pdfqgis-3
Every time a PDF is opened using QGIS the resolution is quite poor. I believe this is because the standard gdal pdf driver behind QGIS uses a default value of 150 dpi. (see here https://gdal.org/drivers/raster/pdf.html)
But, when using gdal (e.g. gdal_translate) from the cmd window I am able to configure the desired dpi using the option -co GDAL_PDF_DPI 600.
Is it possible to change this option in QGIS?
Using Settings – Data source- GDAL – PDF only the create options can be changed.
One of the issue is with the transparency of raster
https://support.esri.com/en/bugs/nimbus/QlVHLTAwMDA5NTc2NQ==
Other issue is that ArcGIS Pro while exporting map to pdf do not have option to rasterize(ArcGIS Pro will get this in 2.3 version)
https://community.esri.com/ideas/14201-generalize-vector-data-on-export-settings
The solution of this problem is instead of sharing it as a pdf, Use the Print option print to file and while printing, Select Microsoft print to pdf. This results in rasterized map in pdf and it appears fine.
Update Now you have the option in version 2.3
This resolves the issue
I think the pdf you exported are already as you expect, but you are looking at the wrong metrics.
Let me explain: contrary to raster (Tiff) files, PDF files deriving from/including vectors do not have an inherent pixel-resolution. How many pixels you get out of the pdf depends on the settings of the rasterizer you use (GIMP, Photoshop, and any screen-viewer like Acrobat Reader).
From the file you shared I exported a pdf, and queried it with Imagemagick's identify, using first the default rasterizing resolution (72 pixels, shown implicitly and explicitly) and a highr resolution. you can see that at 300 dpi you would get the same pixel size you expect.
This is the same process as importing it in GIMP/Photoshop:
Importing @72dpi:
Importing the same file @300dpi:
Importing the same file @900 dpi:
Please keep in mind that these setting do not magically enhance your pdf, they just make a raster out of it with the desired pixel density, but the actual pixel resolution will still be determined by the exporting option.
In the examples above, you can see that the 900dpi file has more pixels, but not more information.
So, for example, using a setting of 3000 dpi will create an image which is 35080x24790 px, but will not yield a better definition than the one @300 dpi, if that is how you exported it.
$ identify karto.pdf
karto.pdf PDF 828x612 828x612+0+0 16-bit sRGB 3691B 0.000u 0:00.000
$ identify -density 72 karto.pdf
karto.pdf PDF 842x595 842x595+0+0 16-bit sRGB 813315B 0.030u 0:00.030
$ identify -density 300 karto.pdf
karto.pdf PDF 3508x2479 3508x2479+0+0 16-bit sRGB 7.6346MiB 0.240u 0:00.247
Best Answer
You should be able to set
GDAL_PDF_DPIas an environment variable.Go to
Settings / Options / Systemand add this environment variable with the desired value of 600 underEnvironment. Restart QGIS and see if it now works. This should also add it to the environment, so when you open the command window and rungdal_translateyou should not need to add it to the command line.For other variables you can set in this fashion for GDAL, see https://gdal.org/user/configoptions.html