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Question

Large Image Size

Laserfiche Snapshot
Updated May 28, 2019
asked on April 18, 2019

I know there are a lot of questions/concerns with the size of image pages; however, I'm hoping to get any best practice feedback.

We want to be able to generate text for scanned pdfs, which requires generating pages. This means increasing the size of the document by 30x if in colour or 7x if in monochrome. We can update the dpi through the attributes - does anyone have an ideal number?

Further, I've played around with compression upon export of image pages to pdf, but I'm finding nothing working. For example, my settings are the following:

but a 21MB monochrome image file is still exported as a 21MB pdf file.

Any help appreciated.

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Replies

replied on April 18, 2019 • Show version history

Hi Robyn,

I don't have a formal recommendation for you, but can tell you the guide rails I used when coming up with some of this.  The default settings for our higher volume scanners results in some significantly large PDFs.  On the order of a few MB per page.  Recently, I've made some adjustments to the default settings and tuned the DPI down from 300 to 200 which resulted in a significant reduction in file/pagesize and not in noticeable quality.  Given you mention that your OCR'ing these, I would recommend some testing to see how the OCR engine does as you make adjustments.

I believe you are not seeing adjustments in the output file because you have the lossless option selected.  Try unselecting it and Download/export some PDFs as you refine the quality percent and see how that does with regards to output file size.  

Hopefully that helps get you some info to run with.

Will

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View 3 previous replies
replied on April 18, 2019

Hi Will,

thank you for your response. I've changed our generate pages to 200 dpi in the attributes, so I'm hoping that will help.

I tried selecting the lossless option, but still ending up with the same file size (21MB). Am I missing a different setting perhaps?

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replied on April 18, 2019 • Show version history

Hi Robyn,

Are these TIF images?  For kicks, try adjusting the 40 to 10 and to 90 then perform a download.  I would also be curious to see how the output changes (if at all) with the second checkbox to optimize compression for text on color images.

Another test would be to try the same from a different LF Client to rule out this PC's LF Client install.

Lastly, I'd recommend trying with a different doc.  For example, upload test PDF and choose to generate pages, look at the base filesize under the Page Info in Doc Properties then hit your tests with that doc.

Thanks,

Will

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replied on April 18, 2019

Hi Will,

Yes, these are TIFF files. I tried adjusting the %, with no changes. Whether that second checkbox (optimize compression for text on color images) is selected, makes no difference either.

Trying a different document: same results. No changes on size given the different settings.

No difference for other users on separate computers.

Very strange. Is this a VAR ticket?

 

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replied on April 18, 2019

Hi Robyn,

That certainly covers my battery of logical tests.  At a minimum you have some good data points to reference in your ticket if someone else doesn't chime in here.

I'll be curious to hear the end result.

Thanks,

Will

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replied on April 18, 2019

Will let you know!

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replied on April 19, 2019

Hi Robyn,

The conversion from PDF to TIFF inevitably causes a large increase in image size, and the subsequent conversion from TIFF back to PDF does result in a larger PDF than the original.

The strange thing is that the PDF should almost always be smaller than the source TIFF pages. 21MB sounds pretty large for a monochrome file.

Note that unless you explicitly tell Laserfiche to convert the PDF as monochrome (TIFF Group 4), the resulting pages will be color TIFF files (TIFF-LZW) even if the underlying image was monochrome.

Monochrome pages are significantly smaller than color so it is possible that you're not actually generating true "monochrome" files at all. We scan a lot of documents in monochrome and the PDFs are only in the KB range.

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replied on May 28, 2019

Have you tried setting the options for generating pages to use Snapshot? I've found this can generate a smaller tiff. However, you'll need to make sure the resulting image quality is good enough.

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