Does Compression degrade digital photos?

Running ATI 9, latest build. I am a photographer using RAW, BMP, TIFF and JPEG digital photo files--often up to 40 meg per file. Does enabling compression in ATI version 9 degrade the quality of the photo--i.e. is digital data permanently lost (ie when uncompressing and restoring)? thanks

 

You could do a files/folder backup of a photo-filled folder with max compression and then restore to a different location and compare.

 

No, because the file is restored to exactly the same bytes as it was before it was compressed. If this didn't happen, spreadsheet files for example would be all wrong.

You are thinking of a lossy method of compression where actual bits of data are discarded with no way to be recovered again such as the compression algorithm used with jpeg files.

If you don't believe me, download a checksum calculator and calculate the checksum for one of your files. Now backup and restore with TI and calculate the checksum again. It will be the same.

Here is one:
http://www.irnis.net/soft/xcsc/