Compression and Quark 8.5

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Compression and Quark 8.5

Postby Ray200 » 22 Mar 2017, 09:15

Hi folks,
I have a photograph in Lightroom, which I Exported at 300dpi with the long edge being 29cm (29cm being the length of the tri-fold leaflet that will be printed). This results in a 6MB jpg, which I want to put into a Quark document and Export as a PDF. Problem: doing this bumps up the size to a whopping 48MBs, which is too big for the printer company.
Obvious solution, go into the Options/Compression section of Quark's Export dialogue box and choose the downsample to 300dpi option. Unfortunately, this results in a 1.5 MB file with the company now saying the resolution is too low.
What I would like to know is how does a 6MB file placed into a 750KB Quark document, result in a 48MB PDF when exported without compression? Is this an issue with Quark or Adobe Acrobat?

Best,
Ray
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Re: Compression and Quark 8.5

Postby MikeWenzloff » 22 Mar 2017, 14:08

Hi Ray,

Something seems a tad off in the kb/mb sizes mentioned in conjunction with the export DPI.

That said, a 6mb JPG can, depending upon the compression LR is using, be actually many, many more MBs. See what happens if you export to TIFF without compression. What is the image size then? But even so, MBs and CMs have little to do with the number of pixels needed to express 300 dpi.

What are the image's pixel dimensions? 29 cm needs an image width of about 3450 px to resolve to 300 dpi for 29 cm.

But without seeing the file, I'm pretty much shooting in the dark.

Mike
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Re: Compression and Quark 8.5

Postby Ray200 » 23 Mar 2017, 04:40

Hi Mike,
Thanks for the reply. I have two files (both jpgs) to go into the Quark file. As you wrote, both files need to be c."3450" pixels to be 29cm and 300dpi; both are close to it as one is 3307 (3.4MBs) and the other is 3508 (4.49MBs).
When both jpgs are open in Photoshop they are, though, according to the Pixel Dimensions in the Image Size box, 24.2 MBs and 26.4MBs. This would partly explain why my two jpgs (combined size only c.8MBs) suddenly grow into a near 50MB file when I Export as PDF from Quark without compression. The Quark file is tiny too, only c. 6MBs. I know I'm missing something very basic re image resolution but I can't see what it is.

Best,
Ray
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Re: Compression and Quark 8.5

Postby MikeWenzloff » 23 Mar 2017, 08:35

Hi Ray, the Q file will only be representative of the preview images, not the images themselves. So that's why it is going to be so much smaller than the output PDF. I don't think you are missing anything.

If you need a smaller PDF, experiment with the compression options. But any downsampling in Q to 300 dpi shouldn't affect the PDF as much as you mention.

If possible, could you ZIP up the contents of the Q file and the images and upload the ZIP to dropbox or the like? If you can share this publicly, just put the download link into a forum response. If you cannot share publicly, you can feel free to send me a private message with the download link and once this is resolved it will be removed from my system.

Thanks, Mike
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Re: Compression and Quark 8.5

Postby Ray200 » 23 Mar 2017, 15:01

Hi Mike,
I messed around with the compression, as you mentioned, and I seem to get the best results from choosing the PDF/X-ia: 2001 option (with the Marks deselected). The file exported okay at 300dpi with a PDF size of 11MBs, markedly smaller than the near 50MBs I had without compression.
I suppose my confusion is more to do with how a 4MB jpg inserted into Quark transforms into a 24MB file when exported as a PDF. Am I mixing up a preview size with the actual size?
This forum has helped a lot as this question was related to my other one (and it's the same Quark file) where updating to 8.5 cured a minor font bug in my version 8. Playing about with the compression, as you suggested, did the trick. I just wish I understood the why and didn't waste so much time.

Best,
Ray
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Re: Compression and Quark 8.5

Postby MikeWenzloff » 24 Mar 2017, 14:29

Hi Ray, the why is just because a compressed JPG on disk is so much smaller than the compression in a PDF.

Basically an application has to decompress the image just to display it, which is why Photoshop shows the decompressed size at all. And the downsampling and compression options in a PDF are designed to preserve the image's integrity for the output intent in the PDF, not for disk storage as the original JPG is.

Mike
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Re: Compression and Quark 8.5

Postby UtahLlama » 28 Mar 2017, 16:52

A4 300dpi uncompressed cmyk TIF would be about 35-40MB.
RGB TIF would be about 3/4 this size.
The amount of detail in the image and the amount/quality of jpeg compression will affect the file size more than the resolution. But anywhere between 1 and 10MB could be normal.

If you are exporting jpeg direct from Lightroom then it would be best if Quark was able to push this straight into the pdf without decompressing and re-compressing, because re-jpegging a jpeg can be quite destructive to quality, I really thought this was possible so I'm not sure why you are getting such big variance in file size?

For best quality I'd recommend you export from Lightroom as a TIF, place that in Quark and Export to PDF, you can convert to Jpeg in Quark with Max quality or if you want a bit more reduction in File Size the in Acrobat Pro Use Save As Optimised pdf and jpeg there. Try to keep resampling (either resizing, rotating ) and re pegging down to a minimum.
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