File size different in LR than in "file info"

Question

After cropping an image (36MB) and doing some adjustments and then saving as a standard JPEG - high quality - I go back into LR and the new image shows it's 10.2 MB. When I quit LR and do a "get file info" on the same file it tells me that the image is 1.2 MB's. What gives?

Answer 1

Based only on what is included above, I would guess that the 36MB file was in RAW format which you then converted to a JPEG. Would that be correct? Going from 36MB to 12MB just doing a conversion to JPEG is not all that unusual. If you set up your camera to record both a RAW and a JPEG image for the same photo, you would see this sort of radical size difference because the lossy compression algorithms used in the conversion to JPEG will often just throw out up to 2/3 of your image data. The typical dSLR will record data at 12-bit or 14-bit color and Lightroom internally stores a RAW image at 16-bit color depth. A JPEG uses only an 8-bit color depth so there goes most of your data. Another thing to check is what resolution you used when you did the conversion. By default, the conversion is set up for screen which uses a resolution of 72-ppi. Great for display on the typical monitor but not much else. You will want to use at least 240-ppi for printing and 300-ppi for anything else.
Finally, unless you are intending to either send the photos to a web server or print them, I would not recommend converting them to JPEG. There is a massive loss of image data that is incurred and then, each time you save the image, it is compressed again and even more image data is lost. After the third compression, your JPEG image is pretty much useless as the quality is so bad. I convert my RAW images to DNG (my personal preference) and they are archived that way. When I am ready to print an image or send it to a web site, I export the image as a JPEG and store it separately, outside of my catalog though I will create a new collection for the image(s) or add them to an existing one so I know the status of the image but I always maintain the original in a RAW format.