Scanned PDF xrefs blurred/pixelated
The firm I work for uses scans of county approved mylar plans for redline revisions. These looked fine prior to switching to BricsCAD, but are now incredibly pixelated to the point of being unreadable. They plot fine, but in the state they're in can't be worked on. Screenshot attached for reference.
What can be done for this, being as they aren't simply converted from CAD file to PDF?
Comments
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Try changing the background (BKGCOLOR) color to white.
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This also applies to scanned PDFs for those who are interrested
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I agree with Roy, if the background is black then switching to a white background usually solves the pixelation issue for inserted PDF's and (scanned) images. Ideally it should not make a difference for full colour images so this is something that could be put on the BricsCAD improvement wish list.
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Part of the problem seems to be how the PDF cache looks if BKGCOLOR is 256. Switching PDFCACHE off is worth a try although it may slow things down when dealing with big scanned PDFs.
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Is there any workaround aside from this? Having a white background is incredibly hard on my eyes. PDFCACHE might be an option, and I'll try it. The problem there would be big scans - some of the plans I deal with are 30x42 size, and I usually scan them at 300dpi to avoid any quality issues.
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Try inverting the colors of the scans in an image editing program.
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I've traced the issue to a setting in the Properties window: the "Adjust colors for background" dropdown. When this dropdown is set to yes, the pixelation occurs. When set to no, the PDF shows up as sharp and crisp as the original drawing does on paper. Does anyone know if there's a system variable that can be set to default this to "No"?
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@Mike said:
I've traced the issue to a setting in the Properties window: the "Adjust colors for background" dropdown. When this dropdown is set to yes, the pixelation occurs. When set to no, the PDF shows up as sharp and crisp as the original drawing does on paper. Does anyone know if there's a system variable that can be set to default this to "No"?As far as I'm aware there is no system variable for this, it is a property of the PDF object. Using this setting will mean you may no longer see parts of the pdf (as they are near to or match your background colour), and it will impact on how your drawing prints out. Have you tried raising a support request to ask for PDF display to be improved on dark backgrounds?
To explain how PDF's work in BricsCAD. To improved performance, recent versions of BricsCAD cache the attached PDF an image, with the image being displayed instead of the PDF. This is why PDF's can appear pixelated on the screen at some zoom levels. This caching process is for display only, when generating output (PRINT, PUBLISH) the original PDF is used. Switching the PDFCACHE off in SETTINGS can have significant performance impact with larger PDF documents. Instead of turning off you could try PDFCACHE = 1. This switches to real time generation when you zoom in.
With V19 you now have the option of using PDFIMPORT to import the PDF into the drawing. If you explore this option, then I recommend that you check the options available to you in SETTINGS.
Regards,
Jason Bourhill
BricsCAD V19 Ultimate
Quickly create HELP links on your forum posts0 -
PDF's are made up of fonts, vector graphics and raster images. Postscript fonts and vector graphics are readily and accurately converted to DXF or DWG format by BricsCAD and AutoCAD.. Any scan of a document would be a raster image, which will be pixelated to varying degrees, depending on the resolution. You need a special application to convert the raster image to lines. Basically it's the same process as OCR, and rarely works cleanly..
Until recently BricsCAD only had the capability to underlay a PDF (PDFATTACH), so you could draw lines over it. Now BricsCAD has a PDFIMPORT, which attempts to convert the fonts and vector graphics into compatible fonts, lines, and solid fills. It still doesn't do anything with raster images. They will appear as raster images of varying degree of pixelation, depending on the resolution of the image stored inside the PDF.
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Yes inverting the colors would make it easy and an accurate response to do so Pasco Connect
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Interesting thing is that I worked with vectorization software for drawings ( mainly maps which worked OK) some 30 years ago. Its tricky.
Have tested som new software out of interest. BUT for get it ! Nothing has happened in all these years.
Tracing or redrawing scanned technical drawings is the only real option depending on the accuracy you need.0 -
@Patrik Sparrman said:
Interesting thing is that I worked with vectorization software for drawings ( mainly maps which worked OK) some 30 years ago. Its tricky.
Have tested som new software out of interest. BUT for get it ! Nothing has happened in all these years.
Tracing or redrawing scanned technical drawings is the only real option depending on the accuracy you need.I agree with you Patrik. I haven't found any really good software for vectorization. I use a freebie on occasion. it is called. WinTopo. I see they have updated it. Perhaps it is better now.
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The benefit of a white background is that you can choose colors based on what colors show up best on white paper. When you choose a black screen, then the colors are wrong. E.g. yellow is highly visib9on scree, but invisible when printed in color.
Historically, white also became a good choice, because the reflected glare on the CRT is not noticable. You can probably tell that I am an advocate for always
If the white screen is a problem for you, you might try just adjusting the brightness and contrast of the monitor. I think that there are utilities in Nvivia's drivers to adjust video settings, bases in what app is being used at the time. So you can have special settings that are only used in the CAD program.
Another possible approach is set your background to be a very light gray. But in my experiments, that creates issues with colors like yellow.
Yet another approach is to work in model space most of the time, but then switch to one of the layouts, when the visibility of the PDF raster image is a problem.
-Joe0 -
Joe Dunfee,
Ah, the forever disputed topic, white or black background. My boss is a firm believer as you, that white is the best background color. I am a traditionalist, black is mobetta. I have used exclusively yellow text for the last 25 yrs. because yellow shows up so nicely on black, & it is generally the smallest objects (each letter) on the screen, & zoomed out any yellow is text. Looking @ a pc monitor for 10 hrs. a day, I find the black background much easier on my eyes. To deal w/ the issue you brought forth of printing the colors chosen on screen, I use a *.ctb file that changes all yellow to print black, @ a lineweight of .0039” so I can read the text on a “D” size dwg printed on “A” size paper, & read all the text. As mentioned, my boss insisted white is best for background, so when I close a dwg, I customarily run a lisp routine that purges & sets the text layer to white, just so my boss can view the text on his white background, & then he has a smile on his face, & life is good.
Regards, Mike0 -
The problem with CTB files, is that they almost never get transmitted to the recipient when the DWG file is transferred, and even company archives are often going to omit them at some point down the line.
It is not unusual for me to get drawings created as you normally do, and of course, a CTB file is not sent, or perhaps they just use a monochrome print style.
One company, in particular, has made it particularly difficult, by setting entity colors to things other than "by layer". Even worse, these are often buried inside blocks. Since these are many-layered architectural drawings, we often need to see many layers at once, and colors are necessary to distinguish what we are looking at. So, we always print in color. As a result, it is not unusual for me to need to spend a several hours (billed to the customer) to clean up his drawings and change the colors into something we can use and print. If he needs to send us a revision, the "clean up" process starts all over again from scratch.
I wonder if there is some sort of utility out there to automatically fix this kind of issue, even for drawings created by the "in particular" company above?
-Joe
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Joe,
W/ the CTB file ALWAYS printing ALL yellow as black, it is actually quite handy; so if we get a dwg using yellow, it always prints black. One of our CAD Standards is text is on layer TEXT, color BYLAYER, & one way to check the vendor or contractor dwgs is to set layer TEXT to color 6 (magenta), it then is really easy to tell if they have violated our CAD Standards. If so, we send them back & they get to correct it. After messing up a project or 2, they get the hint that our CAD Standards are not suggestions. As you mentioned, the color BYLAYER is also our worst found infraction, (we can thank some Autodesk CAD geek for telling us how wonderful color BYBLOCK is back in the 90s which prompted us all try it, & then realize “not only no, but ^%$# no). The lisp routine that I mentioned above to check color BYLAYER is used w/in a batch print program (Hurricane). Just flipping through the “A” size prints, the magenta text stands out, & we can just check a few & decide to send the lot back to the vendor/contractor for a redo, @ their expense because they failed to meet our CAD Standards.
Mike0 -
@Roy Klein Gebbinck said:
Try changing the background (BKGCOLOR) color to white.You can get the same effect by putting a solid white hatch behind your PDF, without changing BKGCOLOR. However, I like Mike's solution the best (set Adjust Colors for Background to No), although I'm still getting a few artefacts.
I am skeptical of the claims made by Jason Bourhill that: "Using this setting will mean you may no longer see parts of the pdf (as they are near to or match your background colour), and it will impact on how your drawing prints out."
I'm using V18. Perhaps since this thread has been quiet for a year, newer versions fixed the issue.
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