10 Replies Latest reply on Dec 31, 2015 3:10 PM by trshaner

    Slide scanning question

    sambucadog Level 1

      I've read similar posts on this, but not sure if I fully understand. I am scanning hundreds of old family slides at 3200dpi keeping the original slide dimensions in the Canoscan settings. I am bringing these into Lightroom 4 as a jpg, and cleaning up, cropping etc. My intent is to put the cleaned up jpgs (and the originals just in case) on discs to pass down to family members in the event they would like to reproduce them (in any print size they want) in the future without the aid of Lightroom.  My question is, when exporting, should I not resize (via long edge) at all, and does the dpi setting matter? In other words, if I export the 3200dpi cleaned up scan at the original dimensions but with a 300dpi output, will any resolution be lost if they want to blow up the slide sized image to 8x10? Hope this makes sense...thanks in advance.

      Monica

        • 1. Re: Slide scanning question
          JimHess Adobe Community Professional & MVP

          The DPI/PPI setting really doesn't matter. Regardless of the setting, the image will have the same number of pixels. In digital photography, that PPI (pixels per inch) setting has absolutely no impact on the quality of the image. It's only real value is to enable a program such as Photoshop to calculate how large the image will be at any given PPI setting.

          • 2. Re: Slide scanning question
            sambucadog Level 1

            so it only matters when I do the original scan to establish how large a small slide can be blown up and maintain quality?

            • 3. Re: Slide scanning question
              JimHess Adobe Community Professional & MVP

              Yes, that is exactly right. The higher the resolution during scanning, the larger the print that can be made. If you take one of those slides that you have scanned at 3200 PPI and open it in Photoshop and change the PPI setting to 300, then Photoshop will show you how large the image will be at that resolution. By changing the PPI setting doesn't change the number of pixels at all. The image is still exactly the same size.

              • 4. Re: Slide scanning question
                sambucadog Level 1

                OK, I think I get it. So once they are scanned, there is really no "best size" to export for my archive disc...saving them at a slide size is the same as saving them as an 8x10? (Thanks for your patience, it's just SO much work scanning these things that I want to be sure I'm storing them correctly!)

                • 5. Re: Slide scanning question
                  JimHess Adobe Community Professional & MVP

                  The only reason I would even consider changing the resolution setting is if for some reason there was a specific size I was looking for. If you simply store the images at the resolution they were scanned at you can be confident that any size print that you might want in the future can be ordered up to the limits of the file. 3200 PPI is really quite high. I know how long it must be taking you to do this. I did a scanning project at work a few years ago. I scanned 12,000 negatives, slides and prints. All of the negatives and slides were scanned at 2400 PPI. Most of the prints were scanned at 300 or 600 PPI. I didn't change the PPI settings when I handed the scanned images to our publications manager. She printed various sizes for large posters that were displayed in the hallways of our Department, and all of the images looked great. It was a challenging project that took 10 months of full-time work to complete.

                  • 6. Re: Slide scanning question
                    trshaner Adobe Community Professional & MVP

                    sambucadog wrote:

                     

                    I've read similar posts on this, but not sure if I fully understand. I am scanning hundreds of old family slides at 3200dpi keeping the original slide dimensions in the Canoscan settings.

                    What model Canon scanner are you using. For best results you should set the scanner resolution to even increments of the its native resolution. If your scanner's native resolution is 9600 x 9600 then it's best to use 9600, 4800, 2400, 1200, 600 resolution settings.

                    • 7. Re: Slide scanning question
                      sambucadog Level 1

                      It's a Canoscan 9000F. 3200 was one of the presets so I assumed it was ok..it can go up to 9600.

                      • 8. Re: Slide scanning question
                        trshaner Adobe Community Professional & MVP

                        I have the same scanner. The "in-between" output resolutions (6400, 3200, 1600, 800) require interpolations that may make the scan image slightly lower in "actual resolution." In reality this scanner can only achieve ~1,700 ppi resolution, which requires using the 4800 or 9600 setting. See "The image quality of the Canonscan 9000F" here:

                         

                        http://www.filmscanner.info/en/CanonCanoScan9000F.html

                         

                        I assume you are scanning 35mm slides. I get very good results using the 4800 output resolution setting with nothing to be gained going higher. It will take slightly longer to scan at the higher 4800 setting and the file size will be larger. Since you're using JPEG output format the files should still be relatively small compared to camera raw files. A 35mm mounted slide (~.9" x 1.4")  will produce an image file that is the equivalent of a ~3.6 Megapixel camera in "actual resolution" when scanned at 4800 dpi. The slides you have already scanned at 3200 ppi should be fine, but you will get the best results from this scanner at the 4800 setting. Why settle for anything less!

                        • 9. Re: Slide scanning question
                          sambucadog Level 1

                          Interesting...I'll bump it up to 4800. I don't understand how manufacturers can get away with advertising a product as scanning at a high resolution, and in reality it doesn't deliver anything even close to it.

                          • 10. Re: Slide scanning question
                            trshaner Adobe Community Professional & MVP

                            It's all marketing smoke and mirror–Optical Resolution versus Interpolated Resolution versus Reality. Flatbed scanners aren't the best choice for film scanning. I also own a Plustek OpticFilm 7600i film scanner with 7,600 ppi Optical Resolution. At the same site it was found to be ~3,400 ppi at the 7,600 ppi setting. It''s better than the Canonscan 9000F, but not by a lot considering how long it takes (1.5 to 3.0 minutes per 35mm slide). Here's what I'm using now–Scannerless Digital Capture. Way faster and way better results with both slides and negatives:

                             

                            Dropbox - Scannerless Digital Capture and Processing of Negative Film Photographs.pdf