7 Replies Latest reply on Sep 19, 2016 2:14 AM by MorganMills

    Lightroom Exporting: Tiny file sizes

    MorganMills

      Evening,

       

      I recently began using Lightroom after years of using Photoshop. One thing I'm finding hard to understand is the exporting.

       

      After simply editing a portrait as my first practice in Lightroom, I saved the file as 100% quality and JPEG. This resulted in a tiny file size of 872 KB. Confused, I replicated the simple editing process in Photoshop, saved it as a JPEG at full quality and this resulted in a file size of 9 MB.

       

      Side by side, zoomed in, I can't see any difference in quality. I did notice that the Lightroom saved image has 240 dpi and the Photoshop image has 72 dpi.

       

      I then went back to Lightroom and saved the same image as .TIF, resulting in a file size of 107 MB with no visible improvements in quality.

       

      Is Lightroom known for tiny file sizes? Am I doing something wrong? I don't understand why, how and what is going on with Lightroom's exporting and file sizes. I'd love an explanation.

        • 1. Re: Lightroom Exporting: Tiny file sizes
          Per Berntsen Adobe Community Professional

          It sounds like you checked Resize to fit, or checked Limit file size to ... in the Lightroom export dialog.

          Other than that, file size is not a good indicator of image quality - pixel dimensions are.

          Also, ppi is meaningless and irrelevant unless you are going to print the image. Ppi is metadata used by printer drivers to calculate the physical dimensions of the print.

           

          Tiff files have a much bigger file size than jpgs because they are either uncompressed, or use lossless compression, that is much less effective than the jpg (lossy) compression. Tiff files can also be 16-bit, which are twice the size of 8-bit files.

           

          Take a look at

          What is a digital image?

          File formats

          Lightroom basics

          1 person found this helpful
          • 2. Re: Lightroom Exporting: Tiny file sizes
            MorganMills Level 1

            Thanks for the speedy reply. I didn't check either of those check boxes. I've had a good scour of the web already but I haven't seen why the file sizes are so dramatically different to Photoshop for an image of the same dimensions and no crop etc.

            • 3. Re: Lightroom Exporting: Tiny file sizes
              Per Berntsen Adobe Community Professional

              I did a test saving a jpg at maximum quality from Lightroom and Photoshop, and they are exactly the same file size.

              So what are the pixel dimensions of your exported jpgs? Are they the same?

              And where are you checking the file size?

              Photoshop will show you the uncompressed file size, and to see the size on disk (compressed file size) you have to use Windows Explorer or the Mac Finder.

              • 4. Re: Lightroom Exporting: Tiny file sizes
                Jao vdL Adobe Community Professional & MVP

                First thing to understand is that with jpeg, file size is only tangentially related to quality. You can't use it as an indicator. If you have large expanses of solid color, they will compress really well. On the other hand, if you have a lot of noise in your image, it will not compress well and you'll end up with a very big file. So the larger file will have the worst quality comparing those two. That said, 872 kb was highly likely a scaled down image. It is highly unlikely you would get such a tiny file from a full resolution export. On a computer screen you likely wouldn't see any difference between the two as computer screens have very low resolution. Only when you would zoom in would you see the Lightroom export doesn't scale but the Photoshop export does. I would export again, making sure the scale option is unchecked. You should get a file of a few to 20 MBs for most types of images. Also, there is generally no reason to use quality 100. There are very few images that benefit from anything above 85. You save a factor of two in file size with no perceptible loss of quality.

                • 5. Re: Lightroom Exporting: Tiny file sizes
                  MorganMills Level 1

                  Yeah, pixel dimensions are the same. Approx 5000 x 3000 pixels. No visible differences in resolution when zooming in. I check the file size of the edited image in file explorer., using Properties.

                  • 6. Re: Lightroom Exporting: Tiny file sizes
                    trshaner Adobe Community Professional & MVP

                    MorganMills wrote:

                     

                    Yeah, pixel dimensions are the same. Approx 5000 x 3000 pixels. No visible differences in resolution when zooming in. I check the file size of the edited image in file explorer., using Properties.

                    You need to view the image at 1:1 Zoom View to determine the actual image quality. The only way you wouldn't see a difference in image quality between a 9MB full-size JPEG export and 872KB full-size JPEG export is if the image has very low detail (i.e. shot in the fog or out of focus). I suggest posting the a LR Export JPEG at 100 Quality and PS JPEG at 12 Quality to Dropbox or other file sharing site. Any subject will do as long as there is plenty detail in the image. You can place the file share links in a reply here.

                    • 7. Re: Lightroom Exporting: Tiny file sizes
                      MorganMills Level 1

                      After exporting the image several times, I checked the file sizes and they were roughly the same as the original image again. I don't know why the file sizes were so small - maybe my computer was having a wobbly moment. I've continued editing with Lightroom and haven't had the same issue again.

                       

                      Thanks for your help, anyway.