31 Replies Latest reply on Jul 24, 2015 9:25 AM by Minkawf

    Image size confusion

    Minkawf

      I have a jpg, 72 dpi, 1000 px by 800 px. I place it in an InDesign document by dragging the transparent pane where I want it and clicking once. This, I am told, will result in the image being placed at full size. Instead, the image is placed at exactly half size, 500 px by 400 px. This mystifies me. Also mystifying: when I manually resize the image to full size, it begins to pixelate. Any thoughts? It's happening with all my images, all of which are 72 dpi.

        • 1. Re: Image size confusion
          BobLevine MVP & Adobe Community Professional

          What transparent pane are you referring to? And what is intended output?

          • 2. Re: Image size confusion
            Minkawf Level 1

            I mean when you go file>place, click on the desired file, and a translucent thing with your image in it appears, that you can drag around in the document. Intended output is web. At least that what I designated when creating the document. My purpose is to export to pdf.

            • 3. Re: Image size confusion
              BobLevine MVP & Adobe Community Professional

              Then you shouldn't be using web or digital publishing or pixels.

               

              Go back to inches.

              • 4. Re: Image size confusion
                Minkawf Level 1

                I should say that when I manually resize the images to their correct size and export to pdf, the images, which are pixelated in the InDesign doc, are completely fine in the pdf.

                • 5. Re: Image size confusion
                  BobLevine MVP & Adobe Community Professional

                  Set the display performance to high quality.

                  • 6. Re: Image size confusion
                    Minkawf Level 1

                    Wow. How many inches should a pdf be? I have no idea. I figure my images are meant to look good on a computer screen, and their pixel size/dpi reflect that. So I want the document slightly bigger than the images, in pixels. Have no idea how that translates to inches.

                    • 7. Re: Image size confusion
                      BobLevine MVP & Adobe Community Professional

                      A letter size PDF is fine for on screen viewing.

                      • 8. Re: Image size confusion
                        Minkawf Level 1

                        The display performance setting really helps. Thanks!

                         

                        So you're saying I should make my intent "print", and choose letter size. What exactly do those width and height settings mean? "66p0", "51p0". Are they picas? Sorry, I'm new here.

                        • 9. Re: Image size confusion
                          BobLevine MVP & Adobe Community Professional

                          There’s a preset for letter size but InDesign defaults to picas. You can change that in your preferences.

                          • 10. Re: Image size confusion
                            Peter Spier Most Valuable Participant (Moderator)

                            Some additional information....

                             

                            When you drag the cursor while placing your images ID is going to scale the image to the size of the frame you drag. If you want 100% just click where you want the upper left corner.

                             

                            ID uses a 1:1 correspondence between pixels and points when designing for screen. A Postscript pica is 12 pts, and there are 6 of them per inch, so 72 points per inch. If you save your image at 72 ppi, you can divide the pixel measurements by 72 and that will tell you how any inches in each direction when placed at 100%.

                            • 11. Re: Image size confusion
                              Minkawf Level 1

                              Peter:  Thanks, I'll have to let that soak in. One q: are  "ppi" and "dpi" interchangeable terms in this discussion? I use Mac Preview and a bit of photoshop for working on images. I only deal with "dpi" in those programs, to my knowledge.

                              • 12. Re: Image size confusion
                                BobLevine MVP & Adobe Community Professional

                                They have, sadly, become interchangeable but they are not the same thing.

                                 

                                 

                                 

                                Image resolution is ppi. Printer resolution is dpi.

                                • 13. Re: Image size confusion
                                  Minkawf Level 1

                                  Thanks to both of you for your help. I'm working with the "print" image at letter size, though I changed the width a bit because I want my "pages" or image areas to be square. There still seems no rhyme or reason to what size the image is when placed. One image appears much smaller than its page, the next is too big to fit.  When I resize images, I have nothing to go on in determining if I'm going too big (past the image's true pixel size), since I know what the correct size should be in pixels only. But maybe Peter's advice will help me translate. At least with high quality perfomance setting, I should be able to see if I'm overscaling an image, because it will appear pixelated.



                                  • 14. Re: Image size confusion
                                    Minkawf Level 1

                                    Bob: that's what I thought re: ppi/dpi. But if I change the "dpi" in those programs, I will be affecting the image's onscreen resolution, correct? Even though dpi should really only relate to printing.

                                    • 15. Re: Image size confusion
                                      Peter Spier Most Valuable Participant (Moderator)

                                      Lots of people use the two terms (incorrectly) as synonyms (including Apple Preview). Images are made of pixels, so are measured in Pixels Per Inch (or per centimeter where folks use metric units). Printed material is composed of dots made by the printer, which has dot density it produces, Dots Per Inch (dpi). A printed pixel is typically composed of many printer dots.

                                      • 16. Re: Image size confusion
                                        Peter Spier Most Valuable Participant (Moderator)

                                        Image resolution only exists in physical output. Changing the resolution of an image in Photoshop or other editing program, as long as you don't resample, will not change the pixel dimensions. What will change is the size the image will be rendered on your page at 100% in ID.

                                        • 17. Re: Image size confusion
                                          Minkawf Level 1

                                          OK, thanks for that info.


                                          I'm starting to understand your explanation of the relation between inches and pixels at 72ppi. I think you've been using "pixels" and "points" interchangeably in this discussion. So ppi could mean pixels/inch or points/inch, and those are exactly the same thing, correct?

                                          • 18. Re: Image size confusion
                                            Peter Spier Most Valuable Participant (Moderator)

                                            As long as the image resolution is 72 ppi, then yes, in ID you can make that correspondence.

                                            • 19. Re: Image size confusion
                                              Test Screen Name Most Valuable Participant

                                              "So I want the document slightly bigger than the images, in pixels. Have no idea how that translates to inches."   A reasonable think, but quite wrong. PDFs are not measured in pixels at all, though obviously they have pixels in them when you include images. But the size of a PDF is always in inches. Since images are always placed at a size in InDesign, InDesign also has inches (or mm if you prefer).

                                               

                                              Pixel-based design is for web based HTML. Don't use it for PDFs.

                                               

                                              "There still seems no rhyme or reason to what size the image is when placed. One image appears much smaller than its page, the next is too big to fit. "

                                               

                                              It will be following strict rules exactly. It just isn't using your pixel size as you expect. (A reasonable expectation, bit never what InDesign has done, because it is a print-led tool not a web-led tool). You can calculate the exact size an image will place by simply using the size in pixels and the resolution. For instance, if an image has a resolution of 72 ppi and is 144 pixels wide, it will be 2 inches wide. If it has a resolution of 300 ppi and is 150 pixels wide, it will be half an inch wide. You can see these figures clearly in Photoshop's image size setup.

                                              • 20. Re: Image size confusion
                                                Minkawf Level 1

                                                Thanks for the explanation. I guess pdf's are weird? I mean they are meant to be displayed on a screen, which is measured in pixels. A 1000 px tall jpg, viewed at "actual size" in Apple Preview, fills about 9" of my 10 and a smidge" tall computer screen (1920 x 1080 px). And yet at 72ppi, 1000 px corresponds to 13.8" in Adobe world. So what does an "inch" tell us about something we're looking at on a screen? Nothing, I think. But as long as I make my 1000 px image about 13.8 in. in ID, things seem to work out well for the pdf, image-wise, which is the main thing.

                                                 

                                                I do still find that when I drag the 1000 px, 72 ppi image to the upper left of an ID page and click, it's coming out far smaller than the 13.8" I think it's supposed to be. I mean, I can manually resize, but I'm just not understanding these default image sizes I'm getting. Must be doing something wrong.

                                                • 21. Re: Image size confusion
                                                  Test Screen Name Most Valuable Participant

                                                  PDFs aren't really made for screen specifically. They are a kind of electronic paper. And as first designed, the screen viewing was very much a secondary thing. This has changed over time - more and more for screen only use - but they continue to be an inch-based idea. We're stuck with it! When you compare with a JPEG, it isn't comparing like for like. For example a PDF might contain only text - how many pixels should that be? Or it might contain a 300 ppi image next to a 72 ppi image...

                                                   

                                                  Anyway, I'd kind of expect a 72 ppi, 1000 px image to be about 13.8 inches too. But that's more an InDesign question. But once it's a PDF the size in inches doesn't change. The size on screen will change with zooming, with settings and with software used.

                                                  • 22. Re: Image size confusion
                                                    rob day Adobe Community Professional & MVP
                                                    So ppi could mean pixels/inch or points/inch, and those are exactly the same thing, correct?

                                                     

                                                    No, PPI is an image resolution measurement and always means pixels per inch. InDesign has a unit of measurement called pixels that happens to be defined as a static 1/72". So the output of a letter sized page can be measured as 612x792 pixels, or 8.5"(612/72) x 11"(792/72), or 215.9 mm x 279.4 mm, etc.

                                                     

                                                    When you place an image scaled at 100% its dimensions on the page are its printed output size at 100%. Image resolution isn't considered—a 1"x1" image could have any ppi resolution and it would always output at 1"x1" or, using InDesign's pixel units as a measure, 72x72 pixels.

                                                    • 23. Re: Image size confusion
                                                      rob day Adobe Community Professional & MVP

                                                      I do still find that when I drag the 1000 px, 72 ppi image to the upper left of an ID page and click, it's coming out far smaller than the 13.8" I think it's supposed to be. I mean, I can manually resize, but I'm just not understanding these default image sizes I'm getting. Must be doing something wrong.

                                                       

                                                      As Peter mentioned in #10 stop dragging—when you do that you are scaling the image. Just click and the image will be placed at 100%.

                                                       

                                                      Here I have a 1000x1000 pixel page, which is what my rulers are showing:

                                                       

                                                      1000.png

                                                       

                                                      If I click and don't drag the image gets placed at 100%. As you can see from the Transform panel the placed image's frame's dimension is 1000x1000 px. The image also happens to be 1000x1000 pixels at 72ppi so it fills the page exactly.

                                                       

                                                      Screen Shot 2015-07-23 at 6.33.37 PM.png

                                                       

                                                      If I set my rulers to inches I can see the image frame is 13.8889"x13.8889". If I print the page at 100% that is what the print area will measure

                                                       

                                                      Screen Shot 2015-07-23 at 6.34.00 PM.png

                                                       

                                                      If I place a version with a higher resolution (250ppi) that has no affect on the frame dimension at 100% because I didn't change the image's dimensions, just the resolution, which is showing in link info.

                                                       

                                                      Screen Shot 2015-07-23 at 6.47.32 PM.png

                                                      • 24. Re: Image size confusion
                                                        Minkawf Level 1

                                                        Thanks for the info.  It's fairly clear, and I was able to duplicate Rob's examples in my own doc.  I did find that it only worked when I planned out my doc size ahead of time to be slightly larger than the large image I placed. When the doc size was smaller than the placed image, the placed image was over-large and pixelated. Not just larger than the doc, but larger, and of worse quality, than the same image placed in a larger doc.


                                                        I'm still not quite able to reconcile the first statement below, from Rob, with the second one, from Peter:

                                                         

                                                        1. "If I place a version with a higher resolution (250ppi) that has no affect on the frame dimension at 100% because I didn't change the image's dimensions, just the resolution, which is showing in link info."


                                                        2. "Changing the resolution of an image in Photoshop or other editing program, as long as you don't resample, will not change the pixel dimensions. What will change is the size the image will be rendered on your page at 100% in ID. " (italics added).


                                                        I know that earlier I put together a pdf of large images, just using Acrobat, and had an image size problem that involved resolution. Though all the images were close in pixel size, one of them rendered much smaller than the others in my pdf. Looking into it, I found that the image that rendered smaller had a larger ppi value. It was 180 while the others were 72. When I created a new version of the image at 72ppi, the image sizes in the pdf I made were fairly consistent. This made sense to me, in that when I encountered the inconsistency, Acrobat was taking the same number of pixels and making them fit into a smaller space when the image was 180 ppi, as opposed to 72 ppi. I've seen this happen in other programs, I think. I thought InDesign worked that way, but now I'm not sure.

                                                        • 25. Re: Image size confusion
                                                          rob day Adobe Community Professional & MVP
                                                          as long as you don't resample

                                                          Look at Photoshop's Image Size dialog. There's a checkbox for Resample. With it unchecked the image output size changes when you change resolution:

                                                           

                                                          Screen Shot 2015-07-24 at 5.53.30 AM.png

                                                          Screen Shot 2015-07-24 at 5.53.45 AM.png

                                                          Note that the pixel dimensions are the same in both cases.

                                                           

                                                          With Resample checked the pixel dimension changes but the output dimensions do not. InDesign uses the Width and Height numbers when you place, it doesn't care what the pixel Dimensions are or what the Resolution is. If you are getting different dimensions on the page, the image or its frame are not scaled at 100%

                                                          Screen Shot 2015-07-24 at 5.54.28 AM.png

                                                          • 26. Re: Image size confusion
                                                            Test Screen Name Most Valuable Participant

                                                            I wonder if it will help to think this way. Inches first (design not quality). Pixels second (quality not design).

                                                             

                                                            InDesign is about making pages for printing. If you design an advert or magazine for printing you have in mind a layout and sizes. (You might not know the inches exactly, but you know things have a size in inches). You create a magazine page. Here is the text. Here the headline - perhaps an inch high. Here is a picture, there is another picture. You've made a printed page. The number of pixels in your photos doesn't affect the design in any way.

                                                             

                                                            Of course, the number of pixels in your photo affects the quality and the file size, and it is part of the designer's job to get the right balance of quality and (where relevant) file size.

                                                             

                                                            When you make a PDF from InDesign, there is a simple and exact connection of size and layout. So these are really very similar ideas: the PDF has inches, and the InDesign page has inches. (Yes, of course, things can be printed at different sizes, but the designer still has just one size they work to).

                                                             

                                                            So, pixels: quality detail. That's all. (Vital, but all).

                                                            • 27. Re: Image size confusion
                                                              Minkawf Level 1

                                                              Thanks. I should have said earlier that I'm making a very simple pdf portfolio (as required for a submission I'm making) of photographed paintings. It has almost no text other than a bit inputted into a text box. Other than that, its only job is to present the paintings on a screen advantageously (good size, good clarity). One painting per page, filling maybe 80% of the page, each image able to fill maybe 60-80% of a computer screen, without any sacrifice in image quality. Printing is not a concern. So my needs are probably not those of most InDesign users. My standard metric for "image size that presents paintings advantageously on most computer screens" is to go about 1000 px in the long direction, which is why I started there.

                                                               

                                                              I tried just combining files into a single pdf in Acrobat, but found that made a poor presentation. And the Acrobat pdf portfolio templates are really unappealing to me. Which is why I turned to InDesign.

                                                               

                                                              Despite all the confusion, I made a very satisfactory document with this process, and the forum responses were helpful, so thanks,

                                                              • 28. Re: Image size confusion
                                                                Test Screen Name Most Valuable Participant

                                                                Glad it all came together. Here's one more thing to think about. How will your document look on a phone?

                                                                • 29. Re: Image size confusion
                                                                  rob day Adobe Community Professional & MVP

                                                                  One thing to consider about PDF is the view scale in Acrobat is the same as InDesign. The 100% view is the print dimension and not the 1:1 image to monitor pixel ratio you get in Photoshop. So you are right if the user is on a common display (1024x768), and the layout view is set to fit width, an image with a 1000 pixel width will be OK. But what if the user wants to zoom in? Or they are on a larger display (a retina iPad is 2048x1536)?

                                                                   

                                                                  You can't really control how the end user displays a PDF, so it wouldn't hurt to set a higher pixel dimension, which would accommodate higher screen resolutions and zooming.

                                                                  • 30. Re: Image size confusion
                                                                    Minkawf Level 1

                                                                    I emailed it to myself and took a look on my phone. Was happy to see that it was mobile-optimized, formatted to my phone dimensions. No side scrolling or zooming out required. The only zooming required is a bit of zooming in to read some text on the last page (which has no images). The image quality is OK, certainly not terrific. Even though the images are small, they still seem a bit pixelated or something....made of choppy little fragments when you look close. But I've got a phone with android 2.3 something, so not exactly state of the art. Anyway, this is for a gallery to decide if they want to hang my stuff on its wall. I doubt they'll use a phone to look at it. Sure hope not.

                                                                    • 31. Re: Image size confusion
                                                                      Minkawf Level 1

                                                                      Rob: Good point, maybe I'll try working with images around 2000 px instead. Which would mean a document that can accommodate images around 27", I think.

                                                                      • 32. Re: Image size confusion
                                                                        rob day Adobe Community Professional & MVP

                                                                        With PDF you don't have to worry about the pixel dimension of the document–it's not like HTML in a browser, everything gets scaled by Acrobat to fit the viewer's chosen zoom level.

                                                                         

                                                                        So there's no reason why you can't setup the document to something like 10"x8", then place and scale your high res image accordingly. Here my document is 10"x8" with a 9"x7" image centered. Its pixel dimensions are 2700 x 2100 and they won't change as I scale the image—InDesign always resizes images and never resamples.

                                                                         

                                                                        Screen Shot 2015-07-24 at 11.36.12 AM.png

                                                                         

                                                                        So even if I scale the image down I still have 2700 x 2100 pixels showing in info:

                                                                         

                                                                        Screen Shot 2015-07-24 at 11.36.38 AM.png

                                                                         

                                                                        When I export to PDF the image pixel dimensions won't change unless I explicitly ask for a down sample in the export dialog. So over in Acrobat I can see the image is still 2700 pixels wide in my 8x10 document:

                                                                         

                                                                        Screen Shot 2015-07-24 at 11.40.35 AM.png

                                                                        • 33. Re: Image size confusion
                                                                          Minkawf Level 1

                                                                          Rob: Great, thanks for taking the time to explain that.