Need to shrink InDesign file by over 200mb

Report · Sep 06, 2023

Hello, I have made a book in InDesign that I need to be able to export as a PDF for an e-book and use for printing purposes.

I have a 300 page InDesign file with over 1500 linked .ai illustrations- note these are 2D flat illustrations and not super detailed images. The InDesign file is 245MB and when exported to PDF is over 100MB. I need to get it to less than 20MB when exported to PDF and when compressed can only get it as small as 50MB.

I have been searching and trying things for days- I have played with the compression when exporting, cleaned up all unused objects, and made sure everything is linked and not embedded. Is the only other thing for me to do to literally go through each .ai file and make it smaller? And if so does anyone have any recommendations on what size I should aim for? My files range from 100-700 kb per image. I looked into turning all of them into .svg files which would make them SIGNIFICANTLY smaller but cannot find if there are downsides to this. I know I can't do this for detailed photos but all of my elements I linked in my book are 2D illustrations so would this be fine to do?

I appreciate anyones insight and expertise on this!

Report · Sep 06, 2023

This is strictly a question for the Acrobat forum. Your title says you need to shrink InDesign File but your text that it is the PDF that needs slimming.

What PDF setting are you using? What is your transparency flattening settings? (https://helpx.adobe.com/indesign/using/flattening-transparent-artwork.html)
Detailed vetors can be hard to downsize, and sometimes a bitmap may be smaller. In Adobe Acrobat there is an audit tool so that you can see what is taking memory. Keeping text as text rather than outlining, excluding fonts and/or makng sure that fonts are only included once (by not having the fonst included in the AI files may be one place to look). Would almost need to see the kind of file and a screenshot of the Audit from Acrobat.

Start by reading up on https://helpx.adobe.com/acrobat/using/optimizing-pdfs-acrobat-pro.html

Report · Sep 06, 2023

Thank you so much for your response. This is my first big project using InDesign and there is definitely a lot I need to learn. I figured the only way to do this was to focus on shrinking the InDesign file size itself rather than focusing on the PDF file since the PDF file is only large because my InDesign file is large. I figured I just set up my InDesgin file poorly and my images I linked were too large. Thank you SO much for showing me the PDF audit tool! I had no idea this was an option. I put a screenshot of my audit file below and it looks like about 50% of the space is due to content streams and document overhead. I'm going to read the link you sent me and look into how I can optimize it more- appreciate your help so much. Do you have any recommendations based on the audit report?

Report · Sep 06, 2023

An Indesign file can be bigger than the PDF since the preciews of placed files may be different than the files themselves. Content streams may be vector graphics. (If you delete images and then export you would know how much you can save, you can text on a copy of couple of pages to see what happens. Compare with image and without image) .

could you show a sample of a typical page with image? Is it line art? Technical illustration or rich graphics with transparency and effects? Do you also have backgrounds and textures?

Try saving with "smallest file size" PDF setting… and even if it isn't what you want comparing different export settings in size and file usage may help to understand where you can save file size.
(When printing it is not unusual to get PDF files that are 10x as large as your file without having production problems)

Report · Sep 06, 2023

I tested on a few pages by changing my linked .ai files to .svg files and it saved about 40 mb. I have also tested simpliying each .ai image so it doesn't include so many paths but this didn't shrink it nearly as much as saving it as an SVG file did.

On each page is a heading and then organized into different sections with the amount of illustrations varying per page. All illustrations are line art with color but are all 2d drawings so not very complex. Some are extremely simple drawings such as a simple shape, and others are more detailed diagram drawings and some include small amounts of transparent elements. I have about 10 section pages to split chapters in which the entire page is a pattern I created and these are larger elements, about 1-2 mb per page. Hopefully that makes sense.

I just tried saving it as "smallest file size" and didn't do much, still at 102 mb so saved maybe 5 mb. I'm thinking I maybe have to go into each .ai file then to individually shrink each illustration.

I did just test saving a .ai file as a jpg and makes it just as small as when I save it as an SVG- literally went from 250 kb to 20 kb- so I'm assuming doing that for all 1500 images would make a substantial difference in my Indesign file size if about 40% is due to vector, right?

Do you advise using jpg instead of SVG in InDesign if the goal is to save it as a PDF for an e-book? The jpg is much lower quality than the SVG file which why I get so confused why most people recommend that instead of an SVG.

Report · Sep 06, 2023

Sometimes vectors may take more space than bitmap - if they are complicated.

Shadows / transparency may create extra bitmaps.

I think you can convert your vectors to bitmaps - at least those more complicated and with shadows / transparency - as long as users won't need to zoom in - too much.

Report · Sep 07, 2023

1500 x 20kb is still 30MB...

I think going for bitmaps - preferably b/w and 1:1 pixel size...

Report · Sep 06, 2023

About SVGs, you can make illustrator SVG smaller but it may not help bring PDF size down. SVG works by not having as many decimals. but that rounding off may simplify or distort paths without gaining much file compression. Seeing the kind of image would help give advice but generally if you have few colurs and crisp lines PNG or TIF and if tehre are many gradients then exporting a copy as JPG to place for digital file may be a way to slim the file (with a certain loss of quality hlere resolution vs quality will also vary depending on style of artwork).

Report · Sep 07, 2023

I have had quite good experiences with online tools, where I uploaded my exported Pdf and then it was automatically reduced in size. The quality has remained the same and the images were not pixelated as if I had exported it from ID as an e-book. However, the size was significantly smaller than the e-book Pdf from Indesign!

Report · Sep 07, 2023

What did you do to do this? I have looked up endless amounts of PDF compressors and have only been able to get it from 110 mb to 50 mb when I need it less than 20 mb.

Report · Sep 07, 2023

If you are sending this out for print, my question is "who cares how big the file is, as long as it's reasonable?"

Spoiler alert: 200MB is reasonable for a graphic heavy file.

Report · Sep 07, 2023

It's not the size for print I am focusing on, it is the sizing for digital use- where I need to upload it has a limit of 20mb which is why I am trying to make it smaller. I have already been using a workaround by uploading it to Google Drive and giving my customers a PDF with a link to the Google Drive, but recieve multiple messages everyday for technical help, so my thought is that it would be a better customer experience if I could just upload it directly.

Report · Sep 07, 2023

20MB / 300 pages is less than 70kB / page...

A lot for b/w bitmaps - but not a lot for RGB...

Should be enough for simple vectors - but without shadows and transparencies that will create extra bitmaps.

1500 .ai files is a lot of vectors... and I'm not talking about only pure vector information - but all other extra info - "header" and "footer" of the linked file that needs to be embedded.

Report · Sep 07, 2023

Where are uploading it to? AFAIC, you're focusing on the wrong thing. In 2023 20MB is nothing. Find a different service to host it.

I've uploaded PDFs that are way larger than that for display/viewing on client websites.

Report · Sep 12, 2023

Hi @agf349,

Thank you for reaching out. In addition to the suggestions shared above, you can also check the suggestions shared in this similar discussion and feel free to reach out if you need further assistance.

Thanks

Rishabh