventional sense. But as I say lets see what the op comes up with.

Or are you asking about video?
I'm not exactly clear.

RalphG said:

I am talking about video.

Then all you can do is to check the bit rate of each file and see if that can be reduced whilst still retaining an acceptable quality level. You can also change the bit rate from a definite rate to a variable ate but this does depend on the video content.
There are, of course, many free "video converters" available that will reduce the file size of you videos. However you need to remember that every time you re render a ideo file you loose quality even if you render to the same format as the original. Rendering to a different format to reduce the file size will always reduce the quality often to an unviewable state. it might help if we knew where these files came from, are they your own home miovies or downloaded from the internet or what?