PDF with high resolution image huge file size

Hello. I am trying to export PDFs of drawings with a high resolution image covering almost an entire A1. I realize of course that the file will be very large but it is much larger than I feel it should, and there are also some discrepancies.

The original image is around 100 MB, but only about half is visible in the viewport, so the PDF should be around 50 MB if there is no compression (only negligible amounts of text and lines besides the image), however if I plot it to a PDF using Adobe PDF, setting the resolution to 300 dpi and medium JPEG compression the resulting file is 150 MB. If I choose 72 dpi and low JPEG compression the file looks very bad and compressed but is still around 40 MB in size. This is far too large considering the amount of compression visible in the image, it looks like a 500 KB file tops.

However if I use the DWG to PDF printer instead of the Adobe PDF I can get a very good looking file at around 2,5 MB. Very suitable for printing, but the compression shows if you look up close in the computer (which is a requirement for these files). The odd thing here is that it makes no difference what resolution I set it to, 150 DPI to 1200 DPI creates the same looking file at exactly the same size. I'd like to be able to create a 2,5 MB file to email and a very high quality file for archivation, but not 150 MB large.

Another odd thing is that if I print another file but with the same type of image (a different facade) with 1200 DPI I get a very high quality file of 40 MB, but if I repeat the exact steps and settings for the first file I end up with a 150 MB file. Of course some differences in the image would account for some of this, but not nearly of this magnitude. I deleting everything from the large file and copying in the content from the small file, and successfully printed a 40 MB file again, so there doesn't seem to be some setting or bug in the file I am printing from, rather something in the original file with the image that I have Xref'ed.

Does anyone have any thoughts on this? Or some suggestions as to how I would go about creating a very high quality file that doesn't bloat up way more than the original image? A 40 MB file is great considering the images are huge, but I can't get this result consistently.

What is the specific purpose behind creating a PDF file versus some other type?

What is the specific purpose behind creating a PDF file versus some other type?

The client requests PDF files for archiving as well as for print and email. These files with the images are part of a larger set with line drawings etc, so they follow the same layout and style and in some cases they overlap. Were it just an image I would save if as a TIFF or something along those lines but they do include some lines and text that need to be in PDF (or something else if you have any suggestions?).

I may add to the first post concerning the discrepancies between the two files that the source images were both around 100 MB, so it seems AutoCAD or Adobe PDF does something to the first, large image, that it doesn't do to the second.

Have you had good experience with compressing images using the Adobe PDF from within AutoCAD? I've used it a lot in InDesign with pleasing results but now it just seems to give me way to large files with way to bad quality.

Thank you for the fast reply!

What is the original image type?

Have you tried just printing the image to PDF and check the size?

Thank you for answering my question. I do not know how you can improve the quality of your PDFs and at the same time keep the file size from becoming bloated.

It may be that the LARGE pdf contains the AutoCad layer information, and the other smaller ones do not.

When plotting click on the properties button beside the DWG to PDF plotter, go to the device and document settingd tab, custom properties, hit the customs properties button and ensure the "Raster Image Resolution" is set to a suitable quality. Playing around with the settings here I was able to increase and decrease the quality of the images I was plotting with the DWG to PDF plotter.

Do you have access to the original image? If so you should look into editing the image before putting it into your drawing. If you have photoshop try that or any other image editing program. You may be able to decrease the image file size without to big a hit to your resolution. There are some programs that can store a high resolution image in a certain way that reduces the file size but I'm not sure how to get my hands on a program like that or if it can even work with autocad. When it comes to image files the only thing that matters on size is pixel count. The more pixels the higher the resolution.

I hope you enjoy walls of texts... I've been trying to troubleshoot this as best I can.

What is the original image type?

 

 

Have you tried just printing the image to PDF and check the size?

The original image is a JPEG that has been Xref'd into a DWG file that in turn has been Xref'd into another DWG file with all the layout etc. Same with both files.

I tried printing the images to a A1 PDF with the Adobe PDF from withing Photoshop, with the High quality-setting. The result is two files with high quality and around 11 MB each. This is more what I would expect in terms of quality versus size. However if I print the same files (plus some text and layout lines) from within Photoshop i end up with files that are 100 MB large, but similar quality.

There are more than 1 image in the original DWG though, but those other as well as parts of the image I am talking about is cropped by the viewport. Could it be that AutoCAD does not crop properly, and somehow includes the rest of the image and the other images in the PDF as well?

I tried printing just a single image in a new document in AutoCAD, and the file size was around 13 MB.

as well as cropping it very much and comparing the file size to an uncropped image and the cropped file was much, much smaller. So it seems AutoCAD do handle cropping by viewports well.

I then tried unloading all images except one (this is the original, too large file) and printing, resulting in a 100 MB file again. So it does indeed look like AutoCAD doesn't include images that are outside of view.

It's strange however that AutoCAD managed to print just the image Xref'd into a document without bloating the file size. I tried clean up the file from everything except the image, erasing the layout-lines and freezing all the layers in the Xref'd file, and voila I managed to get a 30 MB file. However if I turned on any other layer, even just one with some small scribbles on it the size went back up to 100 MB. No difference if the layer belonged to the Xref or to the current file.

I am beginning to think this might just be a bug. I get the same result on two different computers using AutoCAD 2010 LT and AutoCAD 2012 though...

Thank you for answering my question. I do not know how you can improve the quality of your PDFs and at the same time keep the file size from becoming bloated.

Thank you for the reply, anyway!

It may be that the LARGE pdf contains the AutoCad layer information, and the other smaller ones do not.

I thought something like that would be the case but in Acrobat Pro when saving as Optimized PDF you can use the Audit space usage-function and it shows that 99% of the file size is an image.

When plotting click on the properties button beside the DWG to PDF plotter, go to the device and document settingd tab, custom properties, hit the customs properties button and ensure the "Raster Image Resolution" is set to a suitable quality. Playing around with the settings here I was able to increase and decrease the quality of the images I was plotting with the DWG to PDF plotter.

I've done this and tried to explain it earlier, but the result was the same no matter what settins I used, which is very odd, otherwise this method would be just what I am looking for. Could there be some plot setting that is somehow overriding it?

Do you have access to the original image? If so you should look into editing the image before putting it into your drawing. If you have photoshop try that or any other image editing program. You may be able to decrease the image file size without to big a hit to your resolution. There are some programs that can store a high resolution image in a certain way that reduces the file size but I'm not sure how to get my hands on a program like that or if it can even work with autocad. When it comes to image files the only thing that matters on size is pixel count. The more pixels the higher the resolution.

I wish I could do this, but the file is being used by multiple other files both for working on and for printing/saving. Worst case scenario would be to have to make a separate file and manually compress it to suit the specific need (even thought I think this would yield the best result). I was hoping to be able to reap these benefits from within AutoCAD and the PDF plotter alone.

Thank you all for the replies. I am starting to feel like I've exhausted my ideas for troubleshooting, so any further input would be greatly appreciated.

I've done this and tried to explain it earlier, but the result was the same no matter what settins I used, which is very odd, otherwise this method would be just what I am looking for. Could there be some plot setting that is somehow overriding it?

Look at the RASTERDPI system variable. I am not sure if it effect the plotting of raster images or not.

Look at the RASTERDPI system variable. I am not sure if it effect the plotting of raster images or not.

I tried changing that from 300 (inital) to 100, and 1200, and 2400 but it makes no difference. Can I ask you if you are able to get different results by changing the

DWG to PDF>Properties>Custom properties>Raster image resolution ?

I thought something like that would be the case but in Acrobat Pro when saving as Optimized PDF you can use the Audit space usage-function and it shows that 99% of the file size is an image.

Have you tried downsampling the images within Acrobat Pro (Advanced/PDF Optimizer)?

Perhaps you would be better off doing this the other way round.

Instead of using Autocad to create the PDF, would it not be easier to import your CAD file into a Graphics package such as Illustrator or Photoshop, where you would have much better control of the PDF creation process?

Just a thought.

It wouldn't affect your original file and your client would have the file in a format of his choosing.

Dahzee

That would be one solution, but too much of a hassle for this projects, loads of files that get updated and different people need to be able to create PDFs. I guess this will remain an unsolved mystery...

:shock::shock:

Boom! Solved it! So, it turns out if your viewport is a converted polyline, and not a "pure" viewport, a "clipped" viewport... and have a high resolution raster image xref'd into the document the Adobe PDF printer creates huge files! Such a relief to have finally solved it. I tried creating a clipped viewport of the same view in one of the documents that was working fine and voila: 100 MB file! Then I tried creating a "normal" viewport of the same view in one of the non-working documens, and voila again: 8 MB file!

So on the off chance anybody else has this issue, that is the solution. Feels good to revive this thread with a victory. Thank you all for the help.

Wow, that's huge for just the shape of a viewport.

Does the same happen when using the DWGtoPDf.pc3 from AutoCAD?