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How to remove hidden lines that display in Acrobat but not in Chrome, etc.?

New Here ,
Jul 21, 2021 Jul 21, 2021

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I've been creating some PDFs by printing from the old (1996-era) Envoy viewer to PDF. In many of the graphic images on the resulting pages, there are hidden lines (I'm not sure of the exact terminology) that do not display in the original Envoy viewer, and do NOT display when I open the PDF in Chrome or Firefox or macOS Preview, but which are visible when I open the PDF in Acrobat. Here is a sample (attached). The lines seem to be there because they were parts of triangles that were supposed to have two sides hidden and only one side visible.

 

Is there any way to process the PDF to remove those extra lines? I've tried various export options, without success. I realize that there may simply be no solution to this, but I hope that one of the experts here might possibly have an answer.

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Edit and convert PDFs , Print and prepress

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Community Expert ,
Jul 21, 2021 Jul 21, 2021

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I can see the thin lines in Acrobat & Illustrator, unfortunately, they are composed of very thin filled shapes (not lines or strokes) therefore they are not easy to remove. Selecting by same fill in Illustrator results in selecting other wanted elements. Also, the fonts are not embedded and there are odd color changes when the file is opened in Illustrator. Is there an option to export to PDF from Envoy Viewer? What is the original file type?

Have you tried opening the original file in Acrobat?

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New Here ,
Jul 21, 2021 Jul 21, 2021

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Many thanks for those further details. The original file type was .EVY - an Envoy file. Tumbleweed's (later Novell's) Envoy was a rival product to Acrobat and did not have PDF export - it was designed an alternative to PDF, to be viewed only in the Envoy viewer or in a runtime executable that had the Viewer built in. The Envoy file was created in 1994, so probably in Windows 3.11 or in something like Ventura Publisher (though I don't know whether Ventura could be output to Envoy). Tumbleweed never made a full EVY-file editor available to the public, so there's no way to edit the original file.

 

What you say means that there's almost certainly no way to fix this, but I'm grateful to you for trying. One thing I do wonder about is why the shapes don't appear in non-Acrobat viewers: do the other viewers simply ignore lines that are as thin as these?

 

Again, thank you for confirming and clarifying!

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New Here ,
Jul 21, 2021 Jul 21, 2021

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And PS: the only software that opens EVY files is the Envoy viewer. Acrobat doesn't recognize it.

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Community Expert ,
Jul 22, 2021 Jul 22, 2021

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I have two suggestions, the easy way would be to take a screen shot of the original file open in Envoy viewer, then open the screen shot in Acrobat and save it as a PDF. If you need maximun quality, and have the time, here is the hard way;

1. Open the PDF in Acrobat and use a preflight profile to embed the fonts (Tools> Print Production> Preflight> Fixups> Embed fonts).

2. Use another preflight to separate the text, vector & images into layers (Preflight> Fixups> Layers> Create different layers for vector, text, image).

3. Turn off the layer visibility of the image and text layers by clicking the eyeball icon in the Acrobat layers panel and open the PDF in Photoshop, save it as a tiff (I used 300 dpi in my example, you can go higher if needed) retouch or erase the unwanted thin lines and save.

4. Open the layered PDF and from the layers fly-out menu, select Import as layer, navigate to the retouched tiff and create a new layer, save.

5. Create an InDesign page and place the layered PDF, Then place it a second time. Select the top PDF and go to Object> Layer options, turn off the original vector layer, set the transparency to multiply.

6. Set the object layer options of the bottom PDF to show the retouched layer only, save, export to a new PDF.

create layers.png

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New Here ,
Jul 22, 2021 Jul 22, 2021

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These are excellent suggestions. Thank you - and thank you for your expertise and trouble.

 

The difficulty in this case is that the original document is 710 pages long, and has diagrams with those extra lines on maybe 400 of those pages, so the manual labor isn't practical.

 

I'm content to live with this, though I would be interested to know why the lines don't display in Chrome, macOS Preview, etc., no matter how much I zoom in. If it's possible to figure out why this happens, maybe it would be possible to ask Adobe to provide an option to work in a similar way.

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Community Expert ,
Jul 23, 2021 Jul 23, 2021

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I know Apple Preview is not a great PDF viewer, it often does not correctly show layers, transparency, overprinting, interactivity, and other issues, which makes it unsuitable for accurate PDF viewing. You can make a feature request to Adobe to add a preflight to remove very small slivers of unwanted shapes (there is an existing a tool to remove actual thin lines). 

https://www.adobe.com/products/wishform.html

I suggest you run the preflight to embed the fonts on all pages, this may prevent other problems when your PDF is printed. With the PDF open in Acrobat, go to File> Properties> Fonts, all fonts should say embedded or subset.

If you will be using a commercial printer, discuss this issue with them, as they may have addtional tools to remove the lines.

embed preflight.png

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New Here ,
Jul 23, 2021 Jul 23, 2021

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This is extremely helpful - thank you again. I'll post that request on the wishform.

 

Meanwhile, one quick question: for future use, where is the tool that removes actual thin lines? I've searched for it, but haven't found it, and obviously I'm not looking in the right place.

 

Another question: I have a few PDFs created from this Envoy file; one was created in Windows 3.1 and has Type 1 fonts, but I can't find an option to embed those fonts. Is Type 1-embedding not possible under recent Acrobat versions? (I've read that Adobe is taking steps to get away from Type 1, but I don't know the details.)

 

Again, a thousand thanks!

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New Here ,
Jul 23, 2021 Jul 23, 2021

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And I just saw that Nitro PDF also does NOT display those thin lines. Unfortunately, if I print from Nitro PDF to the Nitro PDF driver, and display the output in Acrobat, the thin lines still appear.

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Community Expert ,
Jul 23, 2021 Jul 23, 2021

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Tools> Print Production> Fix Hairlines.

This tool is designed to increase the size of thin lines, but also works to change the line width (stroke) to zero.

After testing this, it does work, but a line with 0 pt stroke still appears in Acrobat. In Illustrator you could either select & delete it or change the color to (none), however Illustrator is not a universal PDF editor.

Is the embed fonts preflight profile not embedding Type 1 fonts? I don't know if this a new issue.

Hairline.png

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New Here ,
Jul 29, 2021 Jul 29, 2021

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A friend found that he could remove the thin lines by working with the Pitstop plugin. That costs more than I can afford to pay, but it seems to be the solution if anyone else encounters this problem. Thanks again for all these suggestions!

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Community Expert ,
Jul 29, 2021 Jul 29, 2021

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I'm wondering if it's the driver you are using to print to PDF. How are you doing this?

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New Here ,
Jul 29, 2021 Jul 29, 2021

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I've tried Adobe, a half-dozen GhostScript-based drivers, some CUPS-based drivers, CutePDF, NitroPDF, and a few others; a friend tried some OS/2 drivers. The results are always the same.

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