12 Replies Latest reply on Aug 3, 2014 8:28 AM by CL_Dandy

    original and effective ppi

    CL_Dandy

      Hey everyone! I would like to ask for some urgent help on Indesign + PDF print document subject.

      I prepared a document for offset print (business cards 8,5cm width x 5,5cm height) and it turned out that the pictures were very rastered on the Proof. Like, you could see the raster dots on it.

      I checked out my Indesign document again and I found out that the original ppi of the images was 762 and the effective ppi over 1000. I then realised that on Photoshop, I setted by mistake the pictures´s resolution for 300 pixel per cm instead of pixel per inchs!!

      I changed that and they have now:

      300 pixel per inch resolution

      4cm width x 5cm height

      and the pixel dimensions are: 472 px width x 591 pixel (height).


      In the Indesign document, it appears now:

      300 original ppi

      between 300 and 400 effective ppi

      472 px x 591 px dimensions


      My question is, do you guys think I solved the problem that way or should I still change something before I sent it again to print?

      The real dimensions of the pictures on the business card should be about 4cm width x 5cm height, so I decided to have them on Photoshop with that dimensions and 300 pixel per inch resolution, so that I don´t have to scale them much on Indesign. Did I do it right?


      Thank you!

        • 1. Re: original and effective ppi
          Salah Fadlabi Level 5
          so I decided to have them on Photoshop with that dimensions and 300 pixel per inch resolution, so that I don´t have to scale them much on Indesign. Did I do it right?

          If the resolution on the links panel:Effective PPI is 300 or more , there's no problem.

          • 2. Re: original and effective ppi
            Peter Spier Most Valuable Participant (Moderator)

            Except if you radically down-sampled them to achieve this resolution you are going to have the same loss of detail. How do they look now in the PDF?

            • 3. Re: original and effective ppi
              CL_Dandy Level 1

              that´s what I´m worried about, that now I reduced them too much.

              So this is what I did:

              I had the pictures originally on Photoshop with 762 pixel per inch / 300 pixel per cm (because I thought I setted it for pixel per inch).

              Then, I changed the resolution on that file for 300 pixel per inch. I reduced all the layers (with masks, etc.) to only one and then dragged it to another photoshop document with 4cm width x 5cm height and 300 pixel per inch resolution. That´s the photoshop file I have now on my Indesign document.

              At 100% view they look okay, but still I think they lost detail :/

              • 4. Re: original and effective ppi
                Peter Spier Most Valuable Participant (Moderator)

                Of course they lost detail. You threw away more than half the pixels. But the only place to judge accurately is the PDF viewed at 100%.

                • 5. Re: original and effective ppi
                  CL_Dandy Level 1

                  It´s hard to tell for sure because the business cards are 8,5cm width x 5,5cm height and at 100% view the pictures look ok but yet not sure.

                  The psd file which had 762 and I reduced for 300 pixel per inch still has good detail quality, but when I dragged the final layer to the psd file with 4cm width x 5cm height and 300 px per inch resolution, it doesn´t look that great anymore. This psd file at 100% look ok but I think it should have more detail quality.

                  Is there another way I should use instead to correct this inch/cm mistake? I still have the old files. Or should I drag the final layer to a psd file with more width and height?

                  • 6. Re: original and effective ppi
                    Peter Spier Most Valuable Participant (Moderator)

                    Do you have the original file from BEFORE you set the resolution to 300 ppCM? What is the image size and resolution of that when you open it in Photoshop?

                    • 7. Re: original and effective ppi
                      CL_Dandy Level 1

                      Yes I still have the original psd file!

                      Image size: 14,8 cm width x 21 cm height

                      Resolution: 762 px / inch ( = 300px/cm )

                      • 8. Re: original and effective ppi
                        CL_Dandy Level 1

                        Also, do you think that the main problem on the print (that the pictures came out with raster dots on the proof), is due to the original psd files having 762 px per Inch instead of 300?

                        • 9. Re: original and effective ppi
                          CL_Dandy Level 1

                          The original psd file has, more precisely:

                          Image size: 14,8 cm width x 21 cm height

                          Resolution: 762 px / inch ( = 300px/cm )

                          Pixel dimensions: 4440 x 6300

                           

                          Then, I changed the Resolution from 762 px / inch to 300 px / inch, and checked in the "resample image" option, which converted the Pixel dimensions into: 1748 x 1418

                          (Image size remained the same)

                          This file has good detail quality, it looks sharp.

                           

                          Then, I drag the layer from this file to a new one, with the image size I need :

                          Image size: 4cm x 5cm

                          Resolution: 300 px / inch

                          Pixel dimensions: 472 x 591

                           

                          Which makes me think of another question: Are these Pixel dimensions enough for print? Is this psd file good enough to place in Indesign and for print?

                          • 10. Re: original and effective ppi
                            Peter Spier Most Valuable Participant (Moderator)

                            OK, the original image is 4440 x 6300 pixels. At 300 PPI that translates to a physical dimension of approximately 37 x 53 cm, or nearly 10 times the height of the business card (if you are rotating the the card to horizontal).  Since this image is actually big enough to print a small poster, there is essentially no way you can use all, or even a major portion of this image without it being downsampled, either by you or by the RIP when it is printed, so there is going to be some loss of detail. Right now you've downsampled twice, once when you checked the box and set the resolution to 300 PPI, and again when you put it in the smaller file. Whether that works better than simply resetting the size to 4 x 5 @ 118.11ppcm/300ppi is doubtful.  Be sure you save with a new name so you don't destroy the big version, and don't save as a jpeg.

                             

                            The only way you will know if this is satisfactory is to make a proof. If the cards are to be printed digitally, your own laser printer should be adequate for the proof. Offset is likely to show better detail, so if it looks good on a laser printer it should also look good on press.

                            • 11. Re: original and effective ppi
                              Peter Spier Most Valuable Participant (Moderator)

                              Pixel dimensions, by themselves are meaningless for print. It's a matter of how densely you pack those pixels into a given space (the effective resolution). The rule of thumb for offset is 2 x linescreen for images viewed at arm's length, which generally gets interpreted to mean 300 ppi with a standard 150 lpi screen in commercial print. Rules of thumb are just generalities, and the actual image and print method, as well as intended viewing distance all play a role in the optimum resolution.

                              • 12. Re: original and effective ppi
                                CL_Dandy Level 1

                                I made a test right now. I resetted the original psd file to 4 x 5 @ 118.11ppcm/300ppi, checking the "resample Image" box and I notice loss of detail.

                                Meaning, this one lost more detail than the smaller file I created.