Acrobat image compression

steppy

Well-known member
My pdf has images without compression.

When I "save as" (NOT save optimized or reduced size) my images have .zip compression.

Is there a setting that to configure so that I don't have compression?

stephen

Using Acrobat DC version 2021.005.20058
 

steppy

Well-known member
ZIP compression is loss-less, why is it objectionable for you?
Can't say ZIP compression is "objectionable" and if we wanted compression, that's what we'd choose.

File size is less of a consideration and we're looking to avoid any compression/decompression processing overhead. We've got plenty of space and very old slow RIPs.

Perhaps its only minimally significant, but, we'll take what we can get. :>}
 

Joe

Well-known member
I think the only way is to create an optimized PDF setting and change image compression to 'use existing', in your case none, and then turn off all other optimization options. Then Save as Optimized PDF using the settings you created.
 

Dov Isaacs

Well-known member
@steppy ,

Of course you know that if your PDF file is any version beyond PDF 1.5, there in fact lossless ZIP compression applied to your object streams within your PDF file. Those object streams include but are not limited to all your text and vector content.

Unless your systems and/or RIPs are running on ancient platforms from well over a decade ago, the overhead of decompressing ZIP compression is truly minimal. (BTW, all current Microsoft Office .docx, .xlsx, and .pptx files are in fact ZIP files!)

- Dov
 

steppy

Well-known member
@steppy ,

Of course you know that if your PDF file is any version beyond PDF 1.5, there in fact lossless ZIP compression applied to your object streams within your PDF file. Those object streams include but are not limited to all your text and vector content.

Unless your systems and/or RIPs are running on ancient platforms from well over a decade ago, the overhead of decompressing ZIP compression is truly minimal. (BTW, all current Microsoft Office .docx, .xlsx, and .pptx files are in fact ZIP files!)

- Dov
Dov:

Thanks for your reply; been awhile and hope all is well.

Of course I suspected, but in truth, didn't "know" the ZIP compression was always applied. I think this does explain that my PDF made with no compression (see settings attached) does NOT have compressed images, but, as soon as the file is resaved, the images have ZIP compression applied.

Embarrassing to say, our RIPs are over a decade with a small difference in RIP time when files are not compressed.

I've tried some optimized save options that still result in ZIP'ed images. Is there and optimized save setting that will not ZIP images?

stephen
 

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Joe

Well-known member
Yes change your setting to Compression: Retain Existing. At least that worked on the test file I tried it on.

FYI your image above is not a screen shot of the Acrobat PDF Optimizer settings. Those are your PDF export settings. The PDF Optimizer settings don't even have a Compression: None setting. It only has JPEG, Zip, or Retain Existing choices.
 

steppy

Well-known member
Joe:

Thanks for the ideas!

Screen shot was only intended to show settings that do NOT give me ZIP compression out of InDesign.

In any instance when we save PDF made with these settings, we end up with ZIP'ed images.

I've tried Optimized save: Images>Compression>Retain existing

Also tried: Clean up>leave compression unchanged

Both still delivered ZiP"ed images.

Next tried: Clean up>leave compression unchanged AND unchecked "Use Flate to encode streams that are not encoded".
This saved file without ZIP'ed images.

stephen

probably spent more time testing than we'll save at the RIPs in the next 6 months :>}
 

chriscozi

Well-known member
Next tried: Clean up>leave compression unchanged AND unchecked "Use Flate to encode streams that are not encoded".
Hmmm. Something tickling me about 'Flate encoding' . . . . yes - this concerns multiple issues regarding multiple streams of data.
You really DO want 'Flate' because you may/will face serious file corruption issues down the road.
I know this from personal unfortunate experience.
This is also, if I remember correctly, a reason tif file structures are deprecated in modern graphics apps where they used to be more the norm. (If you can compress lossless, and you have to compress, why do you need tif?)
Anyone else remember their history of issues ???
 

Joe

Well-known member
There are uncompressed tiff files and there are tiff files that use LZW compression. The only thing we use tiff files for nowadays are one-bit tiff files using LZW compression for making plates.
 

Joe

Well-known member
Joe:

Thanks for the ideas!

Screen shot was only intended to show settings that do NOT give me ZIP compression out of InDesign.

In any instance when we save PDF made with these settings, we end up with ZIP'ed images.

I've tried Optimized save: Images>Compression>Retain existing

Also tried: Clean up>leave compression unchanged

Both still delivered ZiP"ed images.

Next tried: Clean up>leave compression unchanged AND unchecked "Use Flate to encode streams that are not encoded".
This saved file without ZIP'ed images.

stephen

probably spent more time testing than we'll save at the RIPs in the next 6 months :>}

In my test I had a PDF with an image in it that was not compressed. I used the PDF optimized setting for Compression: Retain Existing and I saved that PDF out of Acrobat DC to a new PDF. The uncompressed image came out still uncompressed.

As far as Indesign I believe if you place a PDF into InDesign and that PDF has image compression then the new PDF generated will keep that existing compression. In other words it won't decompress a compressed image from that original PDF. I'm not certain about JPEG but it might be if you place a JPEG into InDesign that was previously saved using image compression than it might retain that compression in the new PDF. Like I said though I'm not certain on that point and haven't tested it.

I do believe you are over-estimating any benefit you might see using no compression. Using no compression will result in a larger file size which probably means more processing and probably negates any benefit not having to uncompress any images.

And btw Adobe's PDF settings default to using JPEG compression. Even in PDF X-4 PDF settings which is baffling. Do yourself a favor and never use JPEG compression. Always use ZIP compression.
 

steppy

Well-known member
Hmmm. Something tickling me about 'Flate encoding' . . . . yes - this concerns multiple issues regarding multiple streams of data.
You really DO want 'Flate' because you may/will face serious file corruption issues down the road.
chriscozi:

Thanks for chiming in.

Never having disabled Flate before I can't say that I've had any issues associated with or without it. What kind of issues did you experience?
 

chriscozi

Well-known member
Never having disabled Flate before I can't say that I've had any issues associated with or without it. What kind of issues did you experience?
If memory serves:
Randomly corrupted files of all sizes shapes and descriptions.
Problem:
It seems that modern OS's?, processors?, and/or file storage systems? expect optimized file data.
So when files are made of separate and different data streams (think vector info and bitmap info to start simply) the files get stored as one big lump of data.
Now we are modern!
We save space!
But wait!
I have a real big bunch of zero's or one's in a row.
We'll save space and compress that data stream.
Oops.
That was just a portion of the file and when the file gets read back out it can fail because what part of what data stream was it, again? and what did the storage savings do to the data?
Answer:
So today we have file structures, built by each/most modern applications, that AUTOMATICALLY compress the file streams INDIVIDUALLY(?) internal to each file, to avoid just this type of problem.
 

Dov Isaacs

Well-known member
… And btw Adobe's PDF settings default to using JPEG compression. Even in PDF X-4 PDF settings which is baffling. Do yourself a favor and never use JPEG compression. Always use ZIP compression.

That really is not quite true! The default image compression for PDF/X-4 (and for that matter most of the joboptions for PDF export are as follows:

2021-07-20_13-58-44.png


Automatic (JPEG) is not the same as JPEG. You ask “what's the difference?” Good question!

JPEG results in all images being JPEG-compressed with the image quality specified.

On the other hand, if Automatic (JPEG) is specified, the image is examined and if the image is really simple vector or text content in raster format, lossless ZIP compression is used in lieu of JPEG compression resulting in higher quality and no JPEG compression imaging artifacts! And if the resultant image has no more than 256 distinct colorants, indexed color is used to save space.

Note that there is a similar set of settings for you JPEG 2000 fans, Automatic (JPEG 2000) versus JPEG 2000 compression with similar characteristics.

Note - to put to rest a long-lingering misconception by industry Luddites, there is absolutely no loss of image quality using ZIP (otherwise referred to as flate compression) in a PDF file or for that matter in TIFF files. (Likewise, LZW compression, not typically available with current PDF tools but commonly used in TIFF files, maintains full image fidelity although typically with not as much compression advantage that ZIP-compression provides!)

- Dov (no longer @ Adobe!)
 

Joe

Well-known member
That really is not quite true! The default image compression for PDF/X-4 (and for that matter most of the joboptions for PDF export are as follows:

View attachment 290819

Automatic (JPEG) is not the same as JPEG. You ask “what's the difference?” Good question!

JPEG results in all images being JPEG-compressed with the image quality specified.

On the other hand, if Automatic (JPEG) is specified, the image is examined and if the image is really simple vector or text content in raster format, lossless ZIP compression is used in lieu of JPEG compression resulting in higher quality and no JPEG compression imaging artifacts! And if the resultant image has no more than 256 distinct colorants, indexed color is used to save space.

Note that there is a similar set of settings for you JPEG 2000 fans, Automatic (JPEG 2000) versus JPEG 2000 compression with similar characteristics.

Note - to put to rest a long-lingering misconception by industry Luddites, there is absolutely no loss of image quality using ZIP (otherwise referred to as flate compression) in a PDF file or for that matter in TIFF files. (Likewise, LZW compression, not typically available with current PDF tools but commonly used in TIFF files, maintains full image fidelity although typically with not as much compression advantage that ZIP-compression provides!)

- Dov (no longer @ Adobe!)

But if it is a photographic image it will use JPEG compression, correct. Not cool Adobe...not cool at all. And don't get me started on "text content in raster format". Ugh.
 

Dov Isaacs

Well-known member
But if it is a photographic image it will use JPEG compression, correct. Not cool Adobe...not cool at all. And don't get me started on "text content in raster format". Ugh.

For the vast majority of photographic images that are properly focused (and sharp) and not ridiculously cropped / magnified and then artificially up-rezzed, maximum quality JPEG compression in the PDF file used for printing typically yields perfectly acceptable results for the vast majority of printing and display situations. Note that I would absolutely never advocate storage of digital master images that are subject to editing (and possibly multiple stages and rounds of editing) to be stored in JPEG or even JPEG 2000 (other than lossless JPEG 2000) formats. For that purpose, personally, I typically use ZIP-compressed TIFF with ICC color-managed 16 bits colorant per pixel storage coming out of Camera Raw! (Typical RAW images from professional digital cameras are natively and typically 10 to 12 bits colorant per pixel. Conversion to 8 bits colorant per pixel is in fact lossy.)

Adobe does not require any use of JPEG compression. You are quite free (and encouraged) to make your own joboptions that meet your particular needs or religious beliefs. That having been said, general industry experience is that the default Automatic (JPEG) setting in fact does meet the photographic image quality requirements of the vast majority of graphic arts customers. Is there some lossiness with even maximum quality JPEG compression of photographic images? Of course there is! But most customers are not viewing such images and comparing them with originals with very high-powered loupes! And that is exactly why the default settings with regards to compression are as they are!

I certainly don't disagree with regards to text or vector content in raster format. The sad news is that all too often such content (including, ugggh, logos) is provided to graphic artists who have no choice in the matter. The only common situation in which graphic arts applications themselves force text and vector graphics into raster formats is when users improperly flatten transparency when creating a PDF file. That is exactly why knowledgeable industry experts advise use of PDF/X-4 with full ICC color management and without any transparency flattening. Issues of transparency are best handled by the RIP during final rendering!

- Dov
 
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abc

Well-known member
If your rips are over a decade old, did you ever look at the speed improvement if you upgraded?
Seems you have to jump through hoops to get things to work, and this is only going to get worse as PDF 2.0 and PDF/X-6 come on stream.
Maybe you can build an ROI for an upgrade?
 

Joe

Well-known member
For the vast majority of photographic images that are properly focused (and sharp) and not ridiculously cropped / magnified and then artificially up-rezzed, maximum quality JPEG compression in the PDF file used for printing typically yields perfectly acceptable results for the vast majority of printing and display situations. Note that I would absolutely never advocate storage of digital master images that are subject to editing (and possibly multiple stages and rounds of editing) to be stored in JPEG or even JPEG 2000 (other than lossless JPEG 2000) formats. For that purpose, personally, I typically use ZIP-compressed TIFF with ICC color-managed 16 bits colorant per pixel storage coming out of Camera Raw! (Typical RAW images from professional digital cameras are natively and typically 10 to 12 bits colorant per pixel. Conversion to 8 bits colorant per pixel is in fact lossy.)

Adobe does not require any use of JPEG compression. You are quite free (and encouraged) to make your own joboptions that meet your particular needs or religious beliefs. That having been said, general industry experience is that the default Automatic (JPEG) setting in fact does meet the photographic image quality requirements of the vast majority of graphic arts customers. Is there some lossiness with even maximum quality JPEG compression of photographic images? Of course there is! But most customers are not viewing such images and comparing them with originals with very high-powered loupes! And that is exactly why the default settings with regards to compression are as they are!

I certainly don't disagree with regards to text or vector content in raster format. The sad news is that all too often such content (including, ugggh, logos) is provided to graphic artists who have no choice in the matter. The only common situation in which graphic arts applications themselves force text and vector graphics into raster formats is when users improperly flatten transparency when creating a PDF file. That is exactly why knowledgeable industry experts advise use of PDF/X-4 with full ICC color management and without any transparency flattening. Issues of transparency are best handled by the RIP during final rendering!

- Dov

Welcome to printing. Almost all images in the work we have are "ridiculously cropped / magnified and then artificially up-rezzed". Almost all print customers receive perfectly fine PDF ads and proceed to open them in Photoshop at 72 dpi, RGB, and save them as jpeg with max compression because 20 years ago someone told them PDF's were not good at the time plus they can get then get 200 images on their floppy disks. Which also converts all black text to 4 color black because they know nothing about color management. And also they want to send version 1.3 pdf's because at that same time 20 years ago people couldn't get PDF's through their Flintsones RIP if they had transparency. So the goto fix back then was pdf 1.3. Here are a couple of screenshots of images our customers provide thanks to the magic of photoshop with its ability to murder PDF's.

Screen Shot 2021-07-21 at 7.50.50 AM.png


Screen Shot 2021-07-21 at 7.52.03 AM.png
 

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