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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?

Blurred PDF.png
1909 x 1053 - 707K

Comments

  • Try changing the background (BKGCOLOR) color to white.

  • This also applies to scanned PDFs for those who are interrested

  • 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.

  • edited July 29

    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.

  • 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.

  • Try inverting the colors of the scans in an image editing program.

  • @Roy Klein Gebbinck said:
    Try inverting the colors of the scans in an image editing program.

    There are any number of reason why I can't do it this way, all relating to my boss's OCD.

  • 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"?

  • @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 posts

    CAD Concepts

  • 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.

  • edited September 11

    Yes inverting the colors would make it easy and an accurate response to do so Pasco Connect

  • 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.

  • @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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