Using compression when creating an image

Being a keen photographer with alot of JPEGs saved, can anyone tell me whether data is lost when restoring these files from a compressed image.

How does the compression work -does it drop pixels from the JPEG files.

I've considered saving an uncompressed image of my hard drive but the Acronis software said it was going to take 9 hours! so opted for 'Normal' compression instead.

 

That's really more than one question. (drive)Image compression does not in any way affect the quality of your images. It also will be very ineffective in compressing JPG files, as they are already compressed. About all it will do is remove the few vacant sectors that are left over at the end of each file (un-used cluster space), maybe a few percent in space will be recovered. Same is true of video files, audio, etc. Compression is most effective on OS and program folders where there is a lot of wasted space.

 

Thanks rd, sounds like I dont need to worry about loss of JPEG quality from what you've wriiten.

 

That's correct. While JPEG compression is lossy, the type of compression used by TrueImage is lossless. Not one bit is changed or removed between the original and the restored image.

 

Thanks, am reassured.

Can I ask, in view of the compression being lossless, is there ever any advantage in using the 'no compression' mode when creating the image.

Similarly, why not have 'maximum' compression rather than just 'normal'?

 

Speed mainly. Compression uses processor time, and slows the image process. Try it on your image files, it may be faster with no compression since they won't compress much anyway. And you may want to try incremental images after that to avoid the lengthy process.

 

Well, when I used Ghost a while back, I always ran into problems when I used their high compression mode. So because of that bad experience, when using ATI I've kept it at "Normal". NOT to say that ATI has this same problem (it probably doesn't). As a matter of fact, so far everything about ATI works great. But I can't afford to have that happen to me again.

I know, I'm probably worrying about this needlessly...