Conversion of PDF files to ZIP

wmfs · 11-22-2016, 01:34 PM

When you select to convert PDF files to ZIP in Calibre, the file created when un-zipped will create a new directory contain a number of PNG files. However what is interesting is the if the original PDF files contained 'watermarks' these will be removed in the PNG files and a separate PNG created containing only the watermark.

Does anyone anyone how this is achieved?

Bill Seabrook

BetterRed · 11-22-2016, 03:16 PM

@wmfs - I know Imagemagick has that as an optional feature, there are lots of IM based gui and online wrappers out there that can do it. In version 2.57 Kovid replaced IM, IIRC with a Qt equivalent (QtImage/Paint ??), so I guess it can do it too.

BR

wmfs · 11-22-2016, 06:58 PM

Looks like you might be right @BetterRed! Using ImageMagick convert with -separate works in much the same way as Calibre, for example

convert -density 400 "myfile.pdf" -separate -resize 25% "myfile.png"

creates several .PNG files if a watermark is found.

Thanks

11-22-2016, 01:34 PM	#1
wmfs Member Posts: 13 Karma: 10 Join Date: Jun 2012 Device: snoy	Conversion of PDF files to ZIP When you select to convert PDF files to ZIP in Calibre, the file created when un-zipped will create a new directory contain a number of PNG files. However what is interesting is the if the original PDF files contained 'watermarks' these will be removed in the PNG files and a separate PNG created containing only the watermark. Does anyone anyone how this is achieved? Bill Seabrook Last edited by wmfs; 11-22-2016 at 01:54 PM. Reason: added Calibre

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11-22-2016, 03:16 PM	#2
BetterRed null operator (he/him) Posts: 20,544 Karma: 26954694 Join Date: Mar 2012 Location: Sydney Australia Device: none	@wmfs - I know Imagemagick has that as an optional feature, there are lots of IM based gui and online wrappers out there that can do it. In version 2.57 Kovid replaced IM, IIRC with a Qt equivalent (QtImage/Paint ??), so I guess it can do it too. BR

11-22-2016, 06:58 PM	#3
wmfs Member Posts: 13 Karma: 10 Join Date: Jun 2012 Device: snoy	Looks like you might be right @BetterRed! Using ImageMagick convert with -separate works in much the same way as Calibre, for example convert -density 400 "myfile.pdf" -separate* -resize 25% "myfile.png"* creates several .PNG files if a watermark is found. Thanks

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