6 Replies Latest reply on Jun 23, 2015 11:31 AM by dj_paige

    Changing file size of a .TIFF?

    southwestform Level 1

      I need to keep a file under 100mb as a .tiff at a 8x10 specified size. What if anything can I do to decrease the file size without changing dimensions for the tiff?

       

      Thanks.

        • 1. Re: Changing file size of a .TIFF?
          JimHess Adobe Community Professional & MVP

          You cannot change the size of a file in Lightroom. However, you can export a copy of that file and control the size during the export process.

          • 2. Re: Changing file size of a .TIFF?
            Jao vdL Adobe Community Professional & MVP

            two factors affect the file size of a tif beside size in number of pixels. bit depth and compression. If you use 8bit in export your file size will go down a factor of two from 16 bits. Compression can gain you an even bigger factor. zip compression is usually the best and is lossless so there is no downside in using it.

             

            uncompressed file size is easy to calculate. If you have an 8-bit file at 8x10 and 300 ppi you get 8*10*300*300*3/1024/1024=20.6 MB. (Horizontal size*vertical size*ppi*ppi*number of color channels/bytes per kbyte/kbytes per MB) a uncompressed 16 bit file would be 41.2 MB. Using compression generally yields you a factor of 2 from that, so it appears that your file should always be small enough At 300 ppi.

            • 3. Re: Changing file size of a .TIFF?
              southwestform Level 1

              So I just exported a couple of files as TIFFs for printing and they were again too large. So I was about to switch from 16 bit to 8-bit when I realized, I have no idea how this is actually degrading the quality of the file.

               

              1. Does reducing from 16 or 8 bit only make a significant difference with prints above a certain size? In general, what is it doing to the file?

               

              2. I'm uploading .TIFF files to Costco's photo printing service and they have a file size limit of 100MB. I need these tomorrow, though in the future I'm going to look for a service without the file size limit. Any suggestions on places without limitations?

               

              Thanks!

              • 4. Re: Changing file size of a .TIFF?
                ManiacJoe Adobe Community Professional

                How big of a print are you looking to get from Costco?

                If you are looking at an 8x12 or smaller, an 8-bit JPG file at 90+% quality will easily look great; no need for a TIF file.

                 

                Can reducing the bit depth from 16 to 8 affect the image quality? Yes, but it is highly dependent on the image. If you have large expanse of a sky running from dark to light, you might see some banding.

                • 5. Re: Changing file size of a .TIFF?
                  dj_paige Level 9

                  1. Does reducing from 16 or 8 bit only make a significant difference with prints above a certain size? In general, what is it doing to the file?

                  I doubt you will see a difference in the prints. In general, it cuts the file size in half.

                   

                  See: What About 16-Bit for Printing? - Photo Tips @ Earthbound Light where the statement is made

                   

                  "how much of a difference does 16-bit printing make? I mean, if it produced noticeably superior results, wouldn't Epson provide support on both platforms? I'm not a Mac OS user so I can't compare directly myself, but I do know plenty of folks who are Mac users and have done so. Uniformly, they report little to no difference in side by side comparisons made with 8-bit and 16-bit drivers on OS X."

                   

                  They go on to explain that printing in 8 bits allows 16.7 million colors, and it's hard to image someone's eyeballs can distinguish that many colors visually. Going to 16 bits and 281 trillion colors makes no noticeable difference.

                  • 6. Re: Changing file size of a .TIFF?
                    dj_paige Level 9

                    Yes, but it is highly dependent on the image. If you have large expanse of a sky running from dark to light, you might see some banding.

                    This happens in editing, not in printing. If you don't see banding on the screen before you export and print, then you won't see banding in the print.