PDF File Size Too Large After Adding Images — Any Compression Tips?

[Dr. Mobile Profix_Gra5294]

Post Content:
Hi everyone,

I work on creating downloadable guides and technical reports for our solar energy website — https://nedes.us/ — and we often use Adobe Acrobat Pro to combine multiple charts, installation diagrams, and product images into one PDF.

The problem is, even after optimizing images before import, the final PDF sometimes ends up being over 50 MB. I’ve tried:

• “Save as Optimized PDF”

• Using Reduce File Size under Tools

• Changing image downsampling to 150 dpi

But the results aren’t always consistent.

Could anyone recommend best compression settings or workflows for PDFs that contain lots of visuals but need to stay under 20 MB? I’d also love to know if Acrobat handles embedded vector graphics differently from JPEG/PNG images.

Thanks for your help!
— Hamza

[gary_sc]

The one thing that often comes up is that people do not resize their images to the size they need. Yes, changing resolution is good, but the total number of pixels in width and height also makes a difference.

Consider: if you have an image that is 4000 pixels wide by 3000 pixels tall (12,000,000 megapixels) and you take that image and place it in a section on a page that is 4" x 3", it's still 12,000,000 megapixels because you did not resize the image, you only crammed it into a smaller space. 

Now, take that image and resize it to 4" (x 150= 600 pixels) x 3" (x 150=350 pixels) or 600 x 350 =210,000 pixels. That's 0.0175 of the size of the original.

Another way to think about this is if you halve the size of the image, you decrease its storage size by 3/4.

If you have Photoshop and need me to explain how to resize an image, I'll be glad to show you.

Oh, and yes; vector graphics can be considerably smaller than jpg images. As far as jpg versus png, think of it this way: jpg images of people and trees will be of much better quality than jpg images of text and objects. But, a png image of text and objects will be much better looking and smaller than if they were jpg images. In other words, use the image format best suited to the type of image. It may sound complicated, but it's really not once you understand the basics.