simon bd Posted January 27 Posted January 27 Hi, I have a graphic novel in Publisher that I want to export as a PDF. I don’t want the PDF to be too heavy, and I don’t need perfect quality. Content is grayscale art (from Designer), native resolution is 400. So I export with: Resolution = (400) and Quality = 60, and I get a 316 MB file. Quality is great, but I’d like a smaller file. So I export with: Resolution = (400) and Quality = 40, and I get a 316 MB file. Same apparent quality. So I export with: Resolution = 200 and Quality = 60, and I get a 316 MB file. Same apparent quality. I don’t get it. I can never seem to control these settings with expected results. Maybe I’m not doing it the right way? Thanks for your help Simon Quote
Staff NathanC Posted January 28 Staff Posted January 28 Hi @simon bd, I'd recommend checking your placed image's DPI values against your PDF export settings; the JPEG Compression Quality % will affect image layers that are downsampled/flattened on export, which is actioned based on your 'Downsample Images - Above X DPI' setting, which for most presets is set to downsample images above 375 DPI. They are flattened to your document (or custom) DPI value and are thereby affected by the JPEG compression quality. You'll therefore want to have the 'Downsample Images' setting enabled and perhaps consider changing the Above X DPI setting depending on your images. Quote
thomaso Posted January 28 Posted January 28 14 hours ago, simon bd said: I don’t want the PDF to be too heavy, and I don’t need perfect quality. Content is grayscale art (from Designer), native resolution is 400. (…) I don’t get it. I can never seem to control these settings with expected results. Maybe I’m not doing it the right way? What does "too" and "expected" result mean exactly to you? Do you expect a certain PDF file size? DPI: If you want a PDF for screen view only then the export settings can be different than for a print job. Grayscale: Grayscale can mean either 100% black only ('black and white', e.g. text) or 0-100% black ink or RGB with identical values for each channel or CMYK with empty CMY channels for instance. Each of them may result in a different export file size. – If you make sure to use a 'true' grayscale profile for export (≠D50) then the resulting PDF will have only the black ink channel and accordingly have a smaller file size than an 'grayscale' RGB file for instance (~33%). Page dimensions: You don't mention page dimension nor number of pages. Both influence the file size of an exported PDF. Reducing page dimensions by 50% (e.g. A4 -> A5) reduces the page area down to 25% and may result in a export file size of about 25%. 14 hours ago, simon bd said: Same apparent quality. In your listed comparisons you need to view each resulting PDF at 100% zoom level (pixel size, not page size) to make a valid judgment about the visual quality. If you compare a 400 DPI export with a 200 DPI export they appear in quite different sizes on screen when viewed at 100% pixel size and a comparison or judgement like "same appearance" seems to be not useful or at least ambiguous. Quote macOS 10.14.6 | MacBookPro Retina 15" | Eizo 27" | Affinity V1
simon bd Posted January 28 Author Posted January 28 3 hours ago, NathanC said: You'll therefore want to have the 'Downsample Images' setting enabled and perhaps consider changing the Above X DPI setting depending on your images. Thanks for your reply @NathanC. All my imported images have a 400 dpi resolution. There is nothing else in the Publisher file except page numbers. Now when I choose a PDF resolution of 200 dpi, with Downsample Images above 375 (which should apply to all my 400 dpi images), I get the exact same result in size & quality. Shouldn’t the resulting PDF be much smaller and have less quality, with all the original 400 dpi images reduced to 200? That’s what I don’t understand. Quote
simon bd Posted January 28 Author Posted January 28 Thanks, @thomaso. I’m comparing results using different PDF settings when exporting the SAME original Publisher file. Of course I would get different results with a different number of pages or a different colour world. Quote
simon bd Posted January 28 Author Posted January 28 OK, I think I figured it out. There’s a checkbox that says “Use the file’s resolution”. It remains checked even if you change the desired PDF resolution. This would explain why the resulting PDF is always the same. You have to manually uncheck this option for the new resolution settings to take effect. Not sure what the difference is between these two options though: Resample images higher than XXX dpi Resampling: beyond XXX dpi (I’m translating from French; English wording may differ. Please see image.) Quote
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