I am using
gdal_translate to convert non-spatial PDFs to non-spatial TIFFs (intended for subsequent manual georeferencing).
This is my
gdal_translate -of GTiff -sds -co NBITS=1 --config GDAL_PDF_DPI 300 %input_pdf% %output_tif%
Here is what it looks like at ~8x magnification (note the "nibbling" around the edges of text and the complete loss of many "speckles"):
Input (rendered by Adobe Reader, disregard the slight blurring of edges):
Output (rendered by ArcMap):
If I do not specify the output bit depth (by omitting the
NBITS option), I can tell that GDAL is re-rasterizing and resampling the input 1-bit image into a blurred grayscale image:
Ideally it would just copy each pixel in the input straight to the output.
How can I retain the original resolution without information loss in the output? Should I use something else, like ImageMagick, Poppler or GhostScript?
All this re-rasterization GDAL is doing is painfully slow, I might add, so I think I will try one of the alternatives for that reason alone.