35 Replies Latest reply on Jul 19, 2015 2:12 PM by perrybrus

    Digital publishing - why not 72dpi?

    perrybrus Level 1

      When choosing Digital Publishing in the document setup, I notice that one of the formats is 1024x768 px. A typical and average screen resolution in many parts of the world. But the document doesn't turn to 72dpi instead of 300? When I copy 8pt txt from one document at 1024x768px over to a standard A4 print document it doesn't change visually. It looks the same size. There's really no way to switch document resolution in ID like you can in for instance PS, where you can manually set the document resolution based on the purpose of the job when you open a document. As far as I understand the document resolution in terms of dpi is 300 by set default in ID? If the Digital Publishing documents are made at 300dpi but drawn to a pixel size of whatever you choose, then we still have to operate with highres images cause the document does not simulate the lower resolution.

       

      Comments?

        • 1. Re: Digital publishing - why not 72dpi?
          rob day Adobe Community Professional & MVP

          An InDesign page has no resolution, You can place an image at any resolution on a page, so a document can have multiple images with varying effective resolutions (the scaled resolution). When you export a document to PDF you can choose to keep the effective resolutions or downs sample them to a chosen resolution.

           

          You can specify the page's dimensions as pixels and as an output measurement a pixel equals 1/72". So at 100% a 1024x768 page always outputs as 14.22"x10.66" . When you spec type the size is relative to print output. 8pt type won't change size when you paste it into a document with smaller dimensions

          • 2. Re: Digital publishing - why not 72dpi?
            perrybrus Level 1

            Hi,

             

            Thanks for your feedback. I know that I'm able to place any image resolution in a document. I also know that a typesize wont' change when I place it in another document that has smaller dimensions, but I did it to see if the document resolution was smaller by default when opening a "digital document." If it were then I would get a visual response right away. So my experience made me think that this "digital document" concept wasn't well adjusted. I will have to continue to use highres images in order to retrieve placement sufficiency. When I place a 72dpi image within a 300dpi document it won't occupy as much document space as if it was a 300dpi image file when used in 100% of its original size. The lowres image will look smaller and "run out of pixels" earlier than a highres image of course. Same effect you can see when you use PS to open a 72dpi document and a 300dpi document and start placing lowres images in the highres document. I hope I'm explaining myself clear enough here.

             

            When I work with documents in PS that's intended for digital media I don't open a document in 150, 200 or 300dpi - so why can't we do the same in ID when working with files intended for digital displays? And what is the native resolution of the IN documents? Sorry, I didn't get your calculation theory at all. Algorithmic calculations are not my strongest side. And I can't really see where its possible to alter the document dpi setting in the PDF export dialog? I only see image compression alterations based on dpi settings.

            • 3. Re: Digital publishing - why not 72dpi?
              rob day Adobe Community Professional & MVP

              How have you determined that your document has a resolution of 300ppi? InDesign pages have no resolution—they are not bitmaps. It's like Illustrator not Photoshop, where the page can contain both bitmap images (of any resolution) and vector art.

               

              If you want to rasterize a page you can export it  to a bitmap format like PNG or JPEG and the export dialog will let you choose the desired output resolution.

              • 4. Re: Digital publishing - why not 72dpi?
                perrybrus Level 1

                I don't know if you actually meant to write "they are not bitmaps" - cause ID is not an image format, its a layout application that supports all image formats - both bitmap and vectors. In order to be able to cater for print production the starting point must contain some sort of document resolution information and according to Adobe that's 300dpi for Illustrator. Based on that I presumed that ID had the same "engine" so to speak. As I explained there's no reason to operate with more than 72dpi for what ID define as a "digital format" meant for displays and not print. I still think my question is legit. PS supports the same file formats as ID, both bitmap and vectors. I know that PS is calculating vectors somewhat different than ILLU and ID, but it still supports them all. But with PS its possible to adjust the document resolution based on whatever media you are going to. When ID released the "digital format" document it would be reasonable to believe that the actual resolution of that documents corresponded with the resolution of the end media so that it's possible to use lighter files etc. The good thing about PS is that I can use lowres images in my documents because the document corresponds with the image format resolution I have in hand, its so much easier to work like that cause I guess 85% of all the images I have available for web projects are 72dpi and not 100, 150, 180, 200, 300 or whatever. It's a practical issue as I elaborated on in my former post. Altering the document resolution in the export sessions doesn't solve that issue.

                • 5. Re: Digital publishing - why not 72dpi?
                  Peter Spier Most Valuable Participant (Moderator)

                  As Rob said, InDesign files have no resolution, only a physical output dimension (ID was developed as a PRINT layout application). The screen work capabilities are more or less "tacked on" and for convenience, ID has adopted a 1:1 correspondence between Postscript Points (72/inch) and pixels when setting up rulers, but documents built in pixels still are considered to have physical dimension and can be printed as if they are measured in points.

                  • 6. Re: Digital publishing - why not 72dpi?
                    rob day Adobe Community Professional & MVP

                    In order to be able to cater for print production the starting point must contain some sort of document resolution information and according to Adobe that's 300dpi for Illustrator.

                     

                    Where are you seeing that? Illustrator's document setup lets you set a resolution for Raster Effects, but that only applies to items you convert to rasters under the Effects menu.

                     

                    When you output a page to print, the print driver and its PPD determines the output resolution of the halftone (LPI) or stochastic screen required for printing the page. It's the printer's resolution capability (DPI) that determines what the maximum output screen resolution can be.

                     

                    You can set an InDesign document's ruler units to pixels and then set the page dimension to any pixel dimension. As Peter mentioned InDesign sets the output dimension of a pixel unit as 1/72". If you wanted to display a page in a browser you would have to rasterize it via JPEG, PNG or PDF-to-Photoshop. So a 1024x768 pixel document exported at 72ppi will open in Photoshop as 1024x768.

                     

                    If you export to EPUB the XHTML's body and viewport width and height style will match the InDesign page's pixel dimensions. The pixel dimensions of images or converted vectors are determined by the resolution you set in the export dialog's Conversion Settings. If you have a placed image that is 1"x1" and choose 150ppi as the Resolution setting the image will export as 150x150 pixels

                    • 7. Re: Digital publishing - why not 72dpi?
                      perrybrus Level 1

                      I see that I have to reset my thinking in terms of digital documents vs ID. I'm having problems grasping the technical aspects of this but I will try to learn more. Bottom point as I read this is that's it's no "default document resolution" in ID and its not possible to alter this within the application itself like I can in PS. I have never tweaked the document resolution in the PDF export session before, so I obviously need to read up on this topic. I find it quite cumbersome to work with 72dpi images in ID because of the size complex, and that's the only image resolution I have available for this digital document.

                       

                      Thanks for trying to explain the complexity of this topic. The headline in my initial post was why not 72dpi? - I guess it's been explained by the fact that there is no document resolution in ID like you have in PS.

                      • 8. Re: Digital publishing - why not 72dpi?
                        rob day Adobe Community Professional & MVP

                        What kind of document are you trying to create? HTML, EPUB, PDF, DPS, print? If you are designing for screens you have to choose a target pixel dimension for the page and you'll have to export at some point.

                        • 9. Re: Digital publishing - why not 72dpi?
                          Peter Spier Most Valuable Participant (Moderator)

                          This script from Jongware will re-scale any bitmap image to the effective resolution of your choice:

                           

                          // by jongware
                          
                          
                          var theImage = null; 
                          if (app.selection.length > 0) 
                          { 
                            if (app.selection[0].constructor.name == "Image") 
                            { 
                              theImage = app.selection[0]; 
                            } else 
                            { 
                              try 
                              { 
                                theImage = app.selection[0].images[0]; 
                              } catch (e) 
                              { 
                                theImage = null; 
                              } 
                            } 
                          } 
                          if (theImage == null) 
                          { 
                            alert ("Not a bitmap image"); 
                          } else 
                          { 
                            var ppiDialog = app.dialogs.add({name:"Change image ppi",canCancel:true}); 
                            with(ppiDialog) 
                            { 
                              with(dialogColumns.add()) 
                              { 
                                staticTexts.add({staticLabel:"Actual ppi: "+theImage.actualPpi}); 
                                staticTexts.add({staticLabel:"Current ppi: "+theImage.effectivePpi}); 
                                with(dialogRows.add()) 
                                { 
                                  staticTexts.add({staticLabel:"Set to"}); 
                                  var resolution = realEditboxes.add({editValue:theImage.effectivePpi[0], minwidth:100}); 
                                } 
                              } 
                            } 
                            var result = ppiDialog.show(); 
                            if (result) 
                            { 
                              theImage.absoluteHorizontalScale = theImage.actualPpi[0]*100/resolution.editValue;
                              theImage.absoluteVerticalScale = theImage.actualPpi[1]*100/resolution.editValue;
                            } 
                          } 
                          

                           

                          It runs in CS5, but I haven't tried it in later versions, though putting it in a "Version 7.0" (case sensitive, but witout the quotes) subfolder should allow it to run in newer versions if it throws an error. It does not resize the frame, however. I expect that would be a simple enough addition, as would be stepping through all the images in a document or page, but I don't write scripts. You can ask over in InDesign Scripting

                          • 10. Re: Digital publishing - why not 72dpi?
                            perrybrus Level 1

                            I'm just trying to see if I can create a digital document with a screen only purpose. A PDF that's only meant to be displayed and assessed on screens. I then want to see if I can export it to a standard format such as epub. The aim was to be able to work with lower resolution graphics as that is what I normally have at hand. I very rarely have anything larger than 72dpi files and nothing I make in ID gets printed, so I want to resolve this by working with image formats that correspond with the resolution that I'm actually working at. Just like I do in PS. I tough it was possible to do this in the application and work 1:1 - I wasn't aware that "digital documents" in ID meant just pixel dimensions with no adjustment of document resolution. If its only possible to change the document resolution after I'm done designing the document, then it won't solve the issue that I have cause then I will have to use highres images all the way anyhow. As mentioned, a 72dpi image in a document that is way larger than 72dpi will look small. This is why I find it more practical to do one pagers in PS where I'm actually allowed to establish a document resolution to fit my needs, but when I need more documents to build a publication ID is the better app. I'm just learning that it is not possible to adjust the document resolution the same way as I do in PS and that the "digital document" feature in ID is not a 72dpi document. I've learned trough this forum that things are more complex than that in ID.

                            • 11. Re: Digital publishing - why not 72dpi?
                              rob day Adobe Community Professional & MVP

                              Acrobat doesn't have a document resolution either, so I'm not sure why you have to worry about the incoming resolution other than if there will be enough when the user zooms in on an image—but you have no control over the user's zoom choice. You can scale a placed image to any size you want and the Info panel will show you its effective resolution, which accounts for the scale.

                               

                              If by 1:1 you mean Photoshop's 100% view where one image pixel equals one monitor pixel, you have to consider that neither InDesign's (CS6 and later) or Acrobat's 100% view is 1:1—by default 100% in both displays the actual print output size.

                              • 12. Re: Digital publishing - why not 72dpi?
                                perrybrus Level 1

                                I don't think you understand my dilemma. Either that or I'm totally unaware of my own lack of knowledge here. If so then please forgive me.

                                 

                                Its about the opportunity to use 72dpi images in a 72dpi document. My images gets way too small in my actual layout when the document is holding a higher resolution than my images. Try dropping a 72dpi image in a 300 dpi document in PS, then you will see what I mean. I can't layout my 72dpi images and make them occupy a 1:1 ratio placement in ID when theres a difference between my image resolution and my document resolution, although the ID native document is not at a set resolution like I initially thought, its higher than 72 dpi cause ID is aimed at print media. When I try out the digital document (as its called in ID) I don't do that necessarily to export it as epub or any other digital format, I'm mostly trying to utilize my lowres images as my design is very much about bitmaps and not vectors, and my documents never gets to see a printer. It's all for screen view. If I had access to highres images I would use them instead, but in my case all I receive is 72dpi images cause my vendor is exclusively operating in the web media, so 72dpi is what I have to work with.

                                • 13. Re: Digital publishing - why not 72dpi?
                                  Peter Spier Most Valuable Participant (Moderator)

                                  What intent did you use when creating the file?  Waht are the ruler units in use? What are the page dimensions? Waht are the pixel dimensions of the image? What is the effective ppi after you place it?

                                  • 14. Re: Digital publishing - why not 72dpi?
                                    perrybrus Level 1

                                    The images are all 72dpi.It doesn't matter what ruler units I have, the outcome is the same. As you can see Arnold doesn't look quite as impressive at "full print resolution" and that is the closest I get to emulate ID native document resolution. Intent creates the same dilemma on both Digital publishing and Web. These documents are created in PS. The forum rescales large images substantially, but I just wanted to illustrate the dilemma.

                                     

                                    docex01.jpg docex02.jpg

                                    • 15. Re: Digital publishing - why not 72dpi?
                                      Peter Spier Most Valuable Participant (Moderator)

                                      You are doing something odd. Please show us the Info panel with each of those images selected.

                                      • 16. Re: Digital publishing - why not 72dpi?
                                        perrybrus Level 1

                                        Nothing odd about this. I've added a 72dpi image at 450x337px at 72ppi to an A4 document as described. One is at 300ppi. The other at 72ppi.

                                         

                                        info01.gifinfo02.gif

                                        • 17. Re: Digital publishing - why not 72dpi?
                                          Peter Spier Most Valuable Participant (Moderator)

                                          I want to see the info panel in ID, not Photoshop, with the images selected...

                                          • 18. Re: Digital publishing - why not 72dpi?
                                            Peter Spier Most Valuable Participant (Moderator)

                                            And the tow Photoshop panels you are showing are clearly not the same image.

                                            • 19. Re: Digital publishing - why not 72dpi?
                                              perrybrus Level 1

                                              This is showing an entire document. The info is not the image alone. I am trying to visually explain to you what type of dilemma I'm referring to by comparing one document that has the measure properties as described, and the other at lower resolution. The image of Arnold is at 450x337px (72ppi) placed within these two different documents. The image is exactly the same and this is exactly the dilemma I have when using ID. My 72ppi images are too small for the "native resolution" of the ID documents. The digital documents doesn't change in terms of resolution, so I'm stuck with the dilemma you can see illustrated by the two document graphics. Don't know of a better way to describe this. Two copies of the same image placed in to different documents. One document is at the same resolution as the image (72ppi) - the document at typical high quality print resolution, or "native ID resolution" in a lack of a better word. 

                                              • 20. Re: Digital publishing - why not 72dpi?
                                                Peter Spier Most Valuable Participant (Moderator)

                                                Until you provide what I ask for I cannot help you.

                                                • 21. Re: Digital publishing - why not 72dpi?
                                                  rob day Adobe Community Professional & MVP

                                                  One is at 300ppi. The other at 72ppi.

                                                  If you set your InDesign rulers to inches you'll see the problem. Remember in InDesign a pixel as a unit of measurement always 1/72", so you have two documents with very different output dimensions.

                                                   

                                                  The InDesign document you've set to 2480x3508 pixels has an output dimension of 34.444" x 48.722" (2480/72=34.444), while the 595 x 842 version would output at 8.2639" x 11.6944". You are placing an image with the same output dimension of 6.292"x4.75" in both, so of course it looks relatively larger in the smaller document.

                                                  • 22. Re: Digital publishing - why not 72dpi?
                                                    Peter Spier Most Valuable Participant (Moderator)

                                                    One more time. ID files have no resolution, only dimensions.

                                                     

                                                    A4 is 595.276 x 841.89 pts, so would round to the 595 x 842 pixels you show. I have no idea what that 2480 x 3508 number represents, but it certainly isn't an A4 document. Without knowing the actual and effective resolution of the images, AS PLACED in the document, it's impossible to tell if they have been scaled, and how much.

                                                    • 24. Re: Digital publishing - why not 72dpi?
                                                      perrybrus Level 1

                                                      You are very wrong about that. This is rather straight forward. Photoshop calculates these document sizes, so unless Adobe has done some major wrongs in the way they calculate images the numbers are correct. You can try this yourself by opening an A4 document at 300ppi and an A4 document at 72ppi. It's pretty easy to do and you will see what Photoshop calculates. Then add an image at 72ppi to both thise documents. I have no clue what you are talking about I'm afraid. The images is not rescaled. It is added to the document as is. The pixel dimensions I quoted are correct.

                                                      • 25. Re: Digital publishing - why not 72dpi?
                                                        perrybrus Level 1

                                                        As I wrote. These document files are not made in ID but in PS. There's no way to reproduce these document files in ID for the same reason Im trying to explain.

                                                        • 27. Re: Digital publishing - why not 72dpi?
                                                          perrybrus Level 1

                                                          Let's just rap it up. Thanks for participating. The conclusions is rather simple: ID is not the right tool for this job. I'll make my 12 pager in PS, that way I can work on a 72ppi document with my 72ppi images.

                                                          • 28. Re: Digital publishing - why not 72dpi?
                                                            rob day Adobe Community Professional & MVP

                                                            As I wrote. These document files are not made in ID but in PS

                                                            What you are showing is expected behavior in either program—you are pasting an image with the same pixel dimensions into two very different sized documents.

                                                             

                                                            I can do the same thing in InDesign:

                                                             

                                                            Screen Shot 2015-07-18 at 8.10.09 PM.png

                                                            • 29. Re: Digital publishing - why not 72dpi?
                                                              perrybrus Level 1

                                                              Yes rob, but your documents have the same document resolution. My two PS documents were made from a 300ppi document and a 72ppi document. As this thread has clearly shown theres no way of altering the document resolution in ID. The "digital document" or the "Web" document in ID does not correspond with the 72ppi native screen resolution (yes I know some displays are at 96 or 98ppi now). A web page document at 1024x768 made in ID is not at 72ppi. As I only have 72ppi images available for my projects I like to work on a document that corresponds with my image resolution, my two documents made from 300ppi and 72ppi demonstrates my point. The image of Arnold is identical in terms of percentage and size in both those documents.

                                                               

                                                              Anyways, thanks for your input. Have a nice night / day.

                                                              • 30. Re: Digital publishing - why not 72dpi?
                                                                rob day Adobe Community Professional & MVP

                                                                The relationship in both cases is pixel dimensions not ppi. My InDesign documents have two very different pixel dimensions as do your two PS files. If you make a 1024x768 pixel doc in InDesign it's pixel dimensions are exactly 1024x768 at 72ppi. If you place a 1024x768, 72ppi image in the 1024x768 doc, the page dimensions an image dimensions will match.

                                                                • 31. Re: Digital publishing - why not 72dpi?
                                                                  rob day Adobe Community Professional & MVP

                                                                  The image of Arnold is identical in terms of percentage and size in both those documents.

                                                                  To maintain the percentage relationship the pasted image would have to be up sampled to 300ppi., which would create quality problems.

                                                                  • 32. Re: Digital publishing - why not 72dpi?
                                                                    perrybrus Level 1

                                                                    Rob, the images are THE SAME in both my documents. They are not altered. As you can read from my post the pixel dimensions on the Arnold images are the same and its in 72ppi. You have seen info palettes from both PS and ID. The documents I shared are both viewed at 100%. The forum does not allow me to post the actual document at its full size, thats why I wrote the measurements in the document graphics. Please read all the posts in this thread if you want further descriptions.

                                                                     

                                                                    As I don't think we are making any progress this way I chose to conclude yesterday and I rapped it up. Again, I'm going to make my project in a 72dpi document in PS. No worries The world goes on. Again, thanks for the contribution.

                                                                    • 33. Re: Digital publishing - why not 72dpi?
                                                                      Peter Spier Most Valuable Participant (Moderator)

                                                                      The reason you are not making progress is you are not listening to what is being said and you are conflating document dimensions with document resolution. Yes, unlike ID, Photoshop documents have a resolution, but they have no physical dimensions, only pixel dimensions, and pixels do not have a "size." Your A4 @ 300 ppi is not the same as your A4 at 72 ppi, and neither one has any physical size until printed. If both are printed full size to fill an A4 sheet, the pixel density (the space on the page that each pixel takes up) will be larger or smaller according to the pixel dimensions of your image and the physical space (the A4 sheet) that those pixels are required to fill. You  can take the any image and change its resolution in Photoshop without resampling, and the pixel dimensions and the actual pixels will not vary.

                                                                       

                                                                      ID documents have no pixel resolution, only a physical dimension. ID reads the saved resolution information in your image (the Actual Resolution) and calculates how large that should be physically on your page. If you change the physical size (scale the image), ID also reports the new output resolution as a different Effective Resolution.

                                                                      • 34. Re: Digital publishing - why not 72dpi?
                                                                        rob day Adobe Community Professional & MVP

                                                                        The documents I shared are both viewed at 100%.

                                                                         

                                                                        That would be impossible.

                                                                         

                                                                        Photoshop's 100% view is 1:1 image to monitor pixels. So two images with different pixel dimensions would view as different sizes at 100% no matter what their resolution. So these two images with the same 2"x3" output dimension, viewed at 100% display as different sizes because their pixel dimensions are different:

                                                                         

                                                                        Screen Shot 2015-07-19 at 12.53.35 PM.png

                                                                        • 35. Re: Digital publishing - why not 72dpi?
                                                                          perrybrus Level 1

                                                                          Rob, seems to me that you are more occupied with winning a conversation against yourself than you are actually trying to solve an issue? I just wrapped this up two posts ago but you seem to be very occupied with yourself. Gives me the impression that you feel you lost this debate. Don't feel bad if it turned out that I was right all the way. I'm not claiming to be. I just conclude on the basis of this whole process.

                                                                           

                                                                          Both the images of Arnold are dropped into the two documents with at a size of 450x337px at 72ppi. The two images are copies. I have shown you the info palette from both PS and ID. You replied :"To maintain the percentage relationship the pasted image would have to be up sampled to 300ppi., which would create quality problems." What are you trying to prove? The images are at identical size and they prove my point. I made those documents for you to see that 72ppi images will appear smaller in a 300ppi document than it will in a 72ppi document. Haven't you read anything?

                                                                           

                                                                          Feels like this is turning into an interrogation where your main goal is to play ball with the intent to win back something you lost during this process. You are making a monster out of this. I am not going to reply to any of your further posts on this topic Rob. As I said, its been established that ID cannot produce documents with separate document resolutions like PS are able to. If you wanna stick around to twist words and find your own little pronunciation to this conclusion then fine. Feel free. Again, thanks for sharing and taking an interest in the topic (I hope)