Question

I'm currently working with JPEG's, and when I use Lightroom to edit my photos with Exposure, my file size is much smaller than it was when I started. Why is this happening and am I loosing any quality in my image.

Answer

The simple answer is yes, you are losing quality, though you may not see it in the beginning. JPEG's are a compressed file type, and whenever you use lossy compression on a file, you are losing information. The best solution for this problem is to use a different format. I recommend TIFF for editing. Once complete, you can render out JPEGs as a final step.

Here you can see an example of JPEG compression.

Uncompressed image                                           Compressed image

Here are a few things to keep in mind about each file type:

JPEG

1. Lossy compression
   • Loss of quality
   • File size reduced even when using Photoshop
2. Thumbnails may not display properly
3. No support for layers
4. Great for use on the web
5. Small file sizes

TIFF