I am converting a pdf to .tiff file using ImageMagick and calling it from python using subprocess,run() but, I want the output file size to be limited to a maximum value say 40MB. -define extent max_value is not working for tiff like it works for jpeg images.
This is my code:
subprocess.run('magick convert -density 150 example.pdf -trim -thumbnail 500 result%04d.tif')
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I was trying to resize a pdf file to 8.5x11 with ImageMagick and in doing so, I am loosing the quality of my pdf file.
I was using convert source.pdf -extent 612x792 destination.pdf command.
Can someone please help me with this one?
Imagemagick is rasterizing the PDF, then scaling it, then producing an output PDF of differing dimensions, which contains raster data only.
Scale a PDF to fit directly like this:
cpdf -scale-to-fit "612 792" in.pdf -o out.pdf
This keeps the PDF's original vector artwork and fonts intact.
Imagemagick uses Ghostscript and will rasterize your PDF. It will not maintain its vectors. If you want higher quality, use a higher -density to rasterize and then resize back to whatever you want. For example, I use a density 4x the default of 72 or 288 and then resize by 25%=1/4 to get back to the nominal size.
convert -density 288 -units pixelsperinch image.pdf -resize 25% result.pdf
You can then include your -density 72 -gravity XX -extent 612x792 before the output.
Or you can compute do -density 288 etc and then just resize to 612x792.
I've tried this and it worked.
convert -density 300 -define pdf:fit-page=Letter -gravity Center source.pdf output.pdf
I am trying to combine multiple JPEG file into one single long file using this command
magick convert ..\galerry\*.jpg -gravity center -append longview.jpg
However while combining the files, imagemagick reached the limit of 65500 pixels
Is there any file format that can store image larger than 65500 pixels with the same compression as JPEG file format?
I'm trying to find the right command for compressing png and jpg files good enough for Google Page speed.
I'm using the following from my OSX termial:
convert -strip -quality 85 imagesource.png imagesource_optimized.png
The result is no difference in file size between the original and "optimized version. Am Is there a different command I can use?
Compression is fundamentally different between PNG and JPEG because PNG is lossless and JPEG is lossy.
With a JPEG the -quality parameter specifies how much quality should be retained.
With a PNG file, the -quality parameter specifies the strategy and the amount of time/effort zlib can spend to optimise your image - think gzip --best versus gzip --fast.
See https://www.imagemagick.org/script/command-line-options.php#quality
For PNG, I suggest pngcrush which you can install with homebrew using:
brew install pngcrush
For JPEG, either use -quality or specify a maximum size:
# Specify by quality
convert input.jpg -strip -quality 75% output.jpg
# Specify maximum size
convert input.jpg -strip -define jpeg:extent=300k output.jpg
Compression is fundamentally different between PNG and JPEG because PNG is lossless and JPEG is lossy.
Using ImageMagick's convert utility to convert some scanned jpg files to pbm files.
However, even if the option -quality 100 is used, the pbm's resolution still looks worse than the original scanned jpg file.
Worse, the scanned jpg file is a colored one, while the converted pbm is black and white.
Info of original jpg:
image size: 2256 × 1568 pixels
dpi: 300 pixels/inch
color model: RGB
info of the converted pbm:
image size: 2256 × 1568 pixels
dpi: 72 pixels/inch
color model: Gray
Currently, here is what I did to convert the format:
qiang#bonjour:~/scan$ convert scan000.jpg scan000.pbm
Am I missing any option to use with convert? As I mentioned earlier, -quality 100 had been tried, but to no avail.
Using ImageMagick, I think you want to output to PPM not PBM. Try
convert image.jpg image.ppm
or try the ascii version by using
convert image.jpg -compress none image.ppm
PBM is binary (black/white) and PGM is grayscale. If you want to keep color, then you need to use PPM.
Unfortunately, I believe that ImageMagick can only read DJVU format images. So you cannot write to it directly from ImageMagick.
I have been using the batch method to convert any number of PDFs to any other format in any DPI (Best way to convert pdf files to tiff files).
ImageMagick was updated (I run ImageMagick-7.0.3-Q16), and I though the old command:
convert -density 300 -compress LZW testfile.pdf testfile.jpg
could just be changed to:
magick -density 300 -compress LZW testfile.pdf testfile.jpg
Both the 'density' and the 'compress' functionality appear in the new manual... It does create a jpg, however, the DPI is 96 (default?) and it seems that the actual dimensions of the figure increases a lot.
(The actual text in the .bat file is
for %%f in (%*) DO "C:\Program Files\ImageMagick-7.0.3-Q16\magick.exe" -density 300 -compress LZW %%f %%f.jpg
but the issue also appears when I run the simplified code above...