I frequently export scanned PDFs to black and white using the quartz filter, in order to reduce file size. This has worked fine for years, but now in Big Sur they're appearing red, with blue text. What's up with that?? Can I fix it? (And why does Image Capture now have to create such huge files even when I only choose 300 dpi and scan in, supposedly, black and white?) I need to email these scans to people who need to print them, and it's impossible.
Boot into Safe Mode according to Start up your Mac in safe mode - Apple Support and see if the problem persists. Reboot normally and check again.
NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
The size of the scanned files depends not just on dpi but also on how the files are saved - ege a TIFF file will typically be much larger than a jpeg version of the same image.
Did you try the reduce file soze filter instead of the black and white filter?
If the problem does not show in Safe Mode then run Etrecheck and post its full report here.
I recently did a BW filter of a PDF from within ColorSync without a problem (Big Sur). You could try checking the filter to see if something changed. Also did the Reduce Size.
In Profiles go to Computer>Black & White. My profile is Version 2.2 dated July1, 2003.
Also, click through in Filters to see if something was added. Mine just states using the BW filter.
Thank you. I am aware of the effects of choice of file type. I always scan to PDF because it's the most universal format, well understood by anybody who can do so much as email, and what I'm going for is useful, printable information that my musicians can read. (I am an orchestra librarian.) Formerly scanned-to-PDF files (like, maybe five or so years ago, I forget what OS that was) of ten to twenty pages were a LOT smaller than what is now the norm, using Image Capture.
Yes, I have tried the file size reduction filter, on both text-type files (black ink or pencil on white paper) and more complex files that involve photographs. It only results in creating a highly pixelated file that is truly ugly and certainly not acceptable for placing on music stands.
I haven't messed with Safe Mode yet. Also, I didn't actually expect anyone to respond to my question (my questions on this board normally go unaddressed), so I took the one file I found to be corrupted, opened in Preview, and re-exported using the Quartz filter "black and white." Now it looks... black and white.
All of the reported "red" files have looked fine to me, on my machines, but other users have reported the files have arrived as red, when attached to emails. It was only today that I found out that my correspondents weren't just whining when they told me the files I sent were red, or orange, when I was sorting through PDFs to be set aside, and saw a red one.
I have seen one other user complain about this phenomenon, on the MacOSRumors site, so it's not just me and my machine.
Could it be anything to do with DropBox? Because, while I'm not quite sure - I'd have to document when this crops up in the future, and where I saved the file - I think maybe every time I've attached a "red" PDF to an email, it has come out of my DropBox folder. Yet, if I send the *link* to that same file to correspondents, so they can download it themselves, it seems to work.
HMMM.
I think ColorSync (and I haven't messed with it in decades) is oriented toward what one sees on one's own screen, and not to what appears when one emails a file. My problem is that users that I email files to, while those files appear to be just fine on my iMac (OS 11.2.3), appear on the other end to be red backgrounds with blue text.
I thought they were all just whiners, but now I think the issue is something else, because today I saw a red file on my iMac. Oof. So I'm trying to troubleshoot.
Nothing weird in Filters.
Would it be possible to share an example file showing the problem? Preferably the two versions, ie, the one without the filter and the one with it, that shows those strange colors.
You might send them to yourself using wetransfer and just post the link here.
I just printed out two pages of Edvard Grieg's Sonata Opus 7 E minor piano solo PDF to my monochrome laser printer. Then using an ancient Canon N650U flatbed scanner driven by VueScan Professional v9.7.5.2 on macOS 11.2.3, I scanned the printed pages in 1-bit (b/w) to a new PDF document.
Using Ghostscript v9.53.3, I used its ink_cov device to measure the CMYK page coverage in the scanned PDF, and the CMY columns were zero. The percentage of black on pages 1 and 2 of the PDF ranged from 9.8 to 11.8. Absolutely no RGB chroma crept into this PDF.
It may be possible that post-processing the Image Capture generated PDF with Preview, or the ColorSync tool allows chroma into the PDF. I cannot use Image Capture on this old Canon scanner for a comparison test.
PDFs converted to black and white appear red
